Search Results

Search found 720 results on 29 pages for 'tolist'.

Page 10/29 | < Previous Page | 6 7 8 9 10 11 12 13 14 15 16 17  | Next Page >

  • C#/.NET Little Wonders: The Predicate, Comparison, and Converter Generic Delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last three weeks, we examined the Action family of delegates (and delegates in general), the Func family of delegates, and the EventHandler family of delegates and how they can be used to support generic, reusable algorithms and classes. This week I will be completing my series on the generic delegates in the .NET Framework with a discussion of three more, somewhat less used, generic delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>. These are older generic delegates that were introduced in .NET 2.0, mostly for use in the Array and List<T> classes.  Though older, it’s good to have an understanding of them and their intended purpose.  In addition, you can feel free to use them yourself, though obviously you can also use the equivalents from the Func family of delegates instead. Predicate<T> – delegate for determining matches The Predicate<T> delegate was a very early delegate developed in the .NET 2.0 Framework to determine if an item was a match for some condition in a List<T> or T[].  The methods that tend to use the Predicate<T> include: Find(), FindAll(), FindLast() Uses the Predicate<T> delegate to finds items, in a list/array of type T, that matches the given predicate. FindIndex(), FindLastIndex() Uses the Predicate<T> delegate to find the index of an item, of in a list/array of type T, that matches the given predicate. The signature of the Predicate<T> delegate (ignoring variance for the moment) is: 1: public delegate bool Predicate<T>(T obj); So, this is a delegate type that supports any method taking an item of type T and returning bool.  In addition, there is a semantic understanding that this predicate is supposed to be examining the item supplied to see if it matches a given criteria. 1: // finds first even number (2) 2: var firstEven = Array.Find(numbers, n => (n % 2) == 0); 3:  4: // finds all odd numbers (1, 3, 5, 7, 9) 5: var allEvens = Array.FindAll(numbers, n => (n % 2) == 1); 6:  7: // find index of first multiple of 5 (4) 8: var firstFiveMultiplePos = Array.FindIndex(numbers, n => (n % 5) == 0); This delegate has typically been succeeded in LINQ by the more general Func family, so that Predicate<T> and Func<T, bool> are logically identical.  Strictly speaking, though, they are different types, so a delegate reference of type Predicate<T> cannot be directly assigned to a delegate reference of type Func<T, bool>, though the same method can be assigned to both. 1: // SUCCESS: the same lambda can be assigned to either 2: Predicate<DateTime> isSameDayPred = dt => dt.Date == DateTime.Today; 3: Func<DateTime, bool> isSameDayFunc = dt => dt.Date == DateTime.Today; 4:  5: // ERROR: once they are assigned to a delegate type, they are strongly 6: // typed and cannot be directly assigned to other delegate types. 7: isSameDayPred = isSameDayFunc; When you assign a method to a delegate, all that is required is that the signature matches.  This is why the same method can be assigned to either delegate type since their signatures are the same.  However, once the method has been assigned to a delegate type, it is now a strongly-typed reference to that delegate type, and it cannot be assigned to a different delegate type (beyond the bounds of variance depending on Framework version, of course). Comparison<T> – delegate for determining order Just as the Predicate<T> generic delegate was birthed to give Array and List<T> the ability to perform type-safe matching, the Comparison<T> was birthed to give them the ability to perform type-safe ordering. The Comparison<T> is used in Array and List<T> for: Sort() A form of the Sort() method that takes a comparison delegate; this is an alternate way to custom sort a list/array from having to define custom IComparer<T> classes. The signature for the Comparison<T> delegate looks like (without variance): 1: public delegate int Comparison<T>(T lhs, T rhs); The goal of this delegate is to compare the left-hand-side to the right-hand-side and return a negative number if the lhs < rhs, zero if they are equal, and a positive number if the lhs > rhs.  Generally speaking, null is considered to be the smallest value of any reference type, so null should always be less than non-null, and two null values should be considered equal. In most sort/ordering methods, you must specify an IComparer<T> if you want to do custom sorting/ordering.  The Array and List<T> types, however, also allow for an alternative Comparison<T> delegate to be used instead, essentially, this lets you perform the custom sort without having to have the custom IComparer<T> class defined. It should be noted, however, that the LINQ OrderBy(), and ThenBy() family of methods do not support the Comparison<T> delegate (though one could easily add their own extension methods to create one, or create an IComparer() factory class that generates one from a Comparison<T>). So, given this delegate, we could use it to perform easy sorts on an Array or List<T> based on custom fields.  