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• Problems with DNS propagation 10 days after a change was made

  - by runlevel6

  The engineering team I work with has been in the process of moving equipment from one datacenter to another. Ten days ago we moved one of our name servers authoritative for our client's domains (ns1.faithhiway.com) and updated its IP address with its respective DNS provider (register.com) to point to the new datacenter. All tests done show that this name server is correctly running at its new location and when queried, returning the correct response for any domains it is responsible for. The problem is that well after 72 hours had gone by we were still seeing more DNS activity at its old IP address than at the new. The good news is that we kept a name server responding on the old IP address for the time being so we are not seeing any issues with the domains our nameserver is responsible for but the goal is to retire that as soon as possible. As you can see from WhatsMyDNS.net, a decent amount of propagation has occurred over the last 10 days since we made this change, but still there are some locations reporting our original IP. Considering that the TTL is only 3600 with the name servers responsible for this domain, it does not make any sense to myself or the other engineers working with me that we are having this issue. Now if I run a DNS check using one of the Register.com DNS servers (direct nameservers for faithhiway.com), I get the following (correct) result: # dig @dns01.gpn.register.com ns1.faithhiway.com A ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_5.3 <<>> @dns01.gpn.register.com. ns1.faithhiway.com A ; (1 server found) ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43232 ;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 5 ;; QUESTION SECTION: ;ns1.faithhiway.com. IN A ;; ANSWER SECTION: ns1.faithhiway.com. 3601 IN A 206.127.2.71 ;; AUTHORITY SECTION: faithhiway.com. 3600 IN NS dns01.gpn.register.com. faithhiway.com. 3600 IN NS dns02.gpn.register.com. faithhiway.com. 3600 IN NS dns03.gpn.register.com. faithhiway.com. 3600 IN NS dns04.gpn.register.com. faithhiway.com. 3600 IN NS dns05.gpn.register.com. ;; ADDITIONAL SECTION: dns01.gpn.register.com. 3600 IN A 98.124.192.1 dns02.gpn.register.com. 3600 IN A 98.124.197.1 dns03.gpn.register.com. 3600 IN A 98.124.193.1 dns04.gpn.register.com. 3600 IN A 69.64.145.225 dns05.gpn.register.com. 3600 IN A 98.124.196.1 ;; Query time: 50 msec ;; SERVER: 98.124.192.1#53(98.124.192.1) ;; WHEN: Thu Jan 27 15:16:57 2011 ;; MSG SIZE rcvd: 269 Just as a reference, here are the results when the same query is checked against a variety of Public DNS servers: Google: # dig @8.8.8.8 ns1.faithhiway.com A ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_5.3 <<>> @8.8.8.8. ns1.faithhiway.com A ; (1 server found) ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12773 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;ns1.faithhiway.com. IN A ;; ANSWER SECTION: ns1.faithhiway.com. 997 IN A 206.127.2.71 ;; Query time: 29 msec ;; SERVER: 8.8.8.8#53(8.8.8.8) ;; WHEN: Thu Jan 27 15:17:31 2011 ;; MSG SIZE rcvd: 52 Level 3: # dig @4.2.2.1 ns1.faithhiway.com A ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_5.3 <<>> @4.2.2.1. ns1.faithhiway.com A ; (1 server found) ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 46505 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;ns1.faithhiway.com. IN A ;; ANSWER SECTION: ns1.faithhiway.com. 2623 IN A 206.127.2.71 ;; Query time: 7 msec ;; SERVER: 4.2.2.1#53(4.2.2.1) ;; WHEN: Thu Jan 27 15:18:35 2011 ;; MSG SIZE rcvd: 52 Verizon: # dig @151.197.0.38 ns1.faithhiway.com A ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_5.3 <<>> @151.197.0.38. ns1.faithhiway.com A ; (1 server found) ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32658 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;ns1.faithhiway.com. IN A ;; ANSWER SECTION: ns1.faithhiway.com. 3601 IN A 206.127.2.71 ;; Query time: 81 msec ;; SERVER: 151.197.0.38#53(151.197.0.38) ;; WHEN: Thu Jan 27 15:19:15 2011 ;; MSG SIZE rcvd: 52 Cisco: # dig @64.102.255.44 ns1.faithhiway.com A ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_5.3 <<>> @64.102.255.44. ns1.faithhiway.com A ; (1 server found) ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 39689 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 0 ;; QUESTION SECTION: ;ns1.faithhiway.com. IN A ;; ANSWER SECTION: ns1.faithhiway.com. 3601 IN A 206.127.2.71 ;; AUTHORITY SECTION: faithhiway.com. 3600 IN NS dns01.gpn.register.com. faithhiway.com. 3600 IN NS dns04.gpn.register.com. faithhiway.com. 3600 IN NS dns05.gpn.register.com. faithhiway.com. 3600 IN NS dns02.gpn.register.com. faithhiway.com. 3600 IN NS dns03.gpn.register.com. ;; Query time: 105 msec ;; SERVER: 64.102.255.44#53(64.102.255.44) ;; WHEN: Thu Jan 27 15:20:05 2011 ;; MSG SIZE rcvd: 165 OpenDNS: # dig @208.67.222.222 ns1.faithhiway.com A ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_5.3 <<>> @208.67.222.222. ns1.faithhiway.com A ; (1 server found) ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12328 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;ns1.faithhiway.com. IN A ;; ANSWER SECTION: ns1.faithhiway.com. 169507 IN A 207.200.19.162 ;; Query time: 6 msec ;; SERVER: 208.67.222.222#53(208.67.222.222) ;; WHEN: Thu Jan 27 15:19:29 2011 ;; MSG SIZE rcvd: 52 SpeakEasy: # dig @66.93.87.2 ns1.faithhiway.com A ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-4.P1.el5_5.3 <<>> @66.93.87.2. ns1.faithhiway.com A ; (1 server found) ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9342 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;ns1.faithhiway.com. IN A ;; ANSWER SECTION: ns1.faithhiway.com. 169323 IN A 207.200.19.162 ;; Query time: 69 msec ;; SERVER: 66.93.87.2#53(66.93.87.2) ;; WHEN: Thu Jan 27 15:19:51 2011 ;; MSG SIZE rcvd: 52 As you can see above, the majority of queries are returning the correct result. But a few (OpenDNS and SpeakEasy in the examples above) are still showing the old IP address. Considering the length of time that has gone by, it seems obvious to me that either we have made a mistake and not thoroughly handled the DNS changes on our end (likely) or there is a problem with either the DNS provider for this domain (Register) or with some of the DNS servers out in the wild (rather unlikely). Any advice on how I can proceed with this? UPDATE (January 31, 2011): First of all, I apologize for the length of both the original question and this update. I contemplated removing some of the excess from the original post but just in case this problem and its solution are helpful to someone else in the future I'm just going to leave everything as it is. Anyway, I've been doing some more research into this problem, and have discovered the following interesting occurrence. While running a check on the glue records for faithhiway.com always resolve correctly, if I go and check a client domain (where ns1.faithhiway.com is authoritative), I get a strange response. It looks like the root servers are returning nsX.faithhiway.com as their old IP addresses still (under Additional Section). Because we have a server still there responding to DNS queries, the trace finishes and returns the correct IP addresses as the final step (again, under Additional Section). The example below uses one of the domains that we use that uses ns1.faithhiway.com as its authoritative DNS server. # dig +trace +nosearch +all +norecurse ignitemail.com ; <<>> DiG 9.2.4 <<>> +trace +nosearch +all +norecurse ignitemail.com ;; global options: printcmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 46856 ;; flags: qr ra; QUERY: 1, ANSWER: 13, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;. IN NS ;; ANSWER SECTION: . 7986 IN NS a.root-servers.net. . 7986 IN NS b.root-servers.net. . 7986 IN NS c.root-servers.net. . 7986 IN NS d.root-servers.net. . 7986 IN NS e.root-servers.net. . 7986 IN NS f.root-servers.net. . 7986 IN NS g.root-servers.net. . 7986 IN NS h.root-servers.net. . 7986 IN NS i.root-servers.net. . 7986 IN NS j.root-servers.net. . 7986 IN NS k.root-servers.net. . 7986 IN NS l.root-servers.net. . 7986 IN NS m.root-servers.net. ;; Query time: 39 msec ;; SERVER: 8.8.8.8#53(8.8.8.8) ;; WHEN: Mon Jan 31 09:22:17 2011 ;; MSG SIZE rcvd: 228 ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16325 ;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 13, ADDITIONAL: 14 ;; QUESTION SECTION: ;ignitemail.com. IN A ;; AUTHORITY SECTION: com. 172800 IN NS h.gtld-servers.net. com. 172800 IN NS m.gtld-servers.net. com. 172800 IN NS i.gtld-servers.net. com. 172800 IN NS l.gtld-servers.net. com. 172800 IN NS c.gtld-servers.net. com. 172800 IN NS k.gtld-servers.net. com. 172800 IN NS d.gtld-servers.net. com. 172800 IN NS f.gtld-servers.net. com. 172800 IN NS b.gtld-servers.net. com. 172800 IN NS a.gtld-servers.net. com. 172800 IN NS e.gtld-servers.net. com. 172800 IN NS g.gtld-servers.net. com. 172800 IN NS j.gtld-servers.net. ;; ADDITIONAL SECTION: a.gtld-servers.net. 172800 IN A 192.5.6.30 a.gtld-servers.net. 172800 IN AAAA 2001:503:a83e::2:30 b.gtld-servers.net. 172800 IN A 192.33.14.30 b.gtld-servers.net. 172800 IN AAAA 2001:503:231d::2:30 c.gtld-servers.net. 172800 IN A 192.26.92.30 d.gtld-servers.net. 172800 IN A 192.31.80.30 e.gtld-servers.net. 172800 IN A 192.12.94.30 f.gtld-servers.net. 172800 IN A 192.35.51.30 g.gtld-servers.net. 172800 IN A 192.42.93.30 h.gtld-servers.net. 172800 IN A 192.54.112.30 i.gtld-servers.net. 172800 IN A 192.43.172.30 j.gtld-servers.net. 172800 IN A 192.48.79.30 k.gtld-servers.net. 172800 IN A 192.52.178.30 l.gtld-servers.net. 172800 IN A 192.41.162.30 ;; Query time: 64 msec ;; SERVER: 198.41.0.4#53(a.root-servers.net) ;; WHEN: Mon Jan 31 09:22:17 2011 ;; MSG SIZE rcvd: 504 ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12860 ;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 2, ADDITIONAL: 2 ;; QUESTION SECTION: ;ignitemail.com. IN A ;; AUTHORITY SECTION: ignitemail.com. 172800 IN NS ns1.faithhiway.com. ignitemail.com. 172800 IN NS ns2.faithhiway.com. ;; ADDITIONAL SECTION: ns1.faithhiway.com. 172800 IN A 207.200.19.162 ns2.faithhiway.com. 172800 IN A 207.200.50.142 ;; Query time: 152 msec ;; SERVER: 192.54.112.30#53(h.gtld-servers.net) ;; WHEN: Mon Jan 31 09:22:17 2011 ;; MSG SIZE rcvd: 111 ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43016 ;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2 ;; QUESTION SECTION: ;ignitemail.com. IN A ;; ANSWER SECTION: ignitemail.com. 3600 IN A 206.127.2.64 ;; AUTHORITY SECTION: ignitemail.com. 3600 IN NS ns1.faithhiway.com. ignitemail.com. 3600 IN NS ns2.faithhiway.com. ;; ADDITIONAL SECTION: ns1.faithhiway.com. 3600 IN A 206.127.2.71 ns2.faithhiway.com. 3600 IN A 206.127.2.72 ;; Query time: 25 msec ;; SERVER: 206.127.2.71#53(ns1.faithhiway.com) ;; WHEN: Mon Jan 31 09:22:18 2011 ;; MSG SIZE rcvd: 127 I really think this is a problem we have somewhere in our setup, but whether it is ignorance of something with DNS on my or my fellow engineer's end or just a dumb mistake we made, I have yet to find it.

