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  • Prroblem with ObjectDelete() in Entity Framework 4

    - by Tom
    I got two entities: public class User : Entity { public virtual string Username { get; set; } public virtual string Email { get; set; } public virtual string PasswordHash { get; set; } public virtual List<Photo> Photos { get; set; } } and public class Photo : Entity { public virtual string FileName { get; set; } public virtual string Thumbnail { get; set; } public virtual string Description { get; set; } public virtual int UserId { get; set; } public virtual User User { get; set; } } When I try to delete the photo it works fine for the DB (record gets romoved from the table) but it doesnt for the Photos collection in the User entity (I can still see that photo in user.Photos). This is my code. What I'm doing wrong here? Changing entity properties works fine. When I change photo FileName for example it gets updated in DB and in user.Photos. var photo = SelectById(id); Context.DeleteObject(photo); Context.SaveChanges(); var user = GetUser(userName); // the photo I have just deleted is still in user.Photos also tried this but getting same results: var photo = user.Photos.First(); Context.DeleteObject(photo); Context.SaveChanges();

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  • Handling duplicate insertion

    - by Francis
    So I've got this piece of code which, logically should work but Entity Framework is behaving unexpectedly. Here: foreach (SomeClass someobject in allObjects) { Supplier supplier = new Supplier(); supplier.primary_key = someobject.id; supplier.name = someobject.displayname; try { sm.Add(supplier); ro.Created++; } catch (Exception ex) { ro.Error++; } } Here's what I have in sm.Add() public Supplier Add(Supplier supplier) { try { _ctx.AddToSupplier(supplier); _ctx.SaveChanges(); return supplier; } catch (Exception ex) { throw; } } I can have records in allObjects that have the same id. My piece of code needs to support this and just move on to the next and try to insert it, which I think should work. If this happens, an exception is throw, saying that records with dupe PKs cannot be inserted (of course). The exception mentions the value of the PK, for example 1000. All is well, a new supplier is passed to sm.Add() containing a PK that's never been used before. (1001) Weirdly though, when doing SaveChanges(), EF will whine about not being able to insert records with dupe PKs. The exception still mentions 1000 even though supplier contains 10001 in primary_key. I feel this is me not using _ctx properly. Do I need to call something else to sync it ?

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  • Database doesn't update using TransactionScope

    - by Dissonant
    I have a client trying to communicate with a WCF service in a transactional manner. The client passes some data to the service and the service adds the data to its database accordingly. For some reason, the new data the service submits to its database isn't being persisted. When I have a look at the table data in the Server Explorer no new rows are added... Relevant code snippets are below: Client static void Main() { MyServiceClient client = new MyServiceClient(); Console.WriteLine("Please enter your name:"); string name = Console.ReadLine(); Console.WriteLine("Please enter the amount:"); int amount = int.Parse(Console.ReadLine()); using (TransactionScope transaction = new TransactionScope(TransactionScopeOption.Required)) { client.SubmitData(amount, name); transaction.Complete(); } client.Close(); } Service Note: I'm using Entity Framework to persist objects to the database. [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)] public void SubmitData(int amount, string name) { DatabaseEntities db = new DatabaseEntities(); Payment payment = new Payment(); payment.Amount = amount; payment.Name = name; db.AddToPayment(payment); //add to Payment table db.SaveChanges(); db.Dispose(); } I'm guessing it has something to do with the TransactionScope being used in the client. I've tried all combinations of db.SaveChanges() and db.AcceptAllChanges() as well, but the new payment data just doesn't get added to the database!

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  • Saving a single entity instead of the entire context - revisited

    - by nite
    I’m looking for a way to have fine grained control over what is saved using Entity Framework, rather than the whole ObjectContext.SaveChanges(). My scenario is pretty straight forward, and I’m quite amazed not catered for in EF – pretty basic in NHibernate and all other data access paradigms I’ve seen. I’m generating a bunch of data (in a WPF UI) and allowing the user to fine tune what is proposed and choose what is actually committed to the database. For the proposed entities I’m: getting a bunch of reference entities (eg languages) via my objectcontext, creating the proposed entities and assigning these reference entities to them (as navigation properties), so by virtue of their relationship to the reference entities they’re implicitly added to the objectconext Trying to create & save individual entites based on the proposed entities. I figure this should be really simple & trivial but everything I’ve tried I’ve hit a brick wall, either I set up another objectcontext & add just the entity I need (it then tries to add the whole graph and fails as it’s on another objectcontext). I’ve tried MergeOptions = NoTracking on my reference entities to try to get the Attach/AddObject not to navigate through these to create a graph, no avail. I've removed the navigation properties from the reference entities. I've tried AcceptAllChanges, that works but pretty useless in practice as I do still want to track & save other entities. In a simple test, I can create 2 of my proposed entities, AddObject the one I want to save and then Detach the one I dont then call SaveChanges, this works but again not great in practice. Following are a few links to some of the nifty ideas which in the end don’t help in the end but illustrate the complexity of EF for something so simple. I’m really looking for a SaveSingle/SaveAtomic method, and think it’s a pretty reasonable & basic ask for any DAL, letalone a cutting edge ORM. http://stackoverflow.com/questions/1301460/saving-a-single-entity-instead-of-the-entire-context www.codeproject.com/KB/architecture/attachobjectgraph.aspx?fid=1534536&df=90&mpp=25&noise=3&sort=Position&view=Quick&select=3071122&fr=1 bernhardelbl.spaces.live.com/blog/cns!DB54AE2C5D84DB78!238.entry

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  • Why do I get this exception? {An item with the same key has already been added."})

    - by Alan
    Aknittel NewSellerID is the result of a lookup on tblSellers. These tables (tblSellerListings and tblSellers) are not "officially" joined with a foreign key relationship, either in the model or in the database, but I want some referential integrity maintained for the future. So my issue remains. Why do I get the exception ({"An item with the same key has already been added."}) with this code, if I don't begin each iteration of the foreach loop with a new ObjectContext and end it with SaveChanges, which I think will affect performance. Also, could you tell me why ORCSolutionsDataService.tblSellerListings (An ADO.NET DataServices/WCF object is not IDisposable, like LINQ to Entities?? ============================================== // Add listings to previous seller int NewSellerID = 0; // Look up existing Seller key using SellerUniqueEBAYID var qryCurrentSeller = from s in service.tblSellers where s.SellerEBAYUserID == SellerUserID select s; foreach (var s in qryCurrentSeller) NewSellerID = s.SellerID; // Save the selected listings for this seller foreach (DataGridViewRow dgr in dgvRows) { ORCSolutionsDataService.tblSellerListings NewSellerListing = new ORCSolutionsDataService.tblSellerListings(); NewSellerListing.ItemID = dgr.Cells["txtSellerItemID"].Value.ToString(); NewSellerListing.Title = dgr.Cells["txtSellerItemTitle"].Value.ToString(); NewSellerListing.CurrentPrice = Convert.ToDecimal(dgr.Cells["txtSellerItemPrice"].Value); NewSellerListing.QuantitySold = Convert.ToInt32(dgr.Cells["txtSellerItemSold"].Value); NewSellerListing.EndTime = Convert.ToDateTime(dgr.Cells["txtSellerItemEnds"].Value); NewSellerListing.CategoryName = dgr.Cells["txtSellerItemCategory"].Value.ToString(); NewSellerListing.ExtendedPrice = Convert.ToDecimal(dgr.Cells["txtExtendedReceipts"].Value); NewSellerListing.RetrievedDtime = Convert.ToDateTime(dtSellerDataRetrieved.ToString()); NewSellerListing.SellerID = NewSellerID; service.AddTotblSellerListings(NewSellerListing); } service.SaveChanges(); } catch (Exception ex) { MessageBox.Show("Unable to add a new case. Exception: " + ex.Message); }

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  • Why newly created entity object with navigation property is automaticly added to ObjectContext?