Say for example we have a data class called Employee with some basic employee information: 1: public sealed class Employee 2: { 3: public string Name { get; set; } 4: public int Id { get; set; } 5: public double Salary { get; set; } 6: } And say we had a List<Employee> that contained data, such as: 1: var employees = new List<Employee> 2: { 3: new Employee { Name = "John Smith", Id = 2, Salary = 37000.0 }, 4: new Employee { Name = "Jane Doe", Id = 1, Salary = 57000.0 }, 5: new Employee { Name = "John Doe", Id = 5, Salary = 60000.0 }, 6: new Employee { Name = "Jane Smith", Id = 3, Salary = 59000.0 } 7: }; Now, using the Comparison<T> delegate form of Sort() on the List<Employee>, we can sort our list many ways: 1: // sort based on employee ID 2: employees.Sort((lhs, rhs) => Comparer<int>.Default.Compare(lhs.Id, rhs.Id)); 3:  4: // sort based on employee name 5: employees.Sort((lhs, rhs) => string.Compare(lhs.Name, rhs.Name)); 6:  7: // sort based on salary, descending (note switched lhs/rhs order for descending) 8: employees.Sort((lhs, rhs) => Comparer<double>.Default.Compare(rhs.Salary, lhs.Salary)); So again, you could use this older delegate, which has a lot of logical meaning to it’s name, or use a generic delegate such as Func<T, T, int> to implement the same sort of behavior.  All this said, one of the reasons, in my opinion, that Comparison<T> isn’t used too often is that it tends to need complex lambdas, and the LINQ ability to order based on projections is much easier to use, though the Array and List<T> sorts tend to be more efficient if you want to perform in-place ordering. Converter<TInput, TOutput> – delegate to convert elements The Converter<TInput, TOutput> delegate is used by the Array and List<T> delegate to specify how to convert elements from an array/list of one type (TInput) to another type (TOutput).  It is used in an array/list for: ConvertAll() Converts all elements from a List<TInput> / TInput[] to a new List<TOutput> / TOutput[]. The delegate signature for Converter<TInput, TOutput> is very straightforward (ignoring variance): 1: public delegate TOutput Converter<TInput, TOutput>(TInput input); So, this delegate’s job is to taken an input item (of type TInput) and convert it to a return result (of type TOutput).  Again, this is logically equivalent to a newer Func delegate with a signature of Func<TInput, TOutput>.  In fact, the latter is how the LINQ conversion methods are defined. So, we could use the ConvertAll() syntax to convert a List<T> or T[] to different types, such as: 1: // get a list of just employee IDs 2: var empIds = employees.ConvertAll(emp => emp.Id); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.ConvertAll(emp => (int)emp.Salary); Note that the expressions above are logically equivalent to using LINQ’s Select() method, which gives you a lot more power: 1: // get a list of just employee IDs 2: var empIds = employees.Select(emp => emp.Id).ToList(); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.Select(emp => (int)emp.Salary).ToList(); The only difference with using LINQ is that many of the methods (including Select()) are deferred execution, which means that often times they will not perform the conversion for an item until it is requested.  This has both pros and cons in that you gain the benefit of not performing work until it is actually needed, but on the flip side if you want the results now, there is overhead in the behind-the-scenes work that support deferred execution (it’s supported by the yield return / yield break keywords in C# which define iterators that maintain current state information). In general, the new LINQ syntax is preferred, but the older Array and List<T> ConvertAll() methods are still around, as is the Converter<TInput, TOutput> delegate. Sidebar: Variance support update in .NET 4.0 Just like our descriptions of Func and Action, these three early generic delegates also support more variance in assignment as of .NET 4.0.  Their new signatures are: 1: // comparison is contravariant on type being compared 2: public delegate int Comparison<in T>(T lhs, T rhs); 3:  4: // converter is contravariant on input and covariant on output 5: public delegate TOutput Contravariant<in TInput, out TOutput>(TInput input); 6:  7: // predicate is contravariant on input 8: public delegate bool Predicate<in T>(T obj); Thus these delegates can now be assigned to delegates allowing for contravariance (going to a more derived type) or covariance (going to a less derived type) based on whether the parameters are input or output, respectively. Summary Today, we wrapped up our generic delegates discussion by looking at three lesser-used delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>.  All three of these tend to be replaced by their more generic Func equivalents in LINQ, but that doesn’t mean you shouldn’t understand what they do or can’t use them for your own code, as they do contain semantic meanings in their names that sometimes get lost in the more generic Func name.   Tweet Technorati Tags: C#,CSharp,.NET,Little Wonders,delegates,generics,Predicate,Converter,Comparison