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• ASP.NET MVC 3 Hosting :: How to Deploy Web Apps Using ASP.NET MVC 3, Razor and EF Code First - Part I

  - by mbridge

  First, you can download the source code from http://efmvc.codeplex.com. The following frameworks will be used for this step by step tutorial. public class Category {     public int CategoryId { get; set; }     [Required(ErrorMessage = "Name Required")]     [StringLength(25, ErrorMessage = "Must be less than 25 characters")]     public string Name { get; set;}     public string Description { get; set; }     public virtual ICollection<Expense> Expenses { get; set; } } Expense Class public class Expense {             public int ExpenseId { get; set; }            public string  Transaction { get; set; }     public DateTime Date { get; set; }     public double Amount { get; set; }     public int CategoryId { get; set; }     public virtual Category Category { get; set; } }    Define Domain Model Let’s create domain model for our simple web application Category Class We have two domain entities - Category and Expense. A single category contains a list of expense transactions and every expense transaction should have a Category. In this post, we will be focusing on CRUD operations for the entity Category and will be working on the Expense entity with a View Model object in the later post. And the source code for this application will be refactored over time. The above entities are very simple POCO (Plain Old CLR Object) classes and the entity Category is decorated with validation attributes in the System.ComponentModel.DataAnnotations namespace. Now we want to use these entities for defining model objects for the Entity Framework 4. Using the Code First approach of Entity Framework, we can first define the entities by simply writing POCO classes without any coupling with any API or database library. This approach lets you focus on domain model which will enable Domain-Driven Development for applications. EF code first support is currently enabled with a separate API that is runs on top of the Entity Framework 4. EF Code First is reached CTP 5 when I am writing this article. Creating Context Class for Entity Framework We have created our domain model and let’s create a class in order to working with Entity Framework Code First. For this, you have to download EF Code First CTP 5 and add reference to the assembly EntitFramework.dll. You can also use NuGet to download add reference to EEF Code First. public class MyFinanceContext : DbContext {     public MyFinanceContext() : base("MyFinance") { }     public DbSet<Category> Categories { get; set; }     public DbSet<Expense> Expenses { get; set; }         }   The above class MyFinanceContext is derived from DbContext that can connect your model classes to a database. The MyFinanceContext class is mapping our Category and Expense class into database tables Categories and Expenses using DbSet<TEntity> where TEntity is any POCO class. When we are running the application at first time, it will automatically create the database. EF code-first look for a connection string in web.config or app.config that has the same name as the dbcontext class. If it is not find any connection string with the convention, it will automatically create database in local SQL Express database by default and the name of the database will be same name as the dbcontext class. You can also define the name of database in constructor of the the dbcontext class. Unlike NHibernate, we don’t have to use any XML based mapping files or Fluent interface for mapping between our model and database. The model classes of Code First are working on the basis of conventions and we can also use a fluent API to refine our model. The convention for primary key is ‘Id’ or ‘<class name>Id’.  If primary key properties are detected with type ‘int’, ‘long’ or ‘short’, they will automatically registered as identity columns in the database by default. Primary key detection is not case sensitive. We can define our model classes with validation attributes in the System.ComponentModel.DataAnnotations namespace and it automatically enforces validation rules when a model object is updated or saved. Generic Repository for EF Code First We have created model classes and dbcontext class. Now we have to create generic repository pattern for data persistence with EF code first. If you don’t know about the repository pattern, checkout Martin Fowler’s article on Repository Let’s create a generic repository to working with DbContext and DbSet generics. public interface IRepository<T> where T : class     {         void Add(T entity);         void Delete(T entity);         T GetById(long Id);         IEnumerable<T> All();     } RepositoryBasse – Generic Repository class protected MyFinanceContext Database {     get { return database ?? (database = DatabaseFactory.Get()); } } public virtual void Add(T entity) {     dbset.Add(entity);            }        public virtual void Delete(T entity) {     dbset.Remove(entity); }   public virtual T GetById(long id) {     return dbset.Find(id); }   public virtual IEnumerable<T> All() {     return dbset.ToList(); } } DatabaseFactory class public class DatabaseFactory : Disposable, IDatabaseFactory {     private MyFinanceContext database;     public MyFinanceContext Get()     {         return database ?? (database = new MyFinanceContext());     }     protected override void DisposeCore()     {         if (database != null)             database.Dispose();     } } Unit of Work If you are new to Unit of Work pattern, checkout Fowler’s article on Unit of Work . According to Martin Fowler, the Unit of Work pattern "maintains a list of objects affected by a business transaction and coordinates the writing out of changes and the resolution of concurrency problems." Let’s create a class for handling Unit of Work public interface IUnitOfWork {     void Commit(); } UniOfWork class public class UnitOfWork : IUnitOfWork {     private readonly IDatabaseFactory databaseFactory;     private MyFinanceContext dataContext;       public UnitOfWork(IDatabaseFactory databaseFactory)     {         this.databaseFactory = databaseFactory;     }       protected MyFinanceContext DataContext     {         get { return dataContext ?? (dataContext = databaseFactory.Get()); }     }       public void Commit()     {         DataContext.Commit();     } } The Commit method of the UnitOfWork will call the commit method of MyFinanceContext class and it will execute the SaveChanges method of DbContext class.   Repository class for Category In this post, we will be focusing on the persistence against Category entity and will working on other entities in later post. Let’s create a repository for handling CRUD operations for Category using derive from a generic Repository RepositoryBase<T>. public class CategoryRepository: RepositoryBase<Category>, ICategoryRepository     {     public CategoryRepository(IDatabaseFactory databaseFactory)         : base(databaseFactory)         {         }                } public interface ICategoryRepository : IRepository<Category> { } If we need additional methods than generic repository for the Category, we can define in the CategoryRepository. Dependency Injection using Unity 2.0 If you are new to Inversion of Control/ Dependency Injection or Unity, please have a look on my articles at http://weblogs.asp.net/shijuvarghese/archive/tags/IoC/default.aspx. I want to create a custom lifetime manager for Unity to store container in the current HttpContext. public class HttpContextLifetimeManager<T> : LifetimeManager, IDisposable {     public override object GetValue()     {         return HttpContext.Current.Items[typeof(T).AssemblyQualifiedName];     }     public override void RemoveValue()     {         HttpContext.Current.Items.Remove(typeof(T).AssemblyQualifiedName);     }     public override void SetValue(object newValue)     {         HttpContext.Current.Items[typeof(T).AssemblyQualifiedName] = newValue;     }     public void Dispose()     {         RemoveValue();     } } Let’s create controller factory for Unity in the ASP.NET MVC 3 application.                 404, String.Format(                     "The controller for path '{0}' could not be found" +     "or it does not implement IController.",                 reqContext.HttpContext.Request.Path));       if (!typeof(IController).IsAssignableFrom(controllerType))         throw new ArgumentException(                 string.Format(                     "Type requested is not a controller: {0}",                     controllerType.Name),                     "controllerType");     try     {         controller= container.Resolve(controllerType) as IController;     }     catch (Exception ex)     {         throw new InvalidOperationException(String.Format(                                 "Error resolving controller {0}",                                 controllerType.Name), ex);     }     return controller; }   } Configure contract and concrete types in Unity Let’s configure our contract and concrete types in Unity for resolving our dependencies. private void ConfigureUnity() {     //Create UnityContainer               IUnityContainer container = new UnityContainer()                 .RegisterType<IDatabaseFactory, DatabaseFactory>(new HttpContextLifetimeManager<IDatabaseFactory>())     .RegisterType<IUnitOfWork, UnitOfWork>(new HttpContextLifetimeManager<IUnitOfWork>())     .RegisterType<ICategoryRepository, CategoryRepository>(new HttpContextLifetimeManager<ICategoryRepository>());                 //Set container for Controller Factory                ControllerBuilder.Current.SetControllerFactory(             new UnityControllerFactory(container)); } In the above ConfigureUnity method, we are registering our types onto Unity container with custom lifetime manager HttpContextLifetimeManager. Let’s call ConfigureUnity method in the Global.asax.cs for set controller factory for Unity and configuring the types with Unity. protected void Application_Start() {     AreaRegistration.RegisterAllAreas();     RegisterGlobalFilters(GlobalFilters.Filters);     RegisterRoutes(RouteTable.Routes);     ConfigureUnity(); } Developing web application using ASP.NET MVC 3 We have created our domain model for our web application and also have created repositories and configured dependencies with Unity container. Now we have to create controller classes and views for doing CRUD operations against the Category entity. Let’s create controller class for Category Category Controller public class CategoryController : Controller {     private readonly ICategoryRepository categoryRepository;     private readonly IUnitOfWork unitOfWork;           public CategoryController(ICategoryRepository categoryRepository, IUnitOfWork unitOfWork)     {         this.categoryRepository = categoryRepository;         this.unitOfWork = unitOfWork;     }       public ActionResult Index()     {         var categories = categoryRepository.All();         return View(categories);     }     [HttpGet]     public ActionResult Edit(int id)     {         var category = categoryRepository.GetById(id);         return View(category);     }       [HttpPost]     public ActionResult Edit(int id, FormCollection collection)     {         var category = categoryRepository.GetById(id);         if (TryUpdateModel(category))         {             unitOfWork.Commit();             return RedirectToAction("Index");         }         else return View(category);                 }       [HttpGet]     public ActionResult Create()     {         var category = new Category();         return View(category);     }           [HttpPost]     public ActionResult Create(Category category)     {         if (!ModelState.IsValid)         {             return View("Create", category);         }                     categoryRepository.Add(category);         unitOfWork.Commit();         return RedirectToAction("Index");     }       [HttpPost]     public ActionResult Delete(int  id)     {         var category = categoryRepository.GetById(id);         categoryRepository.Delete(category);         unitOfWork.Commit();         var categories = categoryRepository.All();         return PartialView("CategoryList", categories);       }        } Creating Views in Razor Now we are going to create views in Razor for our ASP.NET MVC 3 application.  Let’s create a partial view CategoryList.cshtml for listing category information and providing link for Edit and Delete operations. CategoryList.cshtml @using MyFinance.Helpers; @using MyFinance.Domain; @model IEnumerable<Category>      <table>         <tr>         <th>Actions</th>         <th>Name</th>          <th>Description</th>         </tr>     @foreach (var item in Model) {             <tr>             <td>                 @Html.ActionLink("Edit", "Edit",new { id = item.CategoryId })                 @Ajax.ActionLink("Delete", "Delete", new { id = item.CategoryId }, new AjaxOptions { Confirm = "Delete Expense?", HttpMethod = "Post", UpdateTargetId = "divCategoryList" })                           </td>             <td>                 @item.Name             </td>             <td>                 @item.Description             </td>         </tr>         }       </table>     <p>         @Html.ActionLink("Create New", "Create")     </p> The delete link is providing Ajax functionality using the Ajax.ActionLink. This will call an Ajax request for Delete action method in the CategoryCotroller class. In the Delete action method, it will return Partial View CategoryList after deleting the record. We are using CategoryList view for the Ajax functionality and also for Index view using for displaying list of category information. Let’s create Index view using partial view CategoryList  Index.chtml @model IEnumerable<MyFinance.Domain.Category> @{     ViewBag.Title = "Index"; }    <h2>Category List</h2>    <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script>    <div id="divCategoryList">               @Html.Partial("CategoryList", Model) </div> We can call the partial views using Html.Partial helper method. Now we are going to create View pages for insert and update functionality for the Category. Both view pages are sharing common user interface for entering the category information. So I want to create an EditorTemplate for the Category information. We have to create the EditorTemplate with the same name of entity object so that we can refer it on view pages using @Html.EditorFor(model => model) . So let’s create template with name Category. Category.cshtml @model MyFinance.Domain.Category <div class="editor-label"> @Html.LabelFor(model => model.Name) </div> <div class="editor-field"> @Html.EditorFor(model => model.Name) @Html.ValidationMessageFor(model => model.Name) </div> <div class="editor-label"> @Html.LabelFor(model => model.Description) </div> <div class="editor-field"> @Html.EditorFor(model => model.Description) @Html.ValidationMessageFor(model => model.Description) </div> Let’s create view page for insert Category information @model MyFinance.Domain.Category   @{     ViewBag.Title = "Save"; }   <h2>Create</h2>   <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>   @using (Html.BeginForm()) {     @Html.ValidationSummary(true)     <fieldset>         <legend>Category</legend>                @Html.EditorFor(model => model)               <p>             <input type="submit" value="Create" />         </p>     </fieldset> }   <div>     @Html.ActionLink("Back to List", "Index") </div> ViewStart file In Razor views, we can add a file named _viewstart.cshtml in the views directory  and this will be shared among the all views with in the Views directory. The below code in the _viewstart.cshtml, sets the Layout page for every Views in the Views folder.     @{     Layout = "~/Views/Shared/_Layout.cshtml"; } Tomorrow, we will cotinue the second part of this article. :)