    - by Levelbit
    I have to entities: Company and Location (one to many). When I create new Location entity object and assign navigation property(Company) with the navigation property of already existing Location object (Location _new = new Location(); _new.Company = _old.Company). It seems that at that point newly created object is added to Object Context automatically, because when I call SaveChanges method that object is insert to database although I didn't call ObjectContext.AddObject(_new). I'm new in EF so there is probably reason why I have result like this? Is there need to assign also CompanyReference filed too and how to do it? IDaoFactory daoFactory = new DaoFactory(); ILocationDao locaitonDao = daoFactory.GetLocationDao(); IEnumerable<Location> locations = locaitonDao.GetLocations(); Location _old = locations.First(); Location _new = new Location(); _new.LocationName = _old.LocationName; _new.Company = _old.Company;// 1 _new.Address = _old.Address; //... ContactEntities.SaveChanges();//2 If I execute line (1) instantly _new object is added to object context and I can see additional datarow in my datagrid after line (2) is executed.

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  • can't edit my h:datatable

    - by Mike
    hi! i have this code: <h:form> <rich:dataTable value="#{my.lreqs}" var="req" id="reqs" width="630px" > <rich:column label="Value" styleClass="schColL" width="90px" style="text-align:center"> <f:facet name="header"> <h:outputText value="#{my.colValue}" /> </f:facet> <h:inputText value="#{req.value}" > </h:inputText> </rich:column> </rich:dataTable> <h:commandButton value="Save" action="#{my.saveChanges}" ></h:commandButton> </h:form> and this is my bean: private List<Detail> lreqs; public List<Detail> getLreqs() { return lreqs; } public void setLreqs(List<Detail> lreqs) { this.lreqs = lreqs; } public void saveChanges() { firstNewValue = lreqs.get(0).getValue(); } but when i click save - a new value in req.value field is not being saved! why is it?

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  • Does Entity Framework saves related classes automatically?

    - by herbatnic
    Let's assume that we have such classes public class A{ string someField { get; set; } public virtual B B {get; set; } } public class B { int someIntField {get; set; } [ForeignKey("Id")] [Required] public virtual A A { get; set; } } In code I create new instances for both of them and making relation like: A a = new A () { someField = "abcd"}; B b = new B () { someIntField = 42 }; A.B = b; B.A = a; Should I using DBContext to save both classes like that: using (var db = new myDbContext()) { myDbContext.As.Add(A); myDbContext.Bs.Add(B); myDBContext.SaveChanges(); } Or saving it like that: using (var db = new myDbContext()) { myDbContext.As.Add(A); myDbContext.SaveChanges(); } is enough to store related objects into database?

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  • Prevent cached objects to end up in the database with Entity Framework

    - by Dirk Boer
    We have an ASP.NET project with Entity Framework and SQL Azure. A big part of our data only needs to be updated a few times a day, other data is very volatile. The data that barely changes we cache in memory at startup, detach from the context and than use it mainly for reading, drastically lowering the amount of database requests we have to do. The volatile data is requested everytime by a DbContext per Http request. When we do an update to the cached data, we send a message to all instances to catch a fresh version of all the data from the SQL server. So far, so good. Until we introduced a bug that linked one of these 'cached' objects to the 'volatile' data, and did a SaveChanges. Well, that was quite a mess. The whole data tree was added again and again by every update, corrupting the whole database with a whole lot of duplicated data. As a complete hack I added a completely arbitrary column with a UniqueConstraint and some gibberish data on one of the root tables; hopefully failing the SaveChanges() next time we introduce such a bug because it will violate the Unique Constraint. But it is of course hacky, and I'm still pretty scared ;P Are there any better ways to prevent whole tree's of cached objects ending up in the database? More information Project is ASP.NET MVC I cache this data, because it is mainly read only, and this saves a tons of extra database calls per http request

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  • Announcing Entity Framework Code-First (CTP5 release)