    Read the article

  • Find The Bug

    - by Alois Kraus
    What does this code print and why?             HashSet<int> set = new HashSet<int>();             int[] data = new int[] { 1, 2, 1, 2 };             var unique = from i in data                          where set.Add(i)                          select i;   // Compiles to: var unique = Enumerable.Where(data, (i) => set.Add(i));             foreach (var i in unique)             {                 Console.WriteLine("First: {0}", i);             }               foreach (var i in unique)             {                 Console.WriteLine("Second: {0}", i);             }   The output is: First: 1 First: 2 Why is there no output of the second loop? The reason is that LINQ does not cache the results of the collection but it does recalculate the contents for every new enumeration again. Since I have used state (the Hashset does decide which entries are part of the output) I do arrive with an empty sequence since Add of the Hashset will return false for all values I have already passed in leaving nothing to return a second time. The solution is quite simple: Use the Distinct extension method or cache the results by calling .ToList() or ToArray() for the result of the LINQ query. Lession Learned: Do never forget to think about state in Where clauses!

    Read the article

  • Getting codebaseHQ SVN ChangeLog data in your application

    - by saifkhan
    I deploy apps via ClickOnce. After each deployment we have to review the changes made and send out an email to the users with the changes. What I decided now to do is to use CodebaseHQ’s API to access a project’s SVN repository and display the commit notes so some users who download new updates can check what was changed or updated in an app. This saves a heck of a lot of time, especially when your apps are in beta and you are making several changes daily based on feedback. You can read up on their API here Here is a sample on how to access the Repositories API from a windows app Public Sub GetLog() If String.IsNullOrEmpty(_url) Then Exit Sub Dim answer As String = String.Empty Dim myReq As HttpWebRequest = WebRequest.Create(_url) With myReq .Headers.Add("Authorization", String.Format("Basic {0}", Convert.ToBase64String(Encoding.ASCII.GetBytes("username:password")))) .ContentType = "application/xml" .Accept = "application/xml" .Method = "POST" End With Try Using response As HttpWebResponse = myReq.GetResponse() Using sr As New System.IO.StreamReader(response.GetResponseStream()) answer = sr.ReadToEnd() Dim doc As XDocument = XDocument.Parse(answer) Dim commits = From commit In doc.Descendants("commit") _ Select Message = commit.Element("message").Value, _ AuthorName = commit.Element("author-name").Value, _ AuthoredDate = DateTime.Parse(commit.Element("authored-at").Value).Date grdLogData.BeginUpdate() grdLogData.DataSource = commits.ToList() grdLogData.EndUpdate() End Using End Using Catch ex As Exception MsgBox(ex.Message) End Try End Sub

    Read the article

  • Simplify Your Code with LINQ

    - by dwahlin
    I’m a big fan of LINQ and use it wherever I can to minimize code and make applications easier to maintain overall. I was going through a code file today refactoring it based on suggestions provided by Resharper and came across the following method: private List<string> FilterTokens(List<string> tokens) { var cleanedTokens = new List<string>(); for (int i = 0; i < tokens.Count; i++) { string token = tokens[i]; if (token != null) { cleanedTokens.Add(token); } } return cleanedTokens; }   In looking through the code I didn’t see anything wrong but Resharper was suggesting that I convert it to a LINQ expression: In thinking about it more the suggestion made complete sense because I simply wanted to add all non-null token values into a List<string> anyway. After following through with the Resharper suggestion the code changed to the following. Much, much cleaner and yet another example of why LINQ (and Resharper) rules: private List<string> FilterTokens(IEnumerable<string> tokens) { return tokens.Where(token => token != null).ToList(); }

    Read the article

  • Using OData to get Mix10 files

    - by Jon Dalberg
    There has been a lot of talk around OData lately (go to odata.org for more information) and I wanted to get all the videos from Mix ‘10: two great tastes that taste great together. Luckily, Mix has exposed the ‘10 sessions via OData at http://api.visitmix.com/OData.svc, now all I have to do is slap together a bit of code to fetch the videos. Step 1 (cut a hole in the box) Create a new console application and add a new service reference. Step 2 (put your junk in the box) Write a smidgen of code: 1: static void Main(string[] args) 2: { 3: var mix = new Mix.EventEntities(new Uri("http://api.visitmix.com/OData.svc")); 4:   5: var files = from f in mix.Files 6: where f.TypeName == "WMV" 7: select f; 8:   9: var web = new WebClient(); 10: 11: var myVideos = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyVideos), "Mix10"); 12:   13: Directory.CreateDirectory(myVideos); 14:   15: files.ToList().ForEach(f => { 16: var fileName = new Uri(f.Url).Segments.Last(); 17: Console.WriteLine(f.Url); 18: web.DownloadFile(f.Url, Path.Combine(myVideos, fileName)); 19: }); 20: } Step 3 (have her open the box) Compile and run. As you can see, the client reference created for the OData service handles almost everything for me. Yeah, I know there is some batch file to download the files, but it relies on cUrl being on the machine – and I wanted an excuse to work with an OData service. Enjoy!