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• C#/.NET Little Wonders: The Useful But Overlooked Sets

  - by James Michael Hare

  Once again we consider some of the lesser known classes and keywords of C#.  Today we will be looking at two set implementations in the System.Collections.Generic namespace: HashSet<T> and SortedSet<T>.  Even though most people think of sets as mathematical constructs, they are actually very useful classes that can be used to help make your application more performant if used appropriately. A Background From Math In mathematical terms, a set is an unordered collection of unique items.  In other words, the set {2,3,5} is identical to the set {3,5,2}.  In addition, the set {2, 2, 4, 1} would be invalid because it would have a duplicate item (2).  In addition, you can perform set arithmetic on sets such as: Intersections: The intersection of two sets is the collection of elements common to both.  Example: The intersection of {1,2,5} and {2,4,9} is the set {2}. Unions: The union of two sets is the collection of unique items present in either or both set.  Example: The union of {1,2,5} and {2,4,9} is {1,2,4,5,9}. Differences: The difference of two sets is the removal of all items from the first set that are common between the sets.  Example: The difference of {1,2,5} and {2,4,9} is {1,5}. Supersets: One set is a superset of a second set if it contains all elements that are in the second set. Example: The set {1,2,5} is a superset of {1,5}. Subsets: One set is a subset of a second set if all the elements of that set are contained in the first set. Example: The set {1,5} is a subset of {1,2,5}. If We’re Not Doing Math, Why Do We Care? Now, you may be thinking: why bother with the set classes in C# if you have no need for mathematical set manipulation?  The answer is simple: they are extremely efficient ways to determine ownership in a collection. For example, let’s say you are designing an order system that tracks the price of a particular equity, and once it reaches a certain point will trigger an order.  Now, since there’s tens of thousands of equities on the markets, you don’t want to track market data for every ticker as that would be a waste of time and processing power for symbols you don’t have orders for.  Thus, we just want to subscribe to the stock symbol for an equity order only if it is a symbol we are not already subscribed to. Every time a new order comes in, we will check the list of subscriptions to see if the new order’s stock symbol is in that list.  If it is, great, we already have that market data feed!  If not, then and only then should we subscribe to the feed for that symbol. So far so good, we have a collection of symbols and we want to see if a symbol is present in that collection and if not, add it.  This really is the essence of set processing, but for the sake of comparison, let’s say you do a list instead: 1: // class that handles are order processing service 2: public sealed class OrderProcessor 3: { 4: // contains list of all symbols we are currently subscribed to 5: private readonly List<string> _subscriptions = new List<string>(); 6:  7: ... 8: } Now whenever you are adding a new order, it would look something like: 1: public PlaceOrderResponse PlaceOrder(Order newOrder) 2: { 3: // do some validation, of course... 4:  5: // check to see if already subscribed, if not add a subscription 6: if (!_subscriptions.Contains(newOrder.Symbol)) 7: { 8: // add the symbol to the list 9: _subscriptions.Add(newOrder.Symbol); 10: 11: // do whatever magic is needed to start a subscription for the symbol 12: } 13:  14: // place the order logic! 15: } What’s wrong with this?  In short: performance!  Finding an item inside a List<T> is a linear - O(n) – operation, which is not a very performant way to find if an item exists in a collection. (I used to teach algorithms and data structures in my spare time at a local university, and when you began talking about big-O notation you could immediately begin to see eyes glossing over as if it was pure, useless theory that would not apply in the real world, but I did and still do believe it is something worth understanding well to make the best choices in computer science). Let’s think about this: a linear operation means that as the number of items increases, the time that it takes to perform the operation tends to increase in a linear fashion.  Put crudely, this means if you double the collection size, you might expect the operation to take something like the order of twice as long.  Linear operations tend to be bad for performance because they mean that to perform some operation on a collection, you must potentially “visit” every item in the collection.  Consider finding an item in a List<T>: if you want to see if the list has an item, you must potentially check every item in the list before you find it or determine it’s not found. Now, we could of course sort our list and then perform a binary search on it, but sorting is typically a linear-logarithmic complexity – O(n * log n) - and could involve temporary storage.  So performing a sort after each add would probably add more time.  As an alternative, we could use a SortedList<TKey, TValue> which sorts the list on every Add(), but this has a similar level of complexity to move the items and also requires a key and value, and in our case the key is the value. This is why sets tend to be the best choice for this type of processing: they don’t rely on separate keys and values for ordering – so they save space – and they typically don’t care about ordering – so they tend to be extremely performant.  The .NET BCL (Base Class Library) has had the HashSet<T> since .NET 3.5, but at that time it did not implement the ISet<T> interface.  As of .NET 4.0, HashSet<T> implements ISet<T> and a new set, the SortedSet<T> was added that gives you a set with ordering. HashSet<T> – For Unordered Storage of Sets When used right, HashSet<T> is a beautiful collection, you can think of it as a simplified Dictionary<T,T>.  That is, a Dictionary where the TKey and TValue refer to the same object.  This is really an oversimplification, but logically it makes sense.  I’ve actually seen people code a Dictionary<T,T> where they store the same thing in the key and the value, and that’s just inefficient because of the extra storage to hold both the key and the value. As it’s name implies, the HashSet<T> uses a hashing algorithm to find the items in the set, which means it does take up some additional space, but it has lightning fast lookups!  Compare the times below between HashSet<T> and List<T>: Operation HashSet<T> List<T> Add() O(1) O(1) at end O(n) in middle Remove() O(1) O(n) Contains() O(1) O(n)   Now, these times are amortized and represent the typical case.  In the very worst case, the operations could be linear if they involve a resizing of the collection – but this is true for both the List and HashSet so that’s a less of an issue when comparing the two. The key thing to note is that in the general case, HashSet is constant time for adds, removes, and contains!  This means that no matter how large the collection is, it takes roughly the exact same amount of time to find an item or determine if it’s not in the collection.  Compare this to the List where almost any add or remove must rearrange potentially all the elements!  And to find an item in the list (if unsorted) you must search every item in the List. So as you can see, if you want to create an unordered collection and have very fast lookup and manipulation, the HashSet is a great collection. And since HashSet<T> implements ICollection<T> and IEnumerable<T>, it supports nearly all the same basic operations as the List<T> and can use the System.Linq extension methods as well. All we have to do to switch from a List<T> to a HashSet<T>  is change our declaration.  Since List and HashSet support many of the same members, chances are we won’t need to change much else. 1: public sealed class OrderProcessor 2: { 3: private readonly HashSet<string> _subscriptions = new HashSet<string>(); 4:  5: // ... 6:  7: public PlaceOrderResponse PlaceOrder(Order newOrder) 8: { 9: // do some validation, of course... 10: 11: // check to see if already subscribed, if not add a subscription 12: if (!_subscriptions.Contains(newOrder.Symbol)) 13: { 14: // add the symbol to the list 15: _subscriptions.Add(newOrder.Symbol); 16: 17: // do whatever magic is needed to start a subscription for the symbol 18: } 19: 20: // place the order logic! 21: } 22:  23: // ... 24: } 25: Notice, we didn’t change any code other than the declaration for _subscriptions to be a HashSet<T>.  Thus, we can pick up the performance improvements in this case with minimal code changes. SortedSet<T> – Ordered Storage of Sets Just like HashSet<T> is logically similar to Dictionary<T,T>, the SortedSet<T> is logically similar to the SortedDictionary<T,T>. The SortedSet can be used when you want to do set operations on a collection, but you want to maintain that collection in sorted order.  Now, this is not necessarily mathematically relevant, but if your collection needs do include order, this is the set to use. So the SortedSet seems to be implemented as a binary tree (possibly a red-black tree) internally.  Since binary trees are dynamic structures and non-contiguous (unlike List and SortedList) this means that inserts and deletes do not involve rearranging elements, or changing the linking of the nodes.  There is some overhead in keeping the nodes in order, but it is much smaller than a contiguous storage collection like a List<T>.  Let’s compare the three: Operation HashSet<T> SortedSet<T> List<T> Add() O(1) O(log n) O(1) at end O(n) in middle Remove() O(1) O(log n) O(n) Contains() O(1) O(log n) O(n)   The MSDN documentation seems to indicate that operations on SortedSet are O(1), but this seems to be inconsistent with its implementation and seems to be a documentation error.  There’s actually a separate MSDN document (here) on SortedSet that indicates that it is, in fact, logarithmic in complexity.  Let’s put it in layman’s terms: logarithmic means you can double the collection size and typically you only add a single extra “visit” to an item in the collection.  Take that in contrast to List<T>’s linear operation where if you double the size of the collection you double the “visits” to items in the collection.  This is very good performance!  It’s still not as performant as HashSet<T> where it always just visits one item (amortized), but for the addition of sorting this is a good thing. Consider the following table, now this is just illustrative data of the relative complexities, but it’s enough to get the point: Collection Size O(1) Visits O(log n) Visits O(n) Visits 1 1 1 1 10 1 4 10 100 1 7 100 1000 1 10 1000   Notice that the logarithmic – O(log n) – visit count goes up very slowly compare to the linear – O(n) – visit count.  This is because since the list is sorted, it can do one check in the middle of the list, determine which half of the collection the data is in, and discard the other half (binary search).  So, if you need your set to be sorted, you can use the SortedSet<T> just like the HashSet<T> and gain sorting for a small performance hit, but it’s still faster than a List<T>. Unique Set Operations Now, if you do want to perform more set-like operations, both implementations of ISet<T> support the following, which play back towards the mathematical set operations described before: IntersectWith() – Performs the set intersection of two sets.  Modifies the current set so that it only contains elements also in the second set. UnionWith() – Performs a set union of two sets.  Modifies the current set so it contains all elements present both in the current set and the second set. ExceptWith() – Performs a set difference of two sets.  Modifies the current set so that it removes all elements present in the second set. IsSupersetOf() – Checks if the current set is a superset of the second set. IsSubsetOf() – Checks if the current set is a subset of the second set. For more information on the set operations themselves, see the MSDN description of ISet<T> (here). What Sets Don’t Do Don’t get me wrong, sets are not silver bullets.  You don’t really want to use a set when you want separate key to value lookups, that’s what the IDictionary implementations are best for. Also sets don’t store temporal add-order.  That is, if you are adding items to the end of a list all the time, your list is ordered in terms of when items were added to it.  This is something the sets don’t do naturally (though you could use a SortedSet with an IComparer with a DateTime but that’s overkill) but List<T> can. Also, List<T> allows indexing which is a blazingly fast way to iterate through items in the collection.  Iterating over all the items in a List<T> is generally much, much faster than iterating over a set. Summary Sets are an excellent tool for maintaining a lookup table where the item is both the key and the value.  In addition, if you have need for the mathematical set operations, the C# sets support those as well.  The HashSet<T> is the set of choice if you want the fastest possible lookups but don’t care about order.  In contrast the SortedSet<T> will give you a sorted collection at a slight reduction in performance.   Technorati Tags: C#,.Net,Little Wonders,BlackRabbitCoder,ISet,HashSet,SortedSet