    - by ScottGu
    This week the data team released the CTP5 build of the new Entity Framework Code-First library.  EF Code-First enables a pretty sweet code-centric development workflow for working with data.  It enables you to: Develop without ever having to open a designer or define an XML mapping file Define model objects by simply writing “plain old classes” with no base classes required Use a “convention over configuration” approach that enables database persistence without explicitly configuring anything Optionally override the convention-based persistence and use a fluent code API to fully customize the persistence mapping I’m a big fan of the EF Code-First approach, and wrote several blog posts about it this summer: Code-First Development with Entity Framework 4 (July 16th) EF Code-First: Custom Database Schema Mapping (July 23rd) Using EF Code-First with an Existing Database (August 3rd) Today’s new CTP5 release delivers several nice improvements over the CTP4 build, and will be the last preview build of Code First before the final release of it.  We will ship the final EF Code First release in the first quarter of next year (Q1 of 2011).  It works with all .NET application types (including both ASP.NET Web Forms and ASP.NET MVC projects). Installing EF Code First You can install and use EF Code First CTP5 using one of two ways: Approach 1) By downloading and running a setup program.  Once installed you can reference the EntityFramework.dll assembly it provides within your projects.      or: Approach 2) By using the NuGet Package Manager within Visual Studio to download and install EF Code First within a project.  To do this, simply bring up the NuGet Package Manager Console within Visual Studio (View->Other Windows->Package Manager Console) and type “Install-Package EFCodeFirst”: Typing “Install-Package EFCodeFirst” within the Package Manager Console will cause NuGet to download the EF Code First package, and add it to your current project: Doing this will automatically add a reference to the EntityFramework.dll assembly to your project:   NuGet enables you to have EF Code First setup and ready to use within seconds.  When the final release of EF Code First ships you’ll also be able to just type “Update-Package EFCodeFirst” to update your existing projects to use the final release. EF Code First Assembly and Namespace The CTP5 release of EF Code First has an updated assembly name, and new .NET namespace: Assembly Name: EntityFramework.dll Namespace: System.Data.Entity These names match what we plan to use for the final release of the library. Nice New CTP5 Improvements The new CTP5 release of EF Code First contains a bunch of nice improvements and refinements. Some of the highlights include: Better support for Existing Databases Built-in Model-Level Validation and DataAnnotation Support Fluent API Improvements Pluggable Conventions Support New Change Tracking API Improved Concurrency Conflict Resolution Raw SQL Query/Command Support The rest of this blog post contains some more details about a few of the above changes. Better Support for Existing Databases EF Code First makes it really easy to create model layers that work against existing databases.  CTP5 includes some refinements that further streamline the developer workflow for this scenario. Below are the steps to use EF Code First to create a model layer for the Northwind sample database: Step 1: Create Model Classes and a DbContext class Below is all of the code necessary to implement a simple model layer using EF Code First that goes against the Northwind database: EF Code First enables you to use “POCO” – Plain Old CLR Objects – to represent entities within a database.  This means that you do not need to derive model classes from a base class, nor implement any interfaces or data persistence attributes on them.  This enables the model classes to be kept clean, easily testable, and “persistence ignorant”.  The Product and Category classes above are examples of POCO model classes. EF Code First enables you to easily connect your POCO model classes to a database by creating a “DbContext” class that exposes public properties that map to the tables within a database.  The Northwind class above illustrates how this can be done.  It is mapping our Product and Category classes to the “Products” and “Categories” tables within the database.  The properties within the Product and Category classes in turn map to the columns within the Products and Categories tables – and each instance of a Product/Category object maps to a row within the tables. The above code is all of the code required to create our model and data access layer!  Previous CTPs of EF Code First required an additional step to work against existing databases (a call to Database.Initializer<Northwind>(null) to tell EF Code First to not create the database) – this step is no longer required with the CTP5 release.  Step 2: Configure the Database Connection String We’ve written all of the code we need to write to define our model layer.  Our last step before we use it will be to setup a connection-string that connects it with our database.  To do this we’ll add a “Northwind” connection-string to our web.config file (or App.Config for client apps) like so:   <connectionStrings>          <add name="Northwind"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\northwind.mdf;User Instance=true"          providerName="System.Data.SqlClient" />   </connectionStrings> EF “code first” uses a convention where DbContext classes by default look for a connection-string that has the same name as the context class.  Because our DbContext class is called “Northwind” it by default looks for a “Northwind” connection-string to use.  Above our Northwind connection-string is configured to use a local SQL Express database (stored within the \App_Data directory of our project).  You can alternatively point it at a remote SQL Server. Step 3: Using our Northwind Model Layer We can now easily query and update our database using the strongly-typed model layer we just built with EF Code First. The code example below demonstrates how to use LINQ to query for products within a specific product category.  This query returns back a sequence of strongly-typed Product objects that match the search criteria: The code example below demonstrates how we can retrieve a specific Product object, update two of its properties, and then save the changes back to the database: EF Code First handles all of the change-tracking and data persistence work for us, and allows us to focus on our application and business logic as opposed to having to worry about data access plumbing. Built-in Model Validation EF Code First allows you to use any validation approach you want when implementing business rules with your model layer.  This enables a great deal of flexibility and power. Starting with this week’s CTP5 release, EF Code First also now includes built-in support for both the DataAnnotation and IValidatorObject validation support built-into .NET 4.  This enables you to easily implement validation rules on your models, and have these rules automatically be enforced by EF Code First whenever you save your model layer.  It provides a very convenient “out of the box” way to enable validation within your applications. Applying DataAnnotations to our Northwind Model The code example below demonstrates how we could add some declarative validation rules to two of the properties of our “Product” model: We are using the [Required] and [Range] attributes above.  These validation attributes live within the System.ComponentModel.DataAnnotations namespace that is built-into .NET 4, and can be used independently of EF.  The error messages specified on them can either be explicitly defined (like above) – or retrieved from resource files (which makes localizing applications easy). Validation Enforcement on SaveChanges() EF Code-First (starting with CTP5) now automatically applies and enforces DataAnnotation rules when a model object is updated or saved.  You do not need to write any code to enforce this – this support is now enabled by default.  This new support means that the below code – which violates our above rules – will automatically throw an exception when we call the “SaveChanges()” method on our Northwind DbContext: The DbEntityValidationException that is raised when the SaveChanges() method is invoked contains a “EntityValidationErrors” property that you can use to retrieve the list of all validation errors that occurred when the model was trying to save.  This enables you to easily guide the user on how to fix them.  Note that EF Code-First will abort the entire transaction of changes if a validation rule is violated – ensuring that our database is always kept in a valid, consistent state. EF Code First’s validation enforcement works both for the built-in .NET DataAnnotation attributes (like Required, Range, RegularExpression, StringLength, etc), as well as for any custom validation rule you create by sub-classing the System.ComponentModel.DataAnnotations.ValidationAttribute base class. UI Validation Support A lot of our UI frameworks in .NET also provide support for DataAnnotation-based validation rules. For example, ASP.NET MVC, ASP.NET Dynamic Data, and Silverlight (via WCF RIA Services) all provide support for displaying client-side validation UI that honor the DataAnnotation rules applied to model objects. The screen-shot below demonstrates how using the default “Add-View” scaffold template within an ASP.NET MVC 3 application will cause appropriate validation error messages to be displayed if appropriate values are not provided: ASP.NET MVC 3 supports both client-side and server-side enforcement of these validation rules.  The error messages displayed are automatically picked up from the declarative validation attributes – eliminating the need for you to write any custom code to display them. Keeping things DRY The “DRY Principle” stands for “Do Not Repeat Yourself”, and is a best practice that recommends that you avoid duplicating logic/configuration/code in multiple places across your application, and instead specify it only once and have it apply everywhere. EF Code First CTP5 now enables you to apply declarative DataAnnotation validations on your model classes (and specify them only once) and then have the validation logic be enforced (and corresponding error messages displayed) across all applications scenarios – including within controllers, views, client-side scripts, and for any custom code that updates and manipulates model classes. This makes it much easier to build good applications with clean code, and to build applications that can rapidly iterate and evolve. Other EF Code First Improvements New to CTP5 EF Code First CTP5 includes a bunch of other improvements as well.  Below are a few short descriptions of some of them: Fluent API Improvements EF Code First allows you to override an “OnModelCreating()” method on the DbContext class to further refine/override the schema mapping rules used to map model classes to underlying database schema.  CTP5 includes some refinements to the ModelBuilder class that is passed to this method which can make defining mapping rules cleaner and more concise.  The ADO.NET Team blogged some samples of how to do this here. Pluggable Conventions Support EF Code First CTP5 provides new support that allows you to override the “default conventions” that EF Code First honors, and optionally replace them with your own set of conventions. New Change Tracking API EF Code First CTP5 exposes a new set of change tracking information that enables you to access Original, Current & Stored values, and State (e.g. Added, Unchanged, Modified, Deleted).  This support is useful in a variety of scenarios. Improved Concurrency Conflict Resolution EF Code First CTP5 provides better exception messages that allow access to the affected object instance and the ability to resolve conflicts using current, original and database values.  Raw SQL Query/Command Support EF Code First CTP5 now allows raw SQL queries and commands (including SPROCs) to be executed via the SqlQuery and SqlCommand methods exposed off of the DbContext.Database property.  The results of these method calls can be materialized into object instances that can be optionally change-tracked by the DbContext.  This is useful for a variety of advanced scenarios. Full Data Annotations Support EF Code First CTP5 now supports all standard DataAnnotations within .NET, and can use them both to perform validation as well as to automatically create the appropriate database schema when EF Code First is used in a database creation scenario.  Summary EF Code First provides an elegant and powerful way to work with data.  I really like it because it is extremely clean and supports best practices, while also enabling solutions to be implemented very, very rapidly.  The code-only approach of the library means that model layers end up being flexible and easy to customize. This week’s CTP5 release further refines EF Code First and helps ensure that it will be really sweet when it ships early next year.  I recommend using NuGet to install and give it a try today.  I think you’ll be pleasantly surprised by how awesome it is. Hope this helps, Scott