    Read the article

  • Get a culture specific list of month names

    - by erwin21
    A while ago I found a clever way to retrieve a dynamic culture specific list of months names in C# with LINQ. 1: var months = Enumerable.Range(1, 12) 2: .Select(i => new 3: { 4: Month = i.ToString(), 5: MonthName = new DateTime(1, i, 1).ToString("MMMM") 6: }) 7: .ToList(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } It’s fairly simple, for a range of numbers from 1 to 12 a DateTime object is created (year and day doesn’t matter in this case), then the date time object formatted to a full month name with ToString(“MMMM”). In this example an anonymous object is created with a Month and MonthName property. You can use this solution to populate your dropdown list with months or to display a user friendly month name.

    Read the article

  • Azure &ndash; Part 5 &ndash; Repository Pattern for Table Service

    - by Shaun
    In my last post I created a very simple WCF service with the user registration functionality. I created an entity for the user data and a DataContext class which provides some methods for operating the entities such as add, delete, etc. And in the service method I utilized it to add a new entity into the table service. But I didn’t have any validation before registering which is not acceptable in a real project. So in this post I would firstly add some validation before perform the data creation code and show how to use the LINQ for the table service.   LINQ to Table Service Since the table service utilizes ADO.NET Data Service to expose the data and the managed library of ADO.NET Data Service supports LINQ we can use it to deal with the data of the table service. Let me explain with my current example: I would like to ensure that when register a new user the email address should be unique. So I need to check the account entities in the table service before add. If you remembered, in my last post I mentioned that there’s a method in the TableServiceContext class – CreateQuery, which will create a IQueryable instance from a given type of entity. So here I would create a method under my AccountDataContext class to return the IQueryable<Account> which named Load. 1: public class AccountDataContext : TableServiceContext 2: { 3: private CloudStorageAccount _storageAccount; 4:  5: public AccountDataContext(CloudStorageAccount storageAccount) 6: : base(storageAccount.TableEndpoint.AbsoluteUri, storageAccount.Credentials) 7: { 8: _storageAccount = storageAccount; 9:  10: var tableStorage = new CloudTableClient(_storageAccount.TableEndpoint.AbsoluteUri, 11: _storageAccount.Credentials); 12: tableStorage.CreateTableIfNotExist("Account"); 13: } 14:  15: public void Add(Account accountToAdd) 16: { 17: AddObject("Account", accountToAdd); 18: SaveChanges(); 19: } 20:  21: public IQueryable<Account> Load() 22: { 23: return CreateQuery<Account>("Account"); 24: } 25: } The method returns the IQueryable<Account> so that I can perform the LINQ operation on it. And back to my service class, I will use it to implement my validation. 1: public bool Register(string email, string password) 2: { 3: var storageAccount = CloudStorageAccount.FromConfigurationSetting("DataConnectionString"); 4: var accountToAdd = new Account(email, password) { DateCreated = DateTime.Now }; 5: var accountContext = new AccountDataContext(storageAccount); 6:  7: // validation 8: var accountNumber = accountContext.Load() 9: .Where(a => a.Email == accountToAdd.Email) 10: .Count(); 11: if (accountNumber > 0) 12: { 13: throw new ApplicationException(string.Format("Your account {0} had been used.", accountToAdd.Email)); 14: } 15:  16: // create entity 17: try 18: { 19: accountContext.Add(accountToAdd); 20: return true; 21: } 22: catch (Exception ex) 23: { 24: Trace.TraceInformation(ex.ToString()); 25: } 26: return false; 27: } I used the Load method to retrieve the IQueryable<Account> and use Where method to find the accounts those email address are the same as the one is being registered. If it has I through an exception back to the client side. Let’s run it and test from my simple client application. Oops! Looks like we encountered an unexpected exception. It said the “Count” is not support by the ADO.NET Data Service LINQ managed library. That is because the table storage managed library (aka. TableServiceContext) is based on the ADO.NET Data Service and it supports very limit LINQ operation. Although I didn’t find a full list or documentation about which LINQ methods it supports I could even refer a page on msdn here. It gives us a roughly summary of which query operation the ADO.NET Data Service managed library supports and which doesn't. As you see the Count method is not in the supported list. Not only the query operation, there inner lambda expression in the Where method are limited when using the ADO.NET Data Service managed library as well. For example if you added (a => !a.DateDeleted.HasValue) in the Where method to exclude those deleted account it will raised an exception said "Invalid Input". Based on my experience you should always use the simple comparison (such as ==, >, <=, etc.) on the simple members (such as string, integer, etc.) and do not use any shortcut methods (such as string.Compare, string.IsNullOrEmpty etc.). 1: // validation 2: var accountNumber = accountContext.Load() 3: .Where(a => a.Email == accountToAdd.Email) 4: .ToList() 5: .Count; 6: if (accountNumber > 0) 7: { 8: throw new ApplicationException(string.Format("Your account {0} had been used.", accountToAdd.Email)); 9: } We changed the a bit and try again. Since I had created an account with my mail address so this time it gave me an exception said that the email had been used, which is correct.   