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• Entity Framework 4.3.1 Code based Migrations and Connector/Net 6.6

  - by GABMARTINEZ

   Code-based migrations is a new feature as part of the Connector/Net support for Entity Framework 4.3.1. In this tutorial we'll see how we can use it so we can keep track of the changes done to our database creating a new application using the code first approach. If you don't have a clear idea about how code first works we highly recommend you to check this subject before going further with this tutorial. Creating our Model and Database with Code First  From VS 2010  1. Create a new console application 2.  Add the latest Entity Framework official package using Package Manager Console (Tools Menu, then Library Package Manager -> Package Manager Console). In the Package Manager Console we have to type  Install-Package EntityFramework This will add the latest version of this library.  We will also need to make some changes to your config file. A <configSections> was added which contains the version you have from EntityFramework.  An <entityFramework> section was also added where you can set up some initialization. This section is optional and by default is generated to use SQL Express. Since we don't need it for now (we'll see more about it below) let's leave this section empty as shown below. 3. Create a new Model with a simple entity. 4. Enable Migrations to generate the our Configuration class. In the Package Manager Console we have to type  Enable-Migrations; This will make some changes in our application. It will create a new folder called Migrations where all the migrations representing the changes we do to our model.  It will also create a Configuration class that we'll be using to initialize our SQL Generator and some other values like if we want to enable Automatic Migrations.  You can see that it already has the name of our DbContext. You can also create you Configuration class manually. 5. Specify our Model Provider. We need to specify in our Class Configuration that we'll be using MySQLClient since this is not part of the generated code. Also please make sure you have added the MySql.Data and the MySql.Data.Entity references to your project. using MySql.Data.Entity;   // Add the MySQL.Data.Entity namespace public Configuration() { this.AutomaticMigrationsEnabled = false; SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());    // This will add our MySQLClient as SQL Generator } 6. Add our Data Provider and set up our connection string <connectionStrings> <add name="PersonalContext" connectionString="server=localhost;User Id=root;database=Personal;" providerName="MySql.Data.MySqlClient" /> </connectionStrings> <system.data> <DbProviderFactories> <remove invariant="MySql.Data.MySqlClient" /> <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.6.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" /> </DbProviderFactories> </system.data> * The version recommended to use of Connector/Net is 6.6.2 or earlier. At this point we can create our database and then start working with Migrations. So let's do some data access so our database get's created. You can run your application and you'll get your database Personal as specified in our config file. Add our first migration Migrations are a great resource as we can have a record for all the changes done and will generate the MySQL statements required to apply these changes to the database. Let's add a new property to our Person class public string Email { get; set; } If you try to run your application it will throw an exception saying  The model backing the 'PersonelContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269). So as suggested let's add our first migration for this change. In the Package Manager Console let's type Add-Migration AddEmailColumn Now we have the corresponding class which generate the necessary operations to update our database. namespace MigrationsFromScratch.Migrations { using System.Data.Entity.Migrations; public partial class AddEmailColumn : DbMigration { public override void Up(){ AddColumn("People", "Email", c => c.String(unicode: false)); } public override void Down() { DropColumn("People", "Email"); } } } In the Package Manager Console let's type Update-Database Now you can check your database to see all changes were succesfully applied. Now let's add a second change and generate our second migration public class Person   {       [Key]       public int PersonId { get; set;}       public string Name { get; set; }       public string Address {get; set;}       public string Email { get; set; }       public List<Skill> Skills { get; set; }   }   public class Skill   {     [Key]     public int SkillId { get; set; }     public string Description { get; set; }   }   public class PersonelContext : DbContext   {     public DbSet<Person> Persons { get; set; }     public DbSet<Skill> Skills { get; set; }   } If you would like to customize any part of this code you can do that at this step. You can see there is the up method which can update your database and the down that can revert the changes done. If you customize any code you should make sure to customize in both methods. Now let's apply this change. Update-database -verbose I added the verbose flag so you can see all the SQL generated statements to be run. Downgrading changes So far we have always upgraded to the latest migration, but there may be times when you want downgrade to a specific migration. Let's say we want to return to the status we have before our last migration. We can use the -TargetMigration option to specify the migration we'd like to return. Also you can use the -verbose flag. If you like to go  back to the Initial state you can do: Update-Database -TargetMigration:$InitialDatabase  or equivalent: Update-Database -TargetMigration:0  Migrations doesn't allow by default a migration that would ocurr in a data loss. One case when you can got this message is for example in a DropColumn operation. You can override this configuration by setting AutomaticMigrationDataLossAllowed to true in the configuration class. Also you can set your Database Initializer in case you want that these Migrations can be applied automatically and you don't have to go all the way through creating a migration and updating later the changes. Let's see how. Database Initialization by Code We can specify an initialization strategy by using Database.SetInitializer (http://msdn.microsoft.com/en-us/library/gg679461(v=vs.103)). One of the strategies that I found very useful when you are at a development stage (I mean not for production) is the MigrateDatabaseToLatestVersion. This strategy will make all the necessary migrations each time there is a change in our model that needs a database replication, this also implies that we have to enable AutomaticMigrationsEnabled flag in our Configuration class. public Configuration()         {             AutomaticMigrationsEnabled = true;             AutomaticMigrationDataLossAllowed = true;             SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());    // This will add our MySQLClient as SQL Generator          } In the new EntityFramework section of your Config file we can set this at a context level basis.  The syntax is as follows: <contexts> <context type="Custom DbContext name, Assembly name"> <databaseInitializer type="System.Data.Entity.MigrateDatabaseToLatestVersion`2[[ Custom DbContext name, Assembly name],  [Configuration class name, Assembly name]],  EntityFramework" /> </context> </contexts> In our example this would be: The syntax is kind of odd but very convenient. This way all changes will always be applied when we do any data access in our application. There are a lot of new things to explore in EF 4.3.1 and Migrations so we'll continue writing some more posts about it. Please let us know if you have any questions or comments, also please check our forums here where we keep answering questions in general for the community.  Hope you found this information useful. Happy MySQL/.Net Coding! 

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• Dynamic Types and DynamicObject References in C#