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  • ASP.NET and HTML5 Local Storage

    - by Stephen Walther
    My favorite feature of HTML5, hands-down, is HTML5 local storage (aka DOM storage). By taking advantage of HTML5 local storage, you can dramatically improve the performance of your data-driven ASP.NET applications by caching data in the browser persistently. Think of HTML5 local storage like browser cookies, but much better. Like cookies, local storage is persistent. When you add something to browser local storage, it remains there when the user returns to the website (possibly days or months later). Importantly, unlike the cookie storage limitation of 4KB, you can store up to 10 megabytes in HTML5 local storage. Because HTML5 local storage works with the latest versions of all modern browsers (IE, Firefox, Chrome, Safari), you can start taking advantage of this HTML5 feature in your applications right now. Why use HTML5 Local Storage? I use HTML5 Local Storage in the JavaScript Reference application: http://Superexpert.com/JavaScriptReference The JavaScript Reference application is an HTML5 app that provides an interactive reference for all of the syntax elements of JavaScript (You can read more about the application and download the source code for the application here). When you open the application for the first time, all of the entries are transferred from the server to the browser (all 300+ entries). All of the entries are stored in local storage. When you open the application in the future, only changes are transferred from the server to the browser. The benefit of this approach is that the application performs extremely fast. When you click the details link to view details on a particular entry, the entry details appear instantly because all of the entries are stored on the client machine. When you perform key-up searches, by typing in the filter textbox, matching entries are displayed very quickly because the entries are being filtered on the local machine. This approach can have a dramatic effect on the performance of any interactive data-driven web application. Interacting with data on the client is almost always faster than interacting with the same data on the server. Retrieving Data from the Server In the JavaScript Reference application, I use Microsoft WCF Data Services to expose data to the browser. WCF Data Services generates a REST interface for your data automatically. Here are the steps: Create your database tables in Microsoft SQL Server. For example, I created a database named ReferenceDB and a database table named Entities. Use the Entity Framework to generate your data model. For example, I used the Entity Framework to generate a class named ReferenceDBEntities and a class named Entities. Expose your data through WCF Data Services. I added a WCF Data Service to my project and modified the data service class to look like this:   using System.Data.Services; using System.Data.Services.Common; using System.Web; using JavaScriptReference.Models; namespace JavaScriptReference.Services { [System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults = true)] public class EntryService : DataService<ReferenceDBEntities> { // This method is called only once to initialize service-wide policies. public static void InitializeService(DataServiceConfiguration config) { config.UseVerboseErrors = true; config.SetEntitySetAccessRule("*", EntitySetRights.All); config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; } // Define a change interceptor for the Products entity set. [ChangeInterceptor("Entries")] public void OnChangeEntries(Entry entry, UpdateOperations operations) { if (!HttpContext.Current.Request.IsAuthenticated) { throw new DataServiceException("Cannot update reference unless authenticated."); } } } }     The WCF data service is named EntryService. Notice that it derives from DataService<ReferenceEntitites>. Because it derives from DataService<ReferenceEntities>, the data service exposes the contents of the ReferenceEntitiesDB database. In the code above, I defined a ChangeInterceptor to prevent un-authenticated users from making changes to the database. Anyone can retrieve data through the service, but only authenticated users are allowed to make changes. After you expose data through a WCF Data Service, you can use jQuery to retrieve the data by performing an Ajax call. For example, I am using an Ajax call that looks something like this to retrieve the JavaScript entries from the EntryService.svc data service: $.ajax({ dataType: "json", url: “/Services/EntryService.svc/Entries”, success: function (result) { var data = callback(result["d"]); } });     Notice that you must unwrap the data using result[“d”]. After you unwrap the data, you have a JavaScript array of the entries. I’m transferring all 300+ entries from the server to the client when the application is opened for the first time. In other words, I transfer the entire database from the server to the client, once and only once, when the application is opened for the first time. The data is transferred using JSON. Here is a fragment: { "d" : [ { "__metadata": { "uri": "http://superexpert.com/javascriptreference/Services/EntryService.svc/Entries(1)", "type": "ReferenceDBModel.Entry" }, "Id": 1, "Name": "Global", "Browsers": "ff3_6,ie8,ie9,c8,sf5,es3,es5", "Syntax": "object", "ShortDescription": "Contains global variables and functions", "FullDescription": "<p>\nThe Global object is determined by the host environment. In web browsers, the Global object is the same as the windows object.\n</p>\n<p>\nYou can use the keyword <code>this</code> to refer to the Global object when in the global context (outside of any function).\n</p>\n<p>\nThe Global object holds all global variables and functions. For example, the following code demonstrates that the global <code>movieTitle</code> variable refers to the same thing as <code>window.movieTitle</code> and <code>this.movieTitle</code>.\n</p>\n<pre>\nvar movieTitle = \"Star Wars\";\nconsole.log(movieTitle === this.movieTitle); // true\nconsole.log(movieTitle === window.movieTitle); // true\n</pre>\n", "LastUpdated": "634298578273756641", "IsDeleted": false, "OwnerId": null }, { "__metadata": { "uri": "http://superexpert.com/javascriptreference/Services/EntryService.svc/Entries(2)", "type": "ReferenceDBModel.Entry" }, "Id": 2, "Name": "eval(string)", "Browsers": "ff3_6,ie8,ie9,c8,sf5,es3,es5", "Syntax": "function", "ShortDescription": "Evaluates and executes JavaScript code dynamically", "FullDescription": "<p>\nThe following code evaluates and executes the string \"3+5\" at runtime.