Repository Pattern for Table Service The AccountDataContext takes the responsibility to save and load the account entity but only for that specific entity. Is that possible to have a dynamic or generic DataContext class which can operate any kinds of entity in my system? Of course yes. Although there's no typical database in table service we can threat the entities as the records, similar with the data entities if we used OR Mapping. As we can use some patterns for ORM architecture here we should be able to adopt the one of them - Repository Pattern in this example. We know that the base class - TableServiceContext provide 4 methods for operating the table entities which are CreateQuery, AddObject, UpdateObject and DeleteObject. And we can create a relationship between the enmity class, the table container name and entity set name. So it's really simple to have a generic base class for any kinds of entities. Let's rename the AccountDataContext to DynamicDataContext and make the type of Account as a type parameter if it. 1: public class DynamicDataContext<T> : TableServiceContext where T : TableServiceEntity 2: { 3: private CloudStorageAccount _storageAccount; 4: private string _entitySetName; 5:  6: public DynamicDataContext(CloudStorageAccount storageAccount) 7: : base(storageAccount.TableEndpoint.AbsoluteUri, storageAccount.Credentials) 8: { 9: _storageAccount = storageAccount; 10: _entitySetName = typeof(T).Name; 11:  12: var tableStorage = new CloudTableClient(_storageAccount.TableEndpoint.AbsoluteUri, 13: _storageAccount.Credentials); 14: tableStorage.CreateTableIfNotExist(_entitySetName); 15: } 16:  17: public void Add(T entityToAdd) 18: { 19: AddObject(_entitySetName, entityToAdd); 20: SaveChanges(); 21: } 22:  23: public void Update(T entityToUpdate) 24: { 25: UpdateObject(entityToUpdate); 26: SaveChanges(); 27: } 28:  29: public void Delete(T entityToDelete) 30: { 31: DeleteObject(entityToDelete); 32: SaveChanges(); 33: } 34:  35: public IQueryable<T> Load() 36: { 37: return CreateQuery<T>(_entitySetName); 38: } 39: } I saved the name of the entity type when constructed for performance matter. The table name, entity set name would be the same as the name of the entity class. The Load method returned a generic IQueryable instance which supports the lazy load feature. Then in my service class I changed the AccountDataContext to DynamicDataContext and that's all. 1: var accountContext = new DynamicDataContext<Account>(storageAccount); Run it again and register another account. The DynamicDataContext now can be used for any entities. For example, I would like the account has a list of notes which contains 3 custom properties: Account Email, Title and Content. We create the note entity class. 1: public class Note : TableServiceEntity 2: { 3: public string AccountEmail { get; set; } 4: public string Title { get; set; } 5: public string Content { get; set; } 6: public DateTime DateCreated { get; set; } 7: public DateTime? DateDeleted { get; set; } 8:  9: public Note() 10: : base() 11: { 12: } 13:  14: public Note(string email) 15: : base(email, string.Format("{0}_{1}", email, Guid.NewGuid().ToString())) 16: { 17: AccountEmail = email; 18: } 19: } And no need to tweak the DynamicDataContext we can directly go to the service class to implement the logic. Notice here I utilized two DynamicDataContext instances with the different type parameters: Note and Account. 1: public class NoteService : INoteService 2: { 3: public void Create(string email, string title, string content) 4: { 5: var storageAccount = CloudStorageAccount.FromConfigurationSetting("DataConnectionString"); 6: var accountContext = new DynamicDataContext<Account>(storageAccount); 7: var noteContext = new DynamicDataContext<Note>(storageAccount); 8:  9: // validate - email must be existed 10: var accounts = accountContext.Load() 11: .Where(a => a.Email == email) 12: .ToList() 13: .Count; 14: if (accounts <= 0) 15: throw new ApplicationException(string.Format("The account {0} does not exsit in the system please register and try again.", email)); 16:  17: // save the note 18: var noteToAdd = new Note(email) { Title = title, Content = content, DateCreated = DateTime.Now }; 19: noteContext.Add(noteToAdd); 20: } 21: } And updated our client application to test the service. I didn't implement any list service to show all notes but we can have a look on the local SQL database if we ran it at local development fabric.   Summary In this post I explained a bit about the limited LINQ support for the table service. And then I demonstrated about how to use the repository pattern in the table service data access layer and make the DataContext dynamically. The DynamicDataContext I created in this post is just a prototype. In fact we should create the relevant interface to make it testable and for better structure we'd better separate the DataContext classes for each individual kind of entity. So it should have IDataContextBase<T>, DataContextBase<T> and for each entity we would have class AccountDataContext<Account> : IDataContextBase<Account>, DataContextBase<Account> { … } class NoteDataContext<Note> : IDataContextBase<Note>, DataContextBase<Note> { … }   Besides the structured data saving and loading, another common scenario would be saving and loading some binary data such as images, files. In my next post I will show how to use the Blob Service to store the bindery data - make the account be able to upload their logo in my example.   Hope this helps, Shaun   All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