  - by Rick Strahl

  I've been working a bit with C# custom dynamic types for several customers recently and I've seen some confusion in understanding how dynamic types are referenced. This discussion specifically centers around types that implement IDynamicMetaObjectProvider or subclass from DynamicObject as opposed to arbitrary type casts of standard .NET types. IDynamicMetaObjectProvider types  are treated special when they are cast to the dynamic type. Assume for a second that I've created my own implementation of a custom dynamic type called DynamicFoo which is about as simple of a dynamic class that I can think of:public class DynamicFoo : DynamicObject { Dictionary<string, object> properties = new Dictionary<string, object>(); public string Bar { get; set; } public DateTime Entered { get; set; } public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; if (!properties.ContainsKey(binder.Name)) return false; result = properties[binder.Name]; return true; } public override bool TrySetMember(SetMemberBinder binder, object value) { properties[binder.Name] = value; return true; } } This class has an internal dictionary member and I'm exposing this dictionary member through a dynamic by implementing DynamicObject. This implementation exposes the properties dictionary so the dictionary keys can be referenced like properties (foo.NewProperty = "Cool!"). I override TryGetMember() and TrySetMember() which are fired at runtime every time you access a 'property' on a dynamic instance of this DynamicFoo type. Strong Typing and Dynamic Casting I now can instantiate and use DynamicFoo in a couple of different ways: Strong TypingDynamicFoo fooExplicit = new DynamicFoo(); var fooVar = new DynamicFoo(); These two commands are essentially identical and use strong typing. The compiler generates identical code for both of them. The var statement is merely a compiler directive to infer the type of fooVar at compile time and so the type of fooExplicit is DynamicFoo, just like fooExplicit. This is very static - nothing dynamic about it - and it completely ignores the IDynamicMetaObjectProvider implementation of my class above as it's never used. Using either of these I can access the native properties:DynamicFoo fooExplicit = new DynamicFoo();// static typing assignmentsfooVar.Bar = "Barred!"; fooExplicit.Entered = DateTime.Now; // echo back static values Console.WriteLine(fooVar.Bar); Console.WriteLine(fooExplicit.Entered); but I have no access whatsoever to the properties dictionary. Basically this creates a strongly typed instance of the type with access only to the strongly typed interface. You get no dynamic behavior at all. The IDynamicMetaObjectProvider features don't kick in until you cast the type to dynamic. If I try to access a non-existing property on fooExplicit I get a compilation error that tells me that the property doesn't exist. Again, it's clearly and utterly non-dynamic. Dynamicdynamic fooDynamic = new DynamicFoo(); fooDynamic on the other hand is created as a dynamic type and it's a completely different beast. I can also create a dynamic by simply casting any type to dynamic like this:DynamicFoo fooExplicit = new DynamicFoo(); dynamic fooDynamic = fooExplicit; Note that dynamic typically doesn't require an explicit cast as the compiler automatically performs the cast so there's no need to use as dynamic. Dynamic functionality works at runtime and allows for the dynamic wrapper to look up and call members dynamically. A dynamic type will look for members to access or call in two places: Using the strongly typed members of the object Using theIDynamicMetaObjectProvider Interface methods to access members So rather than statically linking and calling a method or retrieving a property, the dynamic type looks up - at runtime  - where the value actually comes from. It's essentially late-binding which allows runtime determination what action to take when a member is accessed at runtime *if* the member you are accessing does not exist on the object. Class members are checked first before IDynamicMetaObjectProvider interface methods are kick in. All of the following works with the dynamic type:dynamic fooDynamic = new DynamicFoo(); // dynamic typing assignments fooDynamic.NewProperty = "Something new!"; fooDynamic.LastAccess = DateTime.Now; // dynamic assigning static properties fooDynamic.Bar = "dynamic barred"; fooDynamic.Entered = DateTime.Now; // echo back dynamic values Console.WriteLine(fooDynamic.NewProperty); Console.WriteLine(fooDynamic.LastAccess); Console.WriteLine(fooDynamic.Bar); Console.WriteLine(fooDynamic.Entered); The dynamic type can access the native class properties (Bar and Entered) and create and read new ones (NewProperty,LastAccess) all using a single type instance which is pretty cool. As you can see it's pretty easy to create an extensible type this way that can dynamically add members at runtime dynamically. The Alter Ego of IDynamicObject The key point here is that all three statements - explicit, var and dynamic - declare a new DynamicFoo(), but the dynamic declaration results in completely different behavior than the first two simply because the type has been cast to dynamic. Dynamic binding means that the type loses its typical strong typing, compile time features. You can see this easily in the Visual Studio code editor. As soon as you assign a value to a dynamic you lose Intellisense and you see which means there's no Intellisense and no compiler type checking on any members you apply to this instance. If you're new to the dynamic type it might seem really confusing that a single type can behave differently depending on how it is cast, but that's exactly what happens when you use a type that implements IDynamicMetaObjectProvider. Declare the type as its strong type name and you only get to access the native instance members of the type. Declare or cast it to dynamic and you get dynamic behavior which accesses native members plus it uses IDynamicMetaObjectProvider implementation to handle any missing member definitions by running custom code. You can easily cast objects back and forth between dynamic and the original type:dynamic fooDynamic = new DynamicFoo(); fooDynamic.NewProperty = "New Property Value"; DynamicFoo foo = fooDynamic; foo.Bar = "Barred"; Here the code starts out with a dynamic cast and a dynamic assignment. The code then casts back the value to the DynamicFoo. Notice that when casting from dynamic to DynamicFoo and back we typically do not have to specify the cast explicitly - the compiler can induce the type so I don't need to specify as dynamic or as DynamicFoo. Moral of the Story This easy interchange between dynamic and the underlying type is actually super useful, because it allows you to create extensible objects that can expose non-member data stores and expose them as an object interface. You can create an object that hosts a number of strongly typed properties and then cast the object to dynamic and add additional dynamic properties to the same type at runtime. You can easily switch back and forth between the strongly typed instance to access the well-known strongly typed properties and to dynamic for the dynamic properties added at runtime. Keep in mind that dynamic object access has quite a bit of overhead and is definitely slower than strongly typed binding, so if you're accessing the strongly typed parts of your objects you definitely want to use a strongly typed reference. Reserve dynamic for the dynamic members to optimize your code. The real beauty of dynamic is that with very little effort you can build expandable objects or objects that expose different data stores to an object interface. I'll have more on this in my next post when I create a customized and extensible Expando object based on DynamicObject.© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• ASP.NET MVC2 Access-Control: How to do authorization dynamically?

  - by Shaharyar

  We're currently rewriting our organizations ASP.NET MVC application which has been written twice already. (Once MVC1, once MVC2). (Thank god it wasn't production ready and too mature back then). This time, anyhow, it's going to be the real deal because we'll be implementing more and more features as time passes and the testruns with MVC1 and MVC2 showed that we're ready to upscale. Until now we were using Controller and Action authorization with AuthorizeAttribute's. But that won't do it any longer because our views are supposed to show different results based on the logged in user. Use Case: Let's say you're a major of a city and you login to a federal managed software and you can only access and edit the citizens in your city. Where you are allowed to access those citizens via an entry in a specialized MajorHasRightsForCity table containing a MajorId and a CityId. What I thought of is something like this: Public ViewResult Edit(int cityId) { if(Access.UserCanEditCity(currentUser, cityId) { var currentCity = Db.Cities.Single(c => c.id == cityId); Return View(currentCity); } else { TempData["ErrorMessage"] = "Yo are not awesome enough to edit that shizzle!" Return View(); } The static class Access would do all kinds of checks and return either true or false from it's methods. This implies that I would need to change and edit all of my controllers every time I change something. (Which would be a pain, because all unit tests would need to be adjusted every time something changes..) Is doing something like that even allowed?

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• asp.net mvc, IIS 6 vs IIS7.5, and integrated windows authentication causing javascript errors?

  - by chris

  This is a very strange one. I have an asp.net MVC 1 app. Under IIS6, with no anon access - only integrated windows auth - every thing works fine. I have the following on most of my Foo pages: <% using (Html.BeginForm()) { %> Show All: <%= Html.CheckBox("showAll", new { onClick = "$(this).parent('form:first').submit();" })%> <% } %> Clicking on the checkbox causes a post, the page is reloaded, everything is good. When I look at the access logs, that's what I see, with one oddity - the js library is requested during the page first request, but not for any subsequent page requests. Log looks like: GET / 401 GET / 200 GET /Content/Site.css 304 GET /Scripts/jquery-1.3.2.min.js 401 GET /Scripts/jquery-ui-1.7.2.custom.min.js 401 GET /Scripts/jquery.tablesorter.min.js 401 GET /Scripts/jquery-1.3.2.min.js 304 GET /Scripts/jquery-ui-1.7.2.custom.min.js 304 GET /Scripts/jquery.tablesorter.min.js 304 GET /Content/Images/logo.jpg 401 GET /Content/Images/logo.jpg 304 GET /Foo 401 GET /Foo 200 POST /Foo/Delete 302 GET /Foo/List 200 POST /Foo/List 200 This corresponds to home page, click on "Foo", delete a record, click a checkbox (which causes the 2nd POST). Under IIS7.5, it sometimes fails - the click on the check box doesn't cause a postback, but there are no obvious reasons why. I've noticed under IIS7.5 that every single page request re-issues the requests for the js libraries - the first one a 401, followed by either a 200 (OK) or 304 (not modified), as opposed to the above log extract where that only happened during the 1st request. Is there any way to eliminate the 401 requests? Could a timing issue have something to do with the click being ignored? Would increasing the number of concurrent connections help? Any other ideas? I'm at a bit of a loss to explain this.

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• publishing asp.net website give "Object reference not set to an instance of an object." error

  - by Johan

  Good day I am using VS 2008 I am getting fed up with this error. I have search all over the web and tried every possible suggestion to this error I could find. 1. delete app_code, build, add files back, publish. (did not work) 2. delete temporary asp.net files (did not work) in the end I even tried the command line and get the following stacktrace. error ASPRUNTIME: Object reference not set to an instance of an object. [NullReferenceException]: Object reference not set to an instance of an object. at System.Web.Compilation.BuildManager.CopyPrecompiledFile(VirtualFile vfile, String destPhysicalPath) at System.Web.Compilation.BuildManager.CopyStaticFilesRecursive(VirtualDirect ory sourceVdir, String destPhysicalDir, Boolean topLevel) at System.Web.Compilation.BuildManager.CopyStaticFilesRecursive(VirtualDirect ory sourceVdir, String destPhysicalDir, Boolean topLevel) at System.Web.Compilation.BuildManager.CopyStaticFilesRecursive(VirtualDirect ory sourceVdir, String destPhysicalDir, Boolean topLevel) at System.Web.Compilation.BuildManager.PrecompileAppInternal(VirtualPath star tingVirtualDir) at System.Web.Compilation.BuildManager.PrecompileApp(VirtualPath startingVirt ualDir) at System.Web.Compilation.BuildManager.PrecompileApp(ClientBuildManagerCallba ck callback) at System.Web.Compilation.BuildManagerHost.PrecompileApp(ClientBuildManagerCa llback callback) at System.Web.Compilation.BuildManagerHost.PrecompileApp(ClientBuildManagerCa llback callback) at System.Web.Compilation.ClientBuildManager.PrecompileApplication(ClientBuil dManagerCallback callback, Boolean forceCleanBuild) at System.Web.Compilation.ClientBuildManager.PrecompileApplication(ClientBuil dManagerCallback callback) at System.Web.Compilation.Precompiler.Main(String[] args) I used the following command line: aspnet_compiler.exe -p d:\code\websites\brokerweb -v / d:\code\websites\published -f -c -errorstack -u Please help as I cannot publish this site at all at present and it worked fine for quite a long time now before this stupid error. Regards Johan

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• ASP.Net How to enforce the HTTP get URL format?