\n</p>\n<pre>\nvar result = eval(\"3+5\");\nconsole.log(result); // returns 8\n</pre>\n<p>\nYou can rewrite the code above like this:\n</p>\n<pre>\nvar result;\neval(\"result = 3+5\");\nconsole.log(result);\n</pre>", "LastUpdated": "634298580913817644", "IsDeleted": false, "OwnerId": 1 } … ]} I worried about the amount of time that it would take to transfer the records. According to Google Chome, it takes about 5 seconds to retrieve all 300+ records on a broadband connection over the Internet. 5 seconds is a small price to pay to avoid performing any server fetches of the data in the future. And here are the estimated times using different types of connections using Fiddler: Notice that using a modem, it takes 33 seconds to download the database. 33 seconds is a significant chunk of time. So, I would not use the approach of transferring the entire database up front if you expect a significant portion of your website audience to connect to your website with a modem. Adding Data to HTML5 Local Storage After the JavaScript entries are retrieved from the server, the entries are stored in HTML5 local storage. Here’s the reference documentation for HTML5 storage for Internet Explorer: http://msdn.microsoft.com/en-us/library/cc197062(VS.85).aspx You access local storage by accessing the windows.localStorage object in JavaScript. This object contains key/value pairs. For example, you can use the following JavaScript code to add a new item to local storage: <script type="text/javascript"> window.localStorage.setItem("message", "Hello World!"); </script>   You can use the Google Chrome Storage tab in the Developer Tools (hit CTRL-SHIFT I in Chrome) to view items added to local storage: After you add an item to local storage, you can read it at any time in the future by using the window.localStorage.getItem() method: <script type="text/javascript"> window.localStorage.setItem("message", "Hello World!"); </script>   You only can add strings to local storage and not JavaScript objects such as arrays. Therefore, before adding a JavaScript object to local storage, you need to convert it into a JSON string. In the JavaScript Reference application, I use a wrapper around local storage that looks something like this: function Storage() { this.get = function (name) { return JSON.parse(window.localStorage.getItem(name)); }; this.set = function (name, value) { window.localStorage.setItem(name, JSON.stringify(value)); }; this.clear = function () { window.localStorage.clear(); }; }   If you use the wrapper above, then you can add arbitrary JavaScript objects to local storage like this: var store = new Storage(); // Add array to storage var products = [ {name:"Fish", price:2.33}, {name:"Bacon", price:1.33} ]; store.set("products", products); // Retrieve items from storage var products = store.get("products");   Modern browsers support the JSON object natively. If you need the script above to work with older browsers then you should download the JSON2.js library from: https://github.com/douglascrockford/JSON-js The JSON2 library will use the native JSON object if a browser already supports JSON. Merging Server Changes with Browser Local Storage When you first open the JavaScript Reference application, the entire database of JavaScript entries is transferred from the server to the browser. Two items are added to local storage: entries and entriesLastUpdated. The first item contains the entire entries database (a big JSON string of entries). The second item, a timestamp, represents the version of the entries. Whenever you open the JavaScript Reference in the future, the entriesLastUpdated timestamp is passed to the server. Only records that have been deleted, updated, or added since entriesLastUpdated are transferred to the browser. The OData query to get the latest updates looks like this: http://superexpert.com/javascriptreference/Services/EntryService.svc/Entries?$filter=(LastUpdated%20gt%20634301199890494792L) If you remove URL encoding, the query looks like this: http://superexpert.com/javascriptreference/Services/EntryService.svc/Entries?$filter=(LastUpdated gt 634301199890494792L) This query returns only those entries where the value of LastUpdated > 634301199890494792 (the version timestamp). The changes – new JavaScript entries, deleted entries, and updated entries – are merged with the existing entries in local storage. The JavaScript code for performing the merge is contained in the EntriesHelper.js file. The merge() method looks like this:   merge: function (oldEntries, newEntries) { // concat (this performs the add) oldEntries = oldEntries || []; var mergedEntries = oldEntries.concat(newEntries); // sort this.sortByIdThenLastUpdated(mergedEntries); // prune duplicates (this performs the update) mergedEntries = this.pruneDuplicates(mergedEntries); // delete mergedEntries = this.removeIsDeleted(mergedEntries); // Sort this.sortByName(mergedEntries); return mergedEntries; },   The contents of local storage are then updated with the merged entries. I spent several hours writing the merge() method (much longer than I expected). I found two resources to be extremely useful. First, I wrote extensive unit tests for the merge() method. I wrote the unit tests using server-side JavaScript. I describe this approach to writing unit tests in this blog entry. The unit tests are included in the JavaScript Reference source code. Second, I found the following blog entry to be super useful (thanks Nick!): http://nicksnettravels.builttoroam.com/post/2010/08/03/OData-Synchronization-with-WCF-Data-Services.aspx One big challenge that I encountered involved timestamps. I originally tried to store an actual UTC time as the value of the entriesLastUpdated item. I quickly discovered that trying to work with dates in JSON turned out to be a big can of worms that I did not want to open. Next, I tried to use a SQL timestamp column. However, I learned that OData cannot handle the timestamp data type when doing a filter query. Therefore, I ended up using a bigint column in SQL and manually creating the value when a record is updated. I overrode the SaveChanges() method to look something like this: public override int SaveChanges(SaveOptions options) { var changes = this.ObjectStateManager.GetObjectStateEntries( EntityState.Modified | EntityState.Added | EntityState.Deleted); foreach (var change in changes) { var entity = change.Entity as IEntityTracking; if (entity != null) { entity.LastUpdated = DateTime.Now.Ticks; } } return base.SaveChanges(options); }   Notice that I assign Date.Now.Ticks to the entity.LastUpdated property whenever an entry is modified, added, or deleted. Summary After building the JavaScript Reference application, I am convinced that HTML5 local storage can have a dramatic impact on the performance of any data-driven web application. If you are building a web application that involves extensive interaction with data then I recommend that you take advantage of this new feature included in the HTML5 standard.