    Read the article

  • Working with Timelines with LINQ to Twitter

    - by Joe Mayo
    When first working with the Twitter API, I thought that using SinceID would be an effective way to page through timelines. In practice it doesn’t work well for various reasons. To explain why, Twitter published an excellent document that is a must-read for anyone working with timelines: Twitter Documentation: Working with Timelines This post shows how to implement the recommended strategies in that document by using LINQ to Twitter. You should read the document in it’s entirety before moving on because my explanation will start at the bottom and work back up to the top in relation to the Twitter document. What follows is an explanation of SinceID, MaxID, and how they come together to help you efficiently work with Twitter timelines. The Role of SinceID Specifying SinceID says to Twitter, “Don’t return tweets earlier than this”. What you want to do is store this value after every timeline query set so that it can be reused on the next set of queries.  The next section will explain what I mean by query set, but a quick explanation is that it’s a loop that gets all new tweets. The SinceID is a backstop to avoid retrieving tweets that you already have. Here’s some initialization code that includes a variable named sinceID that will be used to populate the SinceID property in subsequent queries: // last tweet processed on previous query set ulong sinceID = 210024053698867204; ulong maxID; const int Count = 10; var statusList = new List<status>(); Here, I’ve hard-coded the sinceID variable, but this is where you would initialize sinceID from whatever storage you choose (i.e. a database). The first time you ever run this code, you won’t have a value from a previous query set. Initially setting it to 0 might sound like a good idea, but what if you’re querying a timeline with lots of tweets? Because of the number of tweets and rate limits, your query set might take a very long time to run. A caveat might be that Twitter won’t return an entire timeline back to Tweet #0, but rather only go back a certain period of time, the limits of which are documented for individual Twitter timeline API resources. So, to initialize SinceID at too low of a number can result in a lot of initial tweets, yet there is a limit to how far you can go back. What you’re trying to accomplish in your application should guide you in how to initially set SinceID. I have more to say about SinceID later in this post. The other variables initialized above include the declaration for MaxID, Count, and statusList. The statusList variable is a holder for all the timeline tweets collected during this query set. You can set Count to any value you want as the largest number of tweets to retrieve, as defined by individual Twitter timeline API resources. To effectively page results, you’ll use the maxID variable to set the MaxID property in queries, which I’ll discuss next. Initializing MaxID On your first query of a query set, MaxID will be whatever the most recent tweet is that you get back. Further, you don’t know what MaxID is until after the initial query. The technique used in this post is to do an initial query and then use the results to figure out what the next MaxID will be.  Here’s the code for the initial query: var userStatusResponse = (from tweet in twitterCtx.Status where tweet.Type == StatusType.User && tweet.ScreenName == "JoeMayo" && tweet.SinceID == sinceID && tweet.Count == Count select tweet) .ToList(); statusList.AddRange(userStatusResponse); // first tweet processed on current query maxID = userStatusResponse.Min( status => ulong.Parse(status.StatusID)) - 1; The query above sets both SinceID and Count properties. As explained earlier, Count is the largest number of tweets to return, but the number can be less. A couple reasons why the number of tweets that are returned could be less than Count include the fact that the user, specified by ScreenName, might not have tweeted Count times yet or might not have tweeted at least Count times within the maximum number of tweets that can be returned by the Twitter timeline API resource. Another reason could be because there aren’t Count tweets between now and the tweet ID specified by sinceID. Setting SinceID constrains the results to only those tweets that occurred after the specified Tweet ID, assigned via the sinceID variable in the query above. The statusList is an accumulator of all tweets receive during this query set. To simplify the code, I left out some logic to check whether there were no tweets returned. If  the query above doesn’t return any tweets, you’ll receive an exception when trying to perform operations on an empty list. Yeah, I cheated again. Besides querying initial tweets, what’s important about this code is the final line that sets maxID. It retrieves the lowest numbered status ID in the results. Since the lowest numbered status ID is for a tweet we already have, the code decrements the result by one to keep from asking for that tweet again. Remember, SinceID is not inclusive, but MaxID is. The maxID variable is now set to the highest possible tweet ID that can be returned in the next query. The next section explains how to use MaxID to help get the remaining tweets in the query set. Retrieving Remaining Tweets Earlier in this post, I defined a term that I called a query set. Essentially, this is a group of requests to Twitter that you perform to get all new tweets. A single query might not be enough to get all new tweets, so you’ll have to start at the top of the list that Twitter returns and keep making requests until you have all new tweets. The previous section showed the first query of the query set. The code below is a loop that completes the query set: do { // now add sinceID and maxID userStatusResponse = (from tweet in twitterCtx.Status where tweet.Type == StatusType.User && tweet.ScreenName == "JoeMayo" && tweet.Count == Count && tweet.SinceID == sinceID && tweet.MaxID == maxID select tweet) .ToList(); if (userStatusResponse.Count > 0) { // first tweet processed on current query maxID = userStatusResponse.Min( status => ulong.Parse(status.StatusID)) - 1; statusList.AddRange(userStatusResponse); } } while (userStatusResponse.Count != 0 && statusList.Count < 30); Here we have another query, but this time it includes the MaxID property. The SinceID property prevents reading tweets that we’ve already read and Count specifies the largest number of tweets to return. Earlier, I mentioned how it was important to check how many tweets were returned because failing to do so will result in an exception when subsequent code runs on an empty list. The code above protects against this problem by only working with the results if Twitter actually returns tweets. Reasons why there wouldn’t be results include: if the first query got all the new tweets there wouldn’t be more to get and there might not have been any new tweets between the SinceID and MaxID settings of the most recent query. The code for loading the returned tweets into statusList and getting the maxID are the same as previously explained. The important point here is that MaxID is being reset, not SinceID. As explained in the Twitter documentation, paging occurs from the newest tweets to oldest, so setting MaxID lets us move from the most recent tweets down to the oldest as specified by SinceID. The two loop conditions cause the loop to continue as long as tweets are being read or a max number of tweets have been read.  Logically, you want to stop reading when you’ve read all the tweets and that’s indicated by the fact that the most recent query did not return results. I put the check to stop after 30 tweets are reached to keep the demo from running too long – in the console the response scrolls past available buffer and I wanted you to be able to see the complete output. Yet, there’s another point to be made about constraining the number of items you return at one time. The Twitter API has rate limits and making too many queries per minute will result in an error from twitter that LINQ to Twitter raises as an exception. To use the API properly, you’ll have to ensure you don’t exceed this threshold. Looking at the statusList.Count as done above is rather primitive, but you can implement your own logic to properly manage your rate limit. Yeah, I cheated again. Summary Now you know how to use LINQ to Twitter to work with Twitter timelines. After reading this post, you have a better idea of the role of SinceID - the oldest tweet already received. You also know that MaxID is the largest tweet ID to retrieve in a query. Together, these settings allow you to page through results via one or more queries. You also understand what factors affect the number of tweets returned and considerations for potential error handling logic. The full example of the code for this post is included in the downloadable source code for LINQ to Twitter.   @JoeMayo