  - by Hamish Grubijan

  [Sorry about a messy question. I believe I am targeting .Net 2.0 (for now)] Hi, I am an ASP.NET noob. For starters I am building a page that parses a URL string and populates a table in a database. I want that string to be strictly of the form: http://<server>:<port>/PageName.aspx?A=1&B=2&C=3&D=4&E=5 The order of the arguments do not matter, I just do not want any of them missing, or any extras. Here is what I tried (yes, it is ugly; I just want to get it to work first): #if (DEBUG) // Maps parameter names to their human readable names. // Used for error checking. private static Dictionary<string, string> paramNameToDisplayName = new Dictionary<string, string> { { A, "a"}, { B, "b"}, { C, "c"}, { D, "d"}, { E, "e"}, { F, "f"}, }; [Conditional("DEBUG")] private void validateRequestParameters(HttpRequest request) { bool endResponse = false; // Use foreach var foreach (string expectedParameterName in paramNameToDisplayName.Keys) { if (request[expectedParameterName] == null) { Response.Write(String.Format("No parameter \"{0}\", aka {1} was passed to the configuration generator. Check your URL string / cookie.", expectedParameterName, paramNameToDisplayName[expectedParameterName])); endResponse = true; } } // Use foreach var foreach (string actualParameterName in request.Params) { if (!paramNameToDisplayName.ContainsKey(actualParameterName)) { Response.Write(String.Format("The parameter \"{0}\", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.", actualParameterName)); endResponse = true; } } if (endResponse) { Response.End(); } } #endif and it works ok, except that it complains about all sorts of other stuff: http://localhost:1796/AddStatusUpdate.aspx?X=0 No parameter "A", aka a was passed to the configuration generator. Check your URL string / cookie.No parameter "B", aka b was passed to the configuration generator. Check your URL string / cookie.No parameter "C", aka c was passed to the configuration generator. Check your URL string / cookie.No parameter "D", aka d was passed to the configuration generator. Check your URL string / cookie.No parameter "E", aka e was passed to the configuration generator. Check your URL string / cookie.No parameter "F", aka f was passed to the configuration generator. Check your URL string / cookie.The parameter "X", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "ASP.NET_SessionId", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "ALL_HTTP", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "ALL_RAW", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "APPL_MD_PATH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "APPL_PHYSICAL_PATH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "AUTH_TYPE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "AUTH_USER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "AUTH_PASSWORD", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "LOGON_USER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_USER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_COOKIE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_FLAGS", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_ISSUER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_KEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SECRETKEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SERIALNUMBER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SERVER_ISSUER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SERVER_SUBJECT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SUBJECT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CONTENT_LENGTH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CONTENT_TYPE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "GATEWAY_INTERFACE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_KEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_SECRETKEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_SERVER_ISSUER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_SERVER_SUBJECT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "INSTANCE_ID", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "INSTANCE_META_PATH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "LOCAL_ADDR", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "PATH_INFO", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "PATH_TRANSLATED", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "QUERY_STRING", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_ADDR", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_HOST", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_PORT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REQUEST_METHOD", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SCRIPT_NAME", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_NAME", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_PORT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_PORT_SECURE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_PROTOCOL", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_SOFTWARE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "URL", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_CACHE_CONTROL", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_CONNECTION", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT_CHARSET", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT_ENCODING", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT_LANGUAGE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_COOKIE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_HOST", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_USER_AGENT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.Thread was being aborted. Is there some way for me to separate the implicit and the explicit parameters, or is it not doable? Should I even bother? Perhaps the philosophy of get is to just throw away that what is not needed. Thanks!

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• Capturing unhandled exceptions in .Net 2.0. Wrong event called.

  - by SoMoS

  Hello, I'm investigating a bit about how the unhandled exceptions are managed in .Net and I'm getting unexpected results that I would like to share with you to see what do you think about. The first one is pretty simple to see. I wrote this code to do the test, just a button that throws an Exception on the same thread that created the Form: Public Class Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Throw New Exception() End Sub Private Sub UnhandledException(ByVal sender As Object, ByVal e As UnhandledExceptionEventArgs) MsgBox(String.Format("Exception: {0}. Ending: {1}. AppDomain: {2}", CType(e.ExceptionObject, Exception).Message, e.IsTerminating.ToString(), AppDomain.CurrentDomain.FriendlyName)) End Sub Private Sub UnhandledThreadException(ByVal sender As Object, ByVal e As System.Threading.ThreadExceptionEventArgs) MsgBox(String.Format("Exception: {0}. AppDomain: {1}", e.Exception.Message(), AppDomain.CurrentDomain.FriendlyName)) End Sub Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load AddHandler AppDomain.CurrentDomain.UnhandledException, AddressOf UnhandledException AddHandler Application.ThreadException, AddressOf UnhandledThreadException End Sub End Class When I execute the code inside the Visual Studio the UnhandledException is called as expected but when I execute the application from Windows the UndhanledThreadException is called instead. ¿?¿?¿¿?¿? Someone has any idea of what can be happening here? Thanks in advance.

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• Complete list of tools and technologies that make up a solid ASP.NET MVC 2 development environment f

  - by Dr Dork

  This question is related to another wiki I found on SO, but I'd like to develop a more comprehensive example of an automated ASP MVC 2 development environment that can be used to develop and deploy a wide range of small-scale websites by beginners. As far as characteristics of the dev environment go, I'd like to focus on beginner-friendly over powerful since the other wiki focuses more on advanced, powerful setups. This information is targeted for beginners (that already know C# and understand web dev concepts) that have selected... ASP.NET MVC 2 as their dev framework Visual Studio 2010 Pro (or 2008 Pro SP1) as their IDE Windows 7 as their OS and are looking for a quick and easy-to-setup environment that covers managing, building, testing, tracking, and deploying their website with as much automation as possible. A system that can be used for becoming familiar with the whole process, as well as a launching point for exploring other, more custom and powerful systems. Since we've already selected the Compiler, Framework, and OS, I'd like to develop ideas for... Code editor (unless you feel VS will suffice for all areas of code) Database and related tools Unit testing (VS?) Continuous integration build system (VS?) Project Planning Issue tracking Deployment (VS?) Source management (VS?) ASP, C#, VS, and related blogs that beginners can follow Any other categories I'm probably missing Since we're already using Visual Studio, I'd like to focus on the out-of-the-box solutions and features built into Visual Studio, unless you feel there are better solutions that work well with VS and are easier to use than the features built directly into VS. Thanks so much in advance for your wisdom!

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• How to ajax load a parent-child listbox in JQuery/Asp.net MVC popup?

  - by melaos

  hi guys, i'm new to the asp.net mvc. and i have a link which will popup show a 3 panes listbox which allows the user to select country, region and language. and when the user click on the language, this will redirect back to the controller and refresh the page and show the proper localized content. i was thinking of using a jquery dialog/modal to do this but so i try using fancybox for this which will load the hidden div of the three listbox up. unfortunately, on clicking on the first listbox, the page will call a jquery event which will show the populate the 2nd list box in which the lightbox will close. is there a better way to do this? or i'm not using the proper jquery plugin? i was thinking of putting the whole three panes inside a html file and do ajax call to get the content into that page and load the listbox like that and just use the html popup like a normal popup. Any suggestions? i'm stuck, help!!

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• ASP.NET 2.0 app runs on Win 2003 in IIS 5 isolation mode but not in (default) IIS 6 mode

  - by Tex

  The app uses DLLImport to call a legacy unmanaged dll. Let's call this dll Unmanaged.dll for the sake of this question. Unmanaged.dll has dependencies on 5 other legacy dll's. All of the legacy dll's are placed in the WebApp/bin/ directory of my ASP.NET application. When IIS is running in 5.0 isolation mode, the app works fine - calls to the legacy dll are processed without error. When IIS is running in the default 6.0 mode, the app is able to initiate the Unmanaged.dll (InitMe()), but dies during a later call to it (ProcessString()). I'm pulling my hair out here. I've moved the unmanaged dll's to various locations, tried all kinds of security settings and searched long and hard for a solution. Help! Sample code: [DllImport("Unmanaged.dll", EntryPoint="initME", CharSet=System.Runtime.InteropServices.CharSet.Ansi, CallingConvention=CallingConvention.Cdecl)] internal static extern int InitME(); //Calls to InitMe work fine - Unmanaged.dll initiates and writes some entries in a dedicated log file [DllImport("Unmanaged.dll", EntryPoint="processString", CharSet=System.Runtime.InteropServices.CharSet.Ansi, CallingConvention=CallingConvention.Cdecl)] internal static extern int ProcessString(string inStream, int inLen, StringBuilder outStream, ref int outLen, int maxLen); //Calls to ProcessString cause the app to crash, without leaving much of a trace that I can find so far

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• log4Net EventlogAppender does not work for Asp.Net 2.0 WebSite?

  - by Amitabh

  I have configured log4Net EventLogAppender for Asp.Net 2.0. However it does not log anything. I have following in my Web.Config. <log4net> <appender name="EventLogAppender" type="log4net.Appender.EventLogAppender"> <param name="LogName" value="Test Log" /> <param name="ApplicationName" value="Test-Web" /> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" /> </layout> </appender> <root> <priority value="ERROR"/> <appender-ref ref="EventLogAppender"/> </root> <logger name="NHibernate"> <level value="ERROR" /> <appender-ref ref="EventLogAppender" /> </logger> </log4net> I already have Test-Log Event Log created and AspNet user has permission on the Event Log registry entry. I also have log4Net configured in Global.asax Application_Start. log4net.Config.XmlConfigurator.Configure();

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• Dynamically creating a Generic Type at Runtime

  - by Rick Strahl

  I learned something new today. Not uncommon, but it's a core .NET runtime feature I simply did not know although I know I've run into this issue a few times and worked around it in other ways. Today there was no working around it and a few folks on Twitter pointed me in the right direction. The question I ran into is: How do I create a type instance of a generic type when I have dynamically acquired the type at runtime? Yup it's not something that you do everyday, but when you're writing code that parses objects dynamically at runtime it comes up from time to time. In my case it's in the bowels of a custom JSON parser. After some thought triggered by a comment today I realized it would be fairly easy to implement two-way Dictionary parsing for most concrete dictionary types. I could use a custom Dictionary serialization format that serializes as an array of key/value objects. Basically I can use a custom type (that matches the JSON signature) to hold my parsed dictionary data and then add it to the actual dictionary when parsing is complete. Generic Types at Runtime One issue that came up in the process was how to figure out what type the Dictionary<K,V> generic parameters take. Reflection actually makes it fairly easy to figure out generic types at runtime with code like this: if (arrayType.GetInterface("IDictionary") != null) { if (arrayType.IsGenericType) { var keyType = arrayType.GetGenericArguments()[0]; var valueType = arrayType.GetGenericArguments()[1]; … } } The GetArrayType method gets passed a type instance that is the array or array-like object that is rendered in JSON as an array (which includes IList, IDictionary, IDataReader and a few others). In my case the type passed would be something like Dictionary<string, CustomerEntity>. So I know what the parent container class type is. Based on the the container type using it's then possible to use GetGenericTypeArguments() to retrieve all the generic types in sequential order of definition (ie. string, CustomerEntity). That's the easy part. Creating a Generic Type and Providing Generic Parameters at RunTime The next problem is how do I get a concrete type instance for the generic type? I know what the type name and I have a type instance is but it's generic, so how do I get a type reference to keyvaluepair<K,V> that is specific to the keyType and valueType above? Here are a couple of things that come to mind but that don't work (and yes I tried that unsuccessfully first): Type elementType = typeof(keyvalue<keyType, valueType>); Type elementType = typeof(keyvalue<typeof(keyType), typeof(valueType)>); The problem is that this explicit syntax expects a type literal not some dynamic runtime value, so both of the above won't even compile. I turns out the way to create a generic type at runtime is using a fancy bit of syntax that until today I was completely unaware of: Type elementType = typeof(keyvalue<,>).MakeGenericType(keyType, valueType); The key is the type(keyvalue<,>) bit which looks weird at best. It works however and produces a non-generic type reference. You can see the difference between the full generic type and the non-typed (?) generic type in the debugger: The nonGenericType doesn't show any type specialization, while the elementType type shows the string, CustomerEntity (truncated above) in the type name. Once the full type reference exists (elementType) it's then easy to create an instance. In my case the parser parses through the JSON and when it completes parsing the value/object it creates a new keyvalue<T,V> instance. Now that I know the element type that's pretty trivial with: // Objects start out null until we find the opening tag resultObject = Activator.CreateInstance(elementType); Here the result object is picked up by the JSON array parser which creates an instance of the child object (keyvalue<K,V>) and then parses and assigns values from the JSON document using the types  key/value property signature. Internally the parser then takes each individually parsed item and adds it to a list of  List<keyvalue<K,V>> items. Parsing through a Generic type when you only have Runtime Type Information When parsing of the JSON array is done, the List needs to be turned into a defacto Dictionary<K,V>. This should be easy since I know that I'm dealing with an IDictionary, and I know the generic types for the key and value. The problem is again though that this needs to happen at runtime which would mean using several Convert.ChangeType() calls in the code to dynamically cast at runtime. Yuk. In the end I decided the easier and probably only slightly slower way to do this is a to use the dynamic type to collect the items and assign them to avoid all the dynamic casting madness: else if (IsIDictionary) { IDictionary dict = Activator.CreateInstance(arrayType) as IDictionary; foreach (dynamic item in items) { dict.Add(item.key, item.value); } return dict; } This code creates an instance of the generic dictionary type first, then loops through all of my custom keyvalue<K,V> items and assigns them to the actual dictionary. By using Dynamic here I can side step all the explicit type conversions that would be required in the three highlighted areas (not to mention that this nested method doesn't have access to the dictionary item generic types here). Static <- -> Dynamic Dynamic casting in a static language like C# is a bitch to say the least. This is one of the few times when I've cursed static typing and the arcane syntax that's required to coax types into the right format. It works but it's pretty nasty code. If it weren't for dynamic that last bit of code would have been a pretty ugly as well with a bunch of Convert.ChangeType() calls to litter the code. Fortunately this type of type convulsion is rather rare and reserved for system level code. It's not every day that you create a string to object parser after all :-)© Rick Strahl, West Wind Technologies, 2005-2011Posted in .NET  CSharp   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• How do you display a list of images, from a folder on hard drive, on ASP.NET website?