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  • The entity type String is not part of the model for the current context error [migrated]

    - by Michael V
    I am getting the following error in my controller after the view submits the collection: The entity type String is not part of the model for the current context. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidOperationException: The entity type String is not part of the model for the current context. Source Error: Line 51: foreach (var survey in mysurveys) Line 52: { Line 53: db.Entry(survey).State = EntityState.Modified; Line 54: Line 55: // db.Entry(survey).State = EntityState.Modified; Here is the code ` [HttpPost] public ActionResult UpdateTest(FormCollection mysurveys) { System.Diagnostics.Debug.WriteLine("iam in test post" + mysurveys.Count); foreach (var survey in mysurveys) { db.Entry(survey).State = EntityState.Modified; } db.SaveChanges(); return View(mysurveys); } `Similar code with one record only (no foreach) works fine

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  • NoSQL with RavenDB and ASP.NET MVC - Part 2

    - by shiju
    In my previous post, we have discussed on how to work with RavenDB document database in an ASP.NET MVC application. We have setup RavenDB for our ASP.NET MVC application and did basic CRUD operations against a simple domain entity. In this post, let’s discuss on domain entity with deep object graph and how to query against RavenDB documents using Indexes.Let's create two domain entities for our demo ASP.NET MVC appplication  public class Category {       public string Id { 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 List<Expense> Expenses { get; set; }       public Category()     {         Expenses = new List<Expense>();     } }    public class Expense {       public string Id { get; set; }     public Category Category { get; set; }     public string  Transaction { get; set; }     public DateTime Date { get; set; }     public double Amount { get; set; }   }  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.Let's create  ASP.NET MVC view model  for Expense transaction public class ExpenseViewModel {     public string Id { get; set; }       public string CategoryId { get; set; }       [Required(ErrorMessage = "Transaction Required")]            public string Transaction { get; set; }       [Required(ErrorMessage = "Date Required")]            public DateTime Date { get; set; }       [Required(ErrorMessage = "Amount Required")]     public double Amount { get; set; }       public IEnumerable<SelectListItem> Category { get; set; } } Let's create a contract type for Expense Repository  public interface IExpenseRepository {     Expense Load(string id);     IEnumerable<Expense> GetExpenseTransactions(DateTime startDate,DateTime endDate);     void Save(Expense expense,string categoryId);     void Delete(string id);  } Let's create a concrete type for Expense Repository for handling CRUD operations. public class ExpenseRepository : IExpenseRepository {   private IDocumentSession session; public ExpenseRepository() {         session = MvcApplication.CurrentSession; } public Expense Load(string id) {     return session.Load<Expense>(id); } public IEnumerable<Expense> GetExpenseTransactions(DateTime startDate, DateTime endDate) {             //Querying using the Index name "ExpenseTransactions"     //filtering with dates     var expenses = session.LuceneQuery<Expense>("ExpenseTransactions")         .WaitForNonStaleResults()         .Where(exp => exp.Date >= startDate && exp.Date <= endDate)         .ToArray();     return expenses; } public void Save(Expense expense,string categoryId) {     var category = session.Load<Category>(categoryId);     if (string.IsNullOrEmpty(expense.Id))     {         //new expense transaction         expense.Category = category;         session.Store(expense);     }     else     {         //modifying an existing expense transaction         var expenseToEdit = Load(expense.Id);         //Copy values to  expenseToEdit         ModelCopier.CopyModel(expense, expenseToEdit);         //set category object         expenseToEdit.Category = category;       }     //save changes     session.SaveChanges(); } public void Delete(string id) {     var expense = Load(id);     session.Delete<Expense>(expense);     session.SaveChanges(); }   }  Insert/Update Expense Transaction The Save method is used for both insert a new expense record and modifying an existing expense transaction. For a new expense transaction, we store the expense object with associated category into document session object and load the existing expense object and assign values to it for editing a existing record.  public void Save(Expense expense,string categoryId) {     var category = session.Load<Category>(categoryId);     if (string.IsNullOrEmpty(expense.Id))     {         //new expense transaction         expense.Category = category;         session.Store(expense);     }     else     {         //modifying an existing expense transaction         var expenseToEdit = Load(expense.Id);         //Copy values to  expenseToEdit         ModelCopier.CopyModel(expense, expenseToEdit);         //set category object         expenseToEdit.Category = category;       }     //save changes     session.SaveChanges(); } Querying Expense transactions   public IEnumerable<Expense> GetExpenseTransactions(DateTime startDate, DateTime endDate) {             //Querying using the Index name "ExpenseTransactions"     //filtering with dates     var expenses = session.LuceneQuery<Expense>("ExpenseTransactions")         .WaitForNonStaleResults()         .Where(exp => exp.Date >= startDate && exp.Date <= endDate)         .ToArray();     return expenses; }  The GetExpenseTransactions method returns expense transactions using a LINQ query expression with a Date comparison filter. The Lucene Query is using a index named "ExpenseTransactions" for getting the result set. In RavenDB, Indexes are LINQ queries stored in the RavenDB server and would be  executed on the background and will perform query against the JSON documents. Indexes will be working with a lucene query expression or a set operation. Indexes are composed using a Map and Reduce function. Check out Ayende's blog post on Map/Reduce We can create index using RavenDB web admin tool as well as programmitically using its Client API. The below shows the screen shot of creating index using web admin tool. We can also create Indexes using Raven Cleint API as shown in the following code documentStore.DatabaseCommands.PutIndex("ExpenseTransactions",     new IndexDefinition<Expense,Expense>() {     Map = Expenses => from exp in Expenses                     select new { exp.Date } });  In the Map function, we used a Linq expression as shown in the following from exp in docs.Expensesselect new { exp.Date };We have not used a Reduce function for the above index. A Reduce function is useful while performing aggregate functions based on the results from the Map function. Indexes can be use with set operations of RavenDB.SET OperationsUnlike other document databases, RavenDB supports set based operations that lets you to perform updates, deletes and inserts to the bulk_docs endpoint of RavenDB. For doing this, you just pass a query to a Index as shown in the following commandDELETE http://localhost:8080/bulk_docs/ExpenseTransactions?query=Date:20100531The above command using the Index named "ExpenseTransactions" for querying the documents with Date filter and  will delete all the documents that match the query criteria. The above command is equivalent of the following queryDELETE FROM ExpensesWHERE Date='2010-05-31' Controller & ActionsWe have created Expense Repository class for performing CRUD operations for the Expense transactions. Let's create a controller class for handling expense transactions.   public class ExpenseController : Controller { private ICategoryRepository categoyRepository; private IExpenseRepository expenseRepository; public ExpenseController(ICategoryRepository categoyRepository, IExpenseRepository expenseRepository) {     this.categoyRepository = categoyRepository;     this.expenseRepository = expenseRepository; } //Get Expense transactions based on dates public ActionResult Index(DateTime? StartDate, DateTime? EndDate) {     //If date is not passed, take current month's first and last dte     DateTime dtNow;     dtNow = DateTime.Today;     if (!StartDate.HasValue)     {         StartDate = new DateTime(dtNow.Year, dtNow.Month, 1);         EndDate = StartDate.Value.AddMonths(1).AddDays(-1);     }     //take last date of startdate's month, if endate is not passed     if (StartDate.HasValue && !EndDate.HasValue)     {         EndDate = (new DateTime(StartDate.Value.Year, StartDate.Value.Month, 1)).AddMonths(1).AddDays(-1);     }       var expenses = expenseRepository.GetExpenseTransactions(StartDate.Value, EndDate.Value);     if (Request.IsAjaxRequest())     {           return PartialView("ExpenseList", expenses);     }     ViewData.Add("StartDate", StartDate.Value.ToShortDateString());     ViewData.Add("EndDate", EndDate.Value.ToShortDateString());             return View(expenses);            }   // GET: /Expense/Edit public ActionResult Edit(string id) {       var expenseModel = new ExpenseViewModel();     var expense = expenseRepository.Load(id);     ModelCopier.CopyModel(expense, expenseModel);     var categories = categoyRepository.GetCategories();     expenseModel.Category = categories.ToSelectListItems(expense.Category.Id.ToString());                    return View("Save", expenseModel);          }   // // GET: /Expense/Create   public ActionResult Create() {     var expenseModel = new ExpenseViewModel();               var categories = categoyRepository.GetCategories();     expenseModel.Category = categories.ToSelectListItems("-1");     expenseModel.Date = DateTime.Today;     return View("Save", expenseModel); }   // // POST: /Expense/Save // Insert/Update Expense Tansaction [HttpPost] public ActionResult Save(ExpenseViewModel expenseViewModel) {     try     {         if (!ModelState.IsValid)         {               var categories = categoyRepository.GetCategories();                 expenseViewModel.Category = categories.ToSelectListItems(expenseViewModel.CategoryId);                               return View("Save", expenseViewModel);         }           var expense=new Expense();         ModelCopier.CopyModel(expenseViewModel, expense);          expenseRepository.Save(expense, expenseViewModel.CategoryId);                       return RedirectToAction("Index");     }     catch     {         return View();     } } //Delete a Expense Transaction public ActionResult Delete(string id) {     expenseRepository.Delete(id);     return RedirectToAction("Index");     }     }     Download the Source - You can download the source code from http://ravenmvc.codeplex.com