    Read the article

  • Overloading methods that do logically different things, does this break any major principles?

    - by siva.k
    This is something that's been bugging me for a bit now. In some cases you see code that is a series of overloads, but when you look at the actual implementation you realize they do logically different things. However writing them as overloads allows the caller to ignore this and get the same end result. But would it be more sound to name the methods more explicitly then to write them as overloads? public void LoadWords(string filePath) { var lines = File.ReadAllLines(filePath).ToList(); LoadWords(lines); } public void LoadWords(IEnumerable<string> words) { // loads words into a List<string> based on some filters } Would these methods better serve future developers to be named as LoadWordsFromFile() and LoadWordsFromEnumerable()? It seems unnecessary to me, but if that is better what programming principle would apply here? On the flip side it'd make it so you didn't need to read the signatures to see exactly how you can load the words, which as Uncle Bob says would be a double take. But in general is this type of overloading to be avoided then?

    Read the article

  • Performing a Depth First Search iteratively using async/parallel processing?

    - by Prabhu
    Here is a method that does a DFS search and returns a list of all items given a top level item id. How could I modify this to take advantage of parallel processing? Currently, the call to get the sub items is made one by one for each item in the stack. It would be nice if I could get the sub items for multiple items in the stack at the same time, and populate my return list faster. How could I do this (either using async/await or TPL, or anything else) in a thread safe manner? private async Task<IList<Item>> GetItemsAsync(string topItemId) { var items = new List<Item>(); var topItem = await GetItemAsync(topItemId); Stack<Item> stack = new Stack<Item>(); stack.Push(topItem); while (stack.Count > 0) { var item = stack.Pop(); items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } } return items; } I was thinking of something along these lines, but it's not coming together: var tasks = stack.Select(async item => { items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } }).ToList(); if (tasks.Any()) await Task.WhenAll(tasks); The language I'm using is C#.