  - by Jordan S

  I am trying to make a simple photo gallery website. Using ASP.NET and C#. Right now I don't have a server set up but I am just using the development one that Visual Studio Starts when you make a website project and run it. I have a folder on my hard drive that contains an unknown number of images. I want to write a piece of code that will go through each image and add them to the default webpage. I have tried this code but it doesn't work. What am I doing wrong? Should I be using a ListView control or a DataView or something like that? Do I need to add a virtual directory in order to access the images? If so, how do I to that on this test server? ALSO, how do I set the position and alignment of these pictures? For example, how would I make it so that the pictures are in a line vertically and centered on the webpage? protected void Page_Load(object sender, EventArgs e) { string[] filesindirectory = Directory.GetFiles(@"C:\Users\Jordan\Desktop\Web Images"); int i = 1; foreach (string s in filesindirectory) { Image img = new Image(); img.ID = "image" + i.ToString(); img.ImageUrl = s; img.Visible = true; Page.Controls.Add(img); i++; } }

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• Process.Start() and ShellExecute() fails with URLs on Windows 8

  - by Rick Strahl

  Since I installed Windows 8 I've noticed that a number of my applications appear to have problems opening URLs. That is when I click on a link inside of a Windows application, either nothing happens or there's an error that occurs. It's happening both to my own applications and a host of Windows applications I'm running. At first I thought this was an issue with my default browser (Chrome) but after switching the default browser to a few others and experimenting a bit I noticed that the errors occur - oddly enough - only when I run an application as an Administrator. I also tried switching to FireFox and Opera as my default browser and saw exactly the same behavior. The scenario for this is a bit bizarre: Running on Windows 8 Call Process.Start() (or ShellExecute() in Win32 API) with a URL or an HTML file Run 'As Administrator' (works fine under non-elevated user account!) or with UAC off A browser other than Internet Explorer is set as your Default Web Browser Talk about a weird scenario: Something that doesn't work when you run as an Administrator which is supposed to have rights to everything on the system! Instead running under an Admin account - either elevated with a User Account Control prompt or even when running as a full Administrator fails. It appears that this problem does not occur for everyone, but when I looked for a solution to this, I saw quite a few posts in relation to this with no clear resolutions. I have three Windows 8 machines running here in the office and all three of them showed this behavior. Lest you think this is just a programmer's problem - this can affect any software running on your system that needs to run under administrative rights. Try it out Now, in order for this next example to fail, any browser but Internet Explorer has to be your default browser and even then it may not fail depending on how you installed your browser. To see if this is a problem create a small Console application and call Process.Start() with a URL in it:namespace Win8ShellBugConsole { class Program { static void Main(string[] args) { Console.WriteLine("Launching Url..."); Process.Start("http://microsoft.com"); Console.Write("Press any key to continue..."); Console.ReadKey(); Console.WriteLine("\r\n\r\nLaunching image..."); Process.Start(Path.GetFullPath(@"..\..\sailbig.jpg")); Console.Write("Press any key to continue..."); Console.ReadKey(); } } } Compile this code. Then execute the code from Explorer (not from Visual Studio because that may change the permissions). If you simply run the EXE and you're not running as an administrator, you'll see the Web page pop up in the browser as well as the image loading. Now run the same thing with Run As Administrator: Now when you run it you get a nice error when Process.Start() is fired: The same happens if you are running with User Account Control off altogether - ie. you are running as a full admin account. Now if you comment out the URL in the code above and just fire the image display - that works just fine in any user mode. As does opening any other local file type or even starting a new EXE locally (ie. Process.Start("c:\windows\notepad.exe"). All that works, EXCEPT for URLs. The code above uses Process.Start() in .NET but the same happens in Win32 Applications that use the ShellExecute API. In some of my older Fox apps ShellExecute returns an error code of 31 - which is No Shell Association found. What's the Deal? It turns out the problem has to do with the way browsers are registering themselves on Windows. Internet Explorer - being a built-in application in Windows 8 - apparently does this correctly, but other browsers possibly don't or at least didn't at the time I installed them. So even Chrome, which continually updates itself, has a recent version that apparently has this registration issue fixed, I was unable to simply set IE as my default browser then use Chrome to 'Set as Default Browser'. It still didn't work. Neither did using the Set Program Associations dialog which lets you assign what extensions are mapped to by a given application. Each application provides a set of extension/moniker mappings that it supports and this dialog lets you associate them on a system wide basis. This also did not work for Chrome or any of the other browsers at first. However, after repeated retries here eventually I did manage to get FireFox to work, but not any of the others. What Works? Reinstall the Browser In the end I decided on the hard core pull the plug solution: Totally uninstall and re-install Chrome in this case. And lo and behold, after reinstall everything was working fine. Now even removing the association for Chrome, switching to IE as the default browser and then back to Chrome works. But, even though the version of Chrome I was running before uninstalling and reinstalling is the same as I'm running now after the reinstall now it works. Of course I had to find out the hard way, before Richard commented with a note regarding what the issue is with Chrome at least: http://code.google.com/p/chromium/issues/detail?id=156400 As expected the issue is a registration issue - with keys not being registered at the machine level. Reading this I'm still not sure why this should be a problem - an elevated account still runs under the same user account (ie. I'm still rickstrahl even if I Run As Administrator), so why shouldn't an app be able to read my Current User registry hive? And also that doesn't quite explain why if I register the extensions using Run As Administrator in Chrome when using Set as Default Browser). But in the end it works… Not so fast It's now a couple of days later and still there are some oddball problems although this time they appear to be purely Chrome issues. After the reinstall Chrome seems to pop up properly with ShellExecute() calls both in regular user and Admin mode. However, it now looks like Chrome is actually running two completely separate user profiles for each. For example, when I run Visual Studio in Admin mode and go to View in browser, Chrome complains that it was installed in Admin mode and can't launch (WTF?). Then you retry a few times later and it ends up working. When launched that way some of the plug-ins installed don't show up with the effect that sometimes they're visible sometimes they're not. Also Chrome seems to loose my configuration and Google sign in between sessions now, presumably when switching user modes. Add-ins installed in admin mode don't show up in user mode and vice versa. Ah, this is lovely. Did I mention that I freaking hate UAC precisely because of this kind of bullshit. You can never tell exactly what account your app is running under, and apparently apps also have a hard time trying to put data into the right place that works for both scenarios. And as my recent post on using Windows Live accounts shows it's yet another level of abstraction ontop of the underlying system identity that can cause all sort of small side effect headaches like this. Hopefully, most of you are skirting this issue altogether - having installed more recent versions of your favorite browsers. If not, hopefully this post will take you straight to reinstallation to fix this annoying issue.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Windows  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Can't hit breakpoint in ASP.NET web app (Stop debugging in progress... popup in VS)

  - by dotnetdev

  Hi, I am trying to debug some code in my ASP.NET web app. I set a breakpoint in one of the page events of the page's codebehind, and this once came up with a special icon in place of the red breakpoint saying symbols have not been loaded and the breakpoint will not be hit. This error has not repeated itself but why can't I hit the breakpoint? Also, when I press stop, I get a popup in VS stating: Stop Debugging In Progres... Debugging is being stopped but is not yet complete. You can force debugging to stop completely, but any processes attached may terminate. This window will automatically close when debugging has completely stopped. Completely stop I also don't get the website appear in my browser either when starting to debug. :( To make things worse, I have a line of code like this in my page's codebehind: RssFeedSites = opml.Parse(filestream); I am putting the problematic breakpoint on this line. But I have a programatic breakpoint in the Parse() method of opml, but this does not get hit, either. Thanks

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• What's the strangest corner case you've seen in C# or .NET?

  - by Jon Skeet

  I collect a few corner cases and brain teasers and would always like to hear more. The page only really covers C# language bits and bobs, but I also find core .NET things interesting too. For example, here's one which isn't on the page, but which I find incredible: string x = new string(new char[0]); string y = new string(new char[0]); Console.WriteLine(object.ReferenceEquals(x, y)); I'd expect that to print False - after all, "new" (with a reference type) always creates a new object, doesn't it? The specs for both C# and the CLI indicate that it should. Well, not in this particular case. It prints True, and has done on every version of the framework I've tested it with. (I haven't tried it on Mono, admittedly...) Just to be clear, this is only an example of the kind of thing I'm looking for - I wasn't particularly looking for discussion/explanation of this oddity. (It's not the same as normal string interning; in particular, string interning doesn't normally happen when a constructor is called.) I was really asking for similar odd behaviour. Any other gems lurking out there?

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• How to use Castle Windsor with ASP.Net web forms?