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  • Azure Table Storage Creation using Nov 2009 CTP

    - by kaleidoscope
    The new SDK introduces a new class - · The CloudTableClient : This new class enables us to create tables and test for the existence of tables. We need not need use this class for querying table storage, it's   more of an administrative class for dealing with table storage itself.   · Once we have got the account key and the account name from ConfigurationSetting, we can create an instance of the storage credentials and table client classes:   StorageCredentialsAccountAndKey creds = new StorageCredentialsAccountAndKey(accountName, accountKey);     CloudTableClient tableStorage = new CloudTableClient(tableBaseUri, creds);     CustomerContext ctx = new CustomerContext(tableBaseUri, creds);     //where tableBaseUri is the TableStorageEndpoint obtained from ConfigurationSetting Using the table storage class, we can now create a new table (if it doesn't already exist):     if (tableStorage.CreateTableIfNotExist("Customers"))     {        CustomerRow cust = new CustomerRow("AccountsReceivable", "kevin");         cust.FirstName = "Kevin";        cust.LastName = "Hoffman";        ctx.AddObject("Customers", cust);        ctx.SaveChanges();     } For a complete article on this topic please follow this link: http://dotnetaddict.dotnetdevelopersjournal.com/azure_nov09_tablestorage.htm Tinu, O

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  • Update primary key value using entity framework

    - by lemkepf
    I'm trying to update one value of a compound primary key from within the entity framework and I'm getting this error: "The property 'CustomerID' is part of the object's key information and cannot be modified. " Here is my code: Dim customer As Customer = (From c In db.Customer Where c.CustomerID = "xxx" AndAlso c.SiteKey = siteKey).FirstOrDefault customer.CustomerID = "fasdfasdf" db.SaveChanges() It seems too simple. Is it true you can't update a primary key within the entity framework? I can't find any documentation on the topic. Thanks!

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  • MVC 2 Entity Framework View Model Insert

    - by cannibalcorpse
    This is driving me crazy. Hopefully my question makes sense... I'm using MVC 2 and Entity Framework 1 and am trying to insert a new record with two navigation properties. I have a SQL table, Categories, that has a lookup table CategoryTypes and another self-referencing lookup CategoryParent. EF makes two nav properties on my Category model, one called Parent and another called CategoryType, both instances of their respective models. On my view that creates the new Category, I have two dropdowns, one for the CategoryType and another for the ParentCategory. When I try and insert the new Category WITHOUT the ParentCategory, which allows nulls, everything is fine. As soon as I add the ParentCategory, the insert fails, and oddly (or so I think) complains about the CategoryType in the form of this error: 0 related 'CategoryTypes' were found. 1 'CategoryTypes' is expected. When I step through, I can verifiy that both ID properties coming in on the action method parameter are correct. I can also verify that when I go to the db to get the CategoryType and ParentCategory with the ID's, the records are being pulled fine. Yet it fails on SaveChanges(). All that I can see is that my CategoryParent dropdownlistfor in my view, is somehow causing the insert to bomb. Please see my comments in my httpPost Create action method. My view model looks like this: public class EditModel { public Category MainCategory { get; set; } public IEnumerable<CategoryType> CategoryTypesList { get; set; } public IEnumerable<Category> ParentCategoriesList { get; set; } } My Create action methods look like this: // GET: /Categories/Create public ActionResult Create() { return View(new EditModel() { CategoryTypesList = _db.CategoryTypeSet.ToList(), ParentCategoriesList = _db.CategorySet.ToList() }); } // POST: /Categories/Create [HttpPost] public ActionResult Create(Category mainCategory) { if (!ModelState.IsValid) return View(new EditModel() { MainCategory = mainCategory, CategoryTypesList = _db.CategoryTypeSet.ToList(), ParentCategoriesList = _db.CategorySet.ToList() }); mainCategory.CategoryType = _db.CategoryTypeSet.First(ct => ct.Id == mainCategory.CategoryType.Id); // This db call DOES get the correct Category, but fails on _db.SaveChanges(). // Oddly the error is related to CategoryTypes and not Category. // Entities in 'DbEntities.CategorySet' participate in the 'FK_Categories_CategoryTypes' relationship. // 0 related 'CategoryTypes' were found. 1 'CategoryTypes' is expected. //mainCategory.Parent = _db.CategorySet.First(c => c.Id == mainCategory.Parent.Id); // If I just use the literal ID of the same Category, // AND comment out the CategoryParent dropdownlistfor in the view, all is fine. mainCategory.Parent = _db.CategorySet.First(c => c.Id == 2); _db.AddToCategorySet(mainCategory); _db.SaveChanges(); return RedirectToAction("Index"); } Here is my Create form on the view : <% using (Html.BeginForm()) {%> <%= Html.ValidationSummary(true) %> <fieldset> <legend>Fields</legend> <div> <%= Html.LabelFor(model => model.MainCategory.Parent.Id) %> <%= Html.DropDownListFor(model => model.MainCategory.Parent.Id, new SelectList(Model.ParentCategoriesList, "Id", "Name")) %> <%= Html.ValidationMessageFor(model => model.MainCategory.Parent.Id) %> </div> <div> <%= Html.LabelFor(model => model.MainCategory.CategoryType.Id) %> <%= Html.DropDownListFor(model => model.MainCategory.CategoryType.Id, new SelectList(Model.CategoryTypesList, "Id", "Name"))%> <%= Html.ValidationMessageFor(model => model.MainCategory.CategoryType.Id)%> </div> <div> <%= Html.LabelFor(model => model.MainCategory.Name) %> <%= Html.TextBoxFor(model => model.MainCategory.Name)%> <%= Html.ValidationMessageFor(model => model.MainCategory.Name)%> </div> <div> <%= Html.LabelFor(model => model.MainCategory.Description)%> <%= Html.TextAreaFor(model => model.MainCategory.Description)%> <%= Html.ValidationMessageFor(model => model.MainCategory.Description)%> </div> <div> <%= Html.LabelFor(model => model.MainCategory.SeoName)%> <%= Html.TextBoxFor(model => model.MainCategory.SeoName, new { @class = "large" })%> <%= Html.ValidationMessageFor(model => model.MainCategory.SeoName)%> </div> <div> <%= Html.LabelFor(model => model.MainCategory.HasHomepage)%> <%= Html.CheckBoxFor(model => model.MainCategory.HasHomepage)%> <%= Html.ValidationMessageFor(model => model.MainCategory.HasHomepage)%> </div> <p><input type="submit" value="Create" /></p> </fieldset> <% } %> Maybe I've just been staying up too late playing with MVC 2? :) Please let me know if I'm not being clear enough.