  - by Xian

  I am trying to wire up dependency injection with Windsor to standard asp.net web forms. I think I have achieved this using a HttpModule and a CustomAttribute (code shown below), although the solution seems a little clunky and was wondering if there is a better supported solution out of the box with Windsor? There are several files all shown together here // index.aspx.cs public partial class IndexPage : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Logger.Write("page loading"); } [Inject] public ILogger Logger { get; set; } } // WindsorHttpModule.cs public class WindsorHttpModule : IHttpModule { private HttpApplication _application; private IoCProvider _iocProvider; public void Init(HttpApplication context) { _application = context; _iocProvider = context as IoCProvider; if(_iocProvider == null) { throw new InvalidOperationException("Application must implement IoCProvider"); } _application.PreRequestHandlerExecute += InitiateWindsor; } private void InitiateWindsor(object sender, System.EventArgs e) { Page currentPage = _application.Context.CurrentHandler as Page; if(currentPage != null) { InjectPropertiesOn(currentPage); currentPage.InitComplete += delegate { InjectUserControls(currentPage); }; } } private void InjectUserControls(Control parent) { if(parent.Controls != null) { foreach (Control control in parent.Controls) { if(control is UserControl) { InjectPropertiesOn(control); } InjectUserControls(control); } } } private void InjectPropertiesOn(object currentPage) { PropertyInfo[] properties = currentPage.GetType().GetProperties(); foreach(PropertyInfo property in properties) { object[] attributes = property.GetCustomAttributes(typeof (InjectAttribute), false); if(attributes != null && attributes.Length > 0) { object valueToInject = _iocProvider.Container.Resolve(property.PropertyType); property.SetValue(currentPage, valueToInject, null); } } } } // Global.asax.cs public class Global : System.Web.HttpApplication, IoCProvider { private IWindsorContainer _container; public override void Init() { base.Init(); InitializeIoC(); } private void InitializeIoC() { _container = new WindsorContainer(); _container.AddComponent<ILogger, Logger>(); } public IWindsorContainer Container { get { return _container; } } } public interface IoCProvider { IWindsorContainer Container { get; } }

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• How do I manage application configuration in ASP.NET?

  - by GlennS

  I am having difficulty with managing configuration of an ASP.Net application to deploy for different clients. The sheer volume of different settings which need twiddling takes up large amounts of time, and the current configuration methods are too complicated to enable us to push this responsibility out to support partners. Any suggestions for better methods to handle this or good sources of information to research? How we do things at present: Various xml configuration files which are referenced in Web.Config, for example an AppSettings.xml. Configurations for specific sites are kept in duplicate configuration files. Text files containing lists of data specific to the site In some cases, manual one-off changes to the database C# configuration for Windsor IOC. The specific issues we are having: Different sites with different features enabled, different external services we have to talk to and different business rules. Different deployment types (live, test, training) Configuration keys change across versions (get added, remove), meaning we have to update all the duplicate files We still need to be able to alter keys while the application is running Our current thoughts on how we might approach this are: Move the configuration into dynamically compiled code (possibly Boo, Binsor or JavaScript) Have some form of diffing/merging configuration: combine a default config with a live/test/training config and a site-specific config

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• How can I make a server log file available via my ASP.NET MVC website?

  - by Gary McGill

  I have an ASP.NET MVC website that works in tandem with a Windows Service that processes file uploads. For easy maintenance of the site, I'd like the log file for the Windows Service to be accessible (to me, only) via the website, so that I can hit http://myserver/logs/myservice to view the contents of the log file. How can I do that? At a guess, I could either have the service write its log file in a "Logs" folder at the top level of the site, or I could leave it where it is and set up a virtual directory to point to it. Which of these is better - or is there another, better way? Wherever the file is stored, I can see that there's going to be another problem. I tried out the first option (Logs folder in my website), but when I try to access the file via HTTP I get an error: The process cannot access the file 'foo' because it is being used by another process. Now, I know from experience that my service keeps the file locked for writing while it's running, but that I can still open the file in Notepad to view the current contents. (I'm surprised that IIS insists on write access, if that's what's happening). How can I get around that? Do I really have to write a handler to read the file and serve it to the browser myself? Or can I fix this with configuration or somesuch? PS. I'm using IIS7 if that helps.

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• Adding proper THEAD sections to a GridView

  - by Rick Strahl

  I’m working on some legacy code for a customer today and dealing with a page that has my favorite ‘friend’ on it: A GridView control. The ASP.NET GridView control (and also the older DataGrid control) creates some pretty messed up HTML. One of the more annoying things it does is to generate all rows including the header into the page in the <tbody> section of the document rather than in a properly separated <thead> section. Here’s is typical GridView generated HTML output: <table class="tablesorter blackborder" cellspacing="0" rules="all" border="1" id="Table1" style="border-collapse:collapse;"> <tr> <th scope="col">Name</th> <th scope="col">Company</th> <th scope="col">Entered</th><th scope="col">Balance</th> </tr> <tr> <td>Frank Hobson</td><td>Hobson Inc.</td> <td>10/20/2010 12:00:00 AM</td><td>240.00</td> </tr> ... </table> Notice that all content – both the headers and the body of the table – are generated directly under the <table> tag and there’s no explicit use of <tbody> or <thead> (or <tfooter> for that matter). When the browser renders this the document some default settings kick in and the DOM tree turns into something like this: <table> <tbody> <tr> <-- header <tr> <—detail row <tr> <—detail row </tbody> </table> Now if you’re just rendering the Grid server side and you’re applying all your styles through CssClass assignments this isn’t much of a problem. However, if you want to style your grid more generically using hierarchical CSS selectors it gets a lot more tricky to format tables that don’t properly delineate headers and body content. Also many plug-ins and other JavaScript utilities that work on tables require a properly formed table layout, and many of these simple won’t work out of the box with a GridView. For example, one of the things I wanted to do for this app is use the jQuery TableSorter plug-in which – not surprisingly – requires to work of table headers in the DOM document. Out of the box, the TableSorter plug-in doesn’t work with GridView controls, because the lack of a <thead> section to work on. Luckily with a little help of some jQuery scripting there’s a real easy fix to this problem. Basically, if we know the GridView generated table has a header in it, code like the following will move the headers from <tbody> to <thead>: <script type="text/javascript"> $(document).ready(function () { // Fix up GridView to support THEAD tags $("#gvCustomers tbody").before("<thead><tr></tr></thead>"); $("#gvCustomers thead tr").append($("#gvCustomers th")); $("#gvCustomers tbody tr:first").remove(); $("#gvCustomers").tablesorter({ sortList: [[1, 0]] }); }); </script> And voila you have a table that now works with the TableSorter plug-in. If you use GridView’s a lot you might want something a little more generic so the following does the same thing but should work more generically on any GridView/DataGrid missing its <thead> tag: function fixGridView(tableEl) {            var jTbl = $(tableEl);         if(jTbl.find("tbody>tr>th").length > 0) {         jTbl.find("tbody").before("<thead><tr></tr></thead>");         jTbl.find("thead tr").append(jTbl.find("th"));         jTbl.find("tbody tr:first").remove();     } } which you can call like this: $(document).ready(function () { fixGridView( $("#gvCustomers") ); $("#gvCustomers").tablesorter({ sortList: [[1, 0]] }); }); Server Side THEAD Rendering [updated from comments 11/21/2010] Several commenters pointed out that you can also do this on the server side by using the GridView.HeaderRow.TableSection property to force rendering with a proper table header. I was unaware of this option actually – not exactly an easy one to discover. One issue here is that timing of this needs to happen during the databinding process so you need to use an event handler: this.gvCustomers.DataBound += (object o, EventArgs ev) => { gvCustomers.HeaderRow.TableSection = TableRowSection.TableHeader; }; this.gvCustomers.DataSource = custList; this.gvCustomers.DataBind(); You can apply the same logic for the FooterRow. It’s beyond me why this rendering mode isn’t the default for a GridView – why would you ever want to have a table that doesn’t use a THEAD section??? But I disgress :-) I don’t use GridViews much anymore – opting for more flexible approaches using ListViews or even plain code based views or other custom displays that allow more control over layout, but I still see a lot of old code that does use them old clunkers including my own :) (gulp) and this does make life a little bit easier especially if you’re working with any of the jQuery table related plug-ins that expect a proper table structure.© Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  jQuery  

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• Asp.Net MVC 2: How exactly does a view model bind back to the model upon post back?

  - by Dr. Zim

  Sorry for the length, but a picture is worth 1000 words: In ASP.NET MVC 2, the input form field "name" attribute must contain exactly the syntax below that you would use to reference the object in C# in order to bind it back to the object upon post back. That said, if you have an object like the following where it contains multiple Orders having multiple OrderLines, the names would look and work well like this (case sensitive): This works: Order[0].id Order[0].orderDate Order[0].Customer.name Order[0].Customer.Address Order[0].OrderLine[0].itemID // first order line Order[0].OrderLine[0].description Order[0].OrderLine[0].qty Order[0].OrderLine[0].price Order[0].OrderLine[1].itemID // second order line, same names Order[0].OrderLine[1].description Order[0].OrderLine[1].qty Order[0].OrderLine[1].price However we want to add order lines and remove order lines at the client browser. Apparently, the indexes must start at zero and contain every consecutive index number to N. The black belt ninja Phil Haack's blog entry here explains how to remove the [0] index, have duplicate names, and let MVC auto-enumerate duplicate names with the [0] notation. However, I have failed to get this to bind back using a nested object: This fails: Order.id // Duplicate names should enumerate at 0 .. N Order.orderDate Order.Customer.name Order.Customer.Address Order.OrderLine.itemID // And likewise for nested properties? Order.OrderLine.description Order.OrderLine.qty Order.OrderLine.price Order.OrderLine.itemID Order.OrderLine.description Order.OrderLine.qty Order.OrderLine.price I haven't found any advice out there yet that describes how this works for binding back nested ViewModels on post. Any links to existing code examples or strict examples on the exact names necessary to do nested binding with ILists? Steve Sanderson has code that does this sort of thing here, but we cannot seem to get this to bind back to nested objects. Anything not having the [0]..[n] AND being consecutive in numbering simply drops off of the return object. Any ideas?

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• Is there a way in .NET to access the bytecode/IL/CLR that is currently running?

  - by Alix

  Hi. I'd like to have access to the bytecode that is currently running or about to run in order to detect certain instructions and take specific actions (depending the instructions). In short, I'd like to monitor the bytecode in order to add safety control. Is this possible? I know there are some AOP frameworks that notify you of specific events, like an access to a field or the invocation of a method, but I'd like to skip that extra layer and just look at all the bytecode myself, throughout the entire execution of the application. I've already looked at the following questions (...among many many others ;) ):     Preprocessing C# - Detecting Methods     What CLR/.NET bytecode tools exist? as well as several AOP frameworks (although not in great detail, since they don't seem to do quite what I need) and I'm familiar with Mono.Cecil. I appreciate alternative suggestions, but I don't want to introduce the overhead of an AOP framework when what I actually need is access to the bytecode, without all the stuff they add on top to make it more user-friendly (... admittedly very useful stuff when you don't want to go low-level). Thanks :)

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