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  • insert,update, delete derived entity in entity framework 4.0

    - by user282807
    Hi! How do i insert an entity that is derived from another entity. here is my code but it's not working:(applicationreplacement derived from application Blockquote ObjectContect _ctx public void AddReplacementApp(Application entity,ApplicationReplacement rentity) { _ctx.CreateObjectSet<Application>(rentity); _ctx.SaveChanges(); } Blockquote

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  • How to add entity object to adequate entity set with object context in EF?

    - by Levelbit
    I have a problem when I add an entity object with ObjectContext.AddObject method because I can't retrieve that object with LINQ querying my ObjectContext.Person entities. I know that this new added object is stored somewhere, because it is used to update database after SaveChanges method. That's bothers me because I want to update my datagrid DataContext without saving changes unless I really want to do it. It doesn't help if I add the same object to DataContext list myself directly.

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  • Updating with Related Entities - Entity Framework v4

    - by Vincent BOUZON
    Hi, I use Entity Framework V4 and i want to update Customer who have Visits. My code : EntityKey key; object originalItem; key = this._modelContainer.CreateEntityKey("Customers", customer); if (this._modelContainer.TryGetObjectByKey(key, out originalItem)) { this._modelContainer.ApplyCurrentValues(key.EntitySetName, customer); } this._modelContainer.SaveChanges(); It works for Scalar Property only. The customers.Visits collection is not updated. Best Regards :)

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  • Advantage of creating a generic repository vs. specific repository for each object?

    - by LuckyLindy
    We are developing an ASP.NET MVC application, and are now building the repository/service classes. I'm wondering if there are any major advantages to creating a generic IRepository interface that all repositories implement, vs. each Repository having its own unique interface and set of methods. For example: a generic IRepository interface might look like (taken from this answer): public interface IRepository : IDisposable { T[] GetAll<T>(); T[] GetAll<T>(Expression<Func<T, bool>> filter); T GetSingle<T>(Expression<Func<T, bool>> filter); T GetSingle<T>(Expression<Func<T, bool>> filter, List<Expression<Func<T, object>>> subSelectors); void Delete<T>(T entity); void Add<T>(T entity); int SaveChanges(); DbTransaction BeginTransaction(); } Each Repository would implement this interface (e.g. CustomerRepository:IRepository, ProductRepository:IRepository, etc). The alternate that we've followed in prior projects would be: public interface IInvoiceRepository : IDisposable { EntityCollection<InvoiceEntity> GetAllInvoices(int accountId); EntityCollection<InvoiceEntity> GetAllInvoices(DateTime theDate); InvoiceEntity GetSingleInvoice(int id, bool doFetchRelated); InvoiceEntity GetSingleInvoice(DateTime invoiceDate, int accountId); //unique InvoiceEntity CreateInvoice(); InvoiceLineEntity CreateInvoiceLine(); void SaveChanges(InvoiceEntity); //handles inserts or updates void DeleteInvoice(InvoiceEntity); void DeleteInvoiceLine(InvoiceLineEntity); } In the second case, the expressions (LINQ or otherwise) would be entirely contained in the Repository implementation, whoever is implementing the service just needs to know which repository function to call. I guess I don't see the advantage of writing all the expression syntax in the service class and passing to the repository. Wouldn't this mean easy-to-messup LINQ code is being duplicated in many cases? For example, in our old invoicing system, we call InvoiceRepository.GetSingleInvoice(DateTime invoiceDate, int accountId) from a few different services (Customer, Invoice, Account, etc). That seems much cleaner than writing the following in multiple places: rep.GetSingle(x => x.AccountId = someId && x.InvoiceDate = someDate.Date); The only disadvantage I see to using the specific approach is that we could end up with many permutations of Get* functions, but this still seems preferable to pushing the expression logic up into the Service classes. What am I missing?

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  • Issues with LINQ (to Entity) [adding records]

    - by Mario
    I am using LINQ to Entity in a project, where I pull a bunch of data (from the database) and organize it into a bunch of objects and save those to the database. I have not had problems writing to the db before using LINQ to Entity, but I have run into a snag with this particular one. Here's the error I get (this is the "InnerException", the exception itself is useless!): New transaction is not allowed because there are other threads running in the session. I have seen that before, when I was trying to save my changes inside a loop. In this case, the loop finishes, and it tries to make that call, only to give me the exception. Here's the current code: try { //finalResult is a list of the keys to match on for the records being pulled foreach (int i in finalResult) { var queryEff = (from eff in dbMRI.MemberEligibility where eff.Member_Key == i && eff.EffDate >= DateTime.Now select eff.EffDate).Min(); if (queryEff != null) { //Add a record to the Process table Process prRecord = new Process(); prRecord.GroupData = qa; prRecord.Member_Key = i; prRecord.ProcessDate = DateTime.Now; prRecord.RecordType = "F"; prRecord.UsernameMarkedBy = "Autocard"; prRecord.GroupsId = qa.GroupsID; prRecord.Quantity = 2; prRecord.EffectiveDate = queryEff; dbMRI.AddObject("Process", prRecord); } } dbMRI.SaveChanges(); //<-- Crashes here foreach (int i in finalResult) { var queryProc = from pro in dbMRI.Process where pro.Member_Key == i && pro.UsernameMarkedBy == "Autocard" select pro; foreach (var qp in queryProc) { Audit aud = new Audit(); aud.Member_Key = i; aud.ProcessId = qp.ProcessId; aud.MarkDate = DateTime.Now; aud.MarkedByUsername = "Autocard"; aud.GroupData = qa; dbMRI.AddObject("Audit", aud); } } dbMRI.SaveChanges(); //<-- AND here (if the first one is commented out) } catch (Exception e) { //Do Something here } Basically, I need it to insert a record, get the identity for that inserted record and insert a record into another table with the identity from the first record. Given some other constraints, it is not possible to create a FK relationship between the two (I've tried, but some other parts of the app won't allow it, AND my DBA team for whatever reason hates FK's, but that's for a different topic :)) Any ideas what might be causing this? Thank!

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  • Row insertion order entity framework

    - by Wouter
    I'm using a transaction to insert multiple rows in multiple tables. For these rows I would like to add these rows in order. Upon calling SaveChanges all the rows are inserted out of order. When not using a transaction and saving changes after each insertion does keep order, but I really need a transaction for all entries.

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  • Entity framework 4 add to many-to-many

    - by mehanik
    I have model whith 3 tabels and one is link table with additional field: Groups Id Name Users Id Name Roles Id Name LinkTable Id GroupId UserId RoleId The quuestion is how to add 3 related entities: Code bellow doesn't work. using (var db = new dbEntities()) { db.Groups.AddObject(Group.CreateGroup(1, "TestGroup")); db.Users.AddObject(User.CreateUser(1, "AdminUser")); db.Roles.AddObject(Role.CreateRole(1, "Admin")); db.UserGroupRoles.AddObject(UserGroupRole.CreateUserGroupRole(1, 1, 1, 1)); db.SaveChanges(); }

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