    Read the article

  • Loading Entities Dynamically with Entity Framework

    - by Ricardo Peres
    Sometimes we may be faced with the need to load entities dynamically, that is, knowing their Type and the value(s) for the property(ies) representing the primary key. One way to achieve this is by using the following extension methods for ObjectContext (which can be obtained from a DbContext, of course): 1: public static class ObjectContextExtensions 2: { 3: public static Object Load(this ObjectContext ctx, Type type, params Object [] ids) 4: { 5: Object p = null; 6:  7: EntityType ospaceType = ctx.MetadataWorkspace.GetItems<EntityType>(DataSpace.OSpace).SingleOrDefault(x => x.FullName == type.FullName); 8:  9: List<String> idProperties = ospaceType.KeyMembers.Select(k => k.Name).ToList(); 10:  11: List<EntityKeyMember> members = new List<EntityKeyMember>(); 12:  13: EntitySetBase collection = ctx.MetadataWorkspace.GetEntityContainer(ctx.DefaultContainerName, DataSpace.CSpace).BaseEntitySets.Where(x => x.ElementType.FullName == type.FullName).Single(); 14:  15: for (Int32 i = 0; i < ids.Length; ++i) 16: { 17: members.Add(new EntityKeyMember(idProperties[i], ids[i])); 18: } 19:  20: EntityKey key = new EntityKey(String.Concat(ctx.DefaultContainerName, ".", collection.Name), members); 21:  22: if (ctx.TryGetObjectByKey(key, out p) == true) 23: { 24: return (p); 25: } 26:  27: return (p); 28: } 29:  30: public static T Load<T>(this ObjectContext ctx, params Object[] ids) 31: { 32: return ((T)Load(ctx, typeof(T), ids)); 33: } 34: } This will work with both single-property primary keys or with multiple, but you will have to supply each of the corresponding values in the appropriate order. Hope you find this useful!

    Read the article

  • Calling a webservice via Javascript

    - by jeroenb
    If you want to consume a webservice, it's not allways necessary to do a postback. It's even not that hard! 1. Webservice You have to add the scriptservice attribute to the webservice. [System.Web.Script.Services.ScriptService]public class PersonsInCompany : System.Web.Services.WebService { Create a WebMethod [WebMethod] public Person GetPersonByFirstName(string name) { List<Person> personSelect = persons.Where(p => p.FirstName.ToLower().StartsWith(name.ToLower())).ToList(); if (personSelect.Count > 0) return personSelect.First(); else return null; } 2. webpage Add reference to your service to your scriptmanager <script type="text/javascript"> function GetPersonInCompany() { var val = document.getElementById("MainContent_TextBoxPersonName"); PersonsInCompany.GetPersonByFirstName(val.value, FinishCallback); } function FinishCallback(result) { document.getElementById("MainContent_LabelFirstName").innerHTML = result.FirstName; document.getElementById("MainContent_LabelName").innerHTML = result.Name; document.getElementById("MainContent_LabelAge").innerHTML = result.Age; document.getElementById("MainContent_LabelCompany").innerHTML = result.Company; } </script> Add some javascript, where you first call your webservice. Classname.Webmethod = PersonsInCompany.GetPersonByFirstName Add a callback to catch the result from the webservice. And use the result to update your page. <script type="text/javascript"> function GetPersonInCompany() { var val = document.getElementById("MainContent_TextBoxPersonName"); PersonsInCompany.GetPersonByFirstName(val.value, FinishCallback); } function FinishCallback(result) { document.getElementById("MainContent_LabelFirstName").innerHTML = result.FirstName; document.getElementById("MainContent_LabelName").innerHTML = result.Name; document.getElementById("MainContent_LabelAge").innerHTML = result.Age; document.getElementById("MainContent_LabelCompany").innerHTML = result.Company; } </script>   If you have any question, feel free to contact me! You can download the code here.

    Read the article

  • WCF Publish/Subscribe and using callbacks to send data to specific users

    - by manemawanna
    Hello thanks for looking, I'm working on a project at the moment and have become a little stuck. I'm creating a client server app, which allows a client to subscribe to the server to have messages forwarded to it. The issue I'm having is that when the client subscribes I wish for them to only recieve updates that relate to them. The system basically passes messages from a SQL server DB which the server monitors. When a new message is recieved the server should only forward the message to the clients that it applys to, based on whos logged on the client machine. I've had a look and found code samples which sign up for messages to be broadcast across all clients who have subscribed, but not any that show how to identify individual clients and if messages apply to them. If anyone could help or point me in the right direction it would be appreciated. You can now find some of my code below: namespace AnnouncementServiceLibrary { [ServiceContract(CallbackContract = typeof(IMessageCallback))] public interface IMessageCheck { [OperationContract] void MessageCheck(); } } namespace AnnouncementServiceLibrary { public interface IMessageCallback { [OperationContract(IsOneWay = true)] void OnNewMessage(Mess message); } } public bool Subscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); //If they dont already exist in the subscribers list, adds them to it if (!subscribers.Contains(callback)) subscribers.Add(callback); return true; } catch { //Otherwise if an error occurs returns false return false; } } Subscribe/Unsubscribe: private static readonly List<IMessageCallback> subscribers = new List<IMessageCallback>(); /// <summary> /// Unsubscribes the user from recieving new messages when they become avaliable /// </summary> /// <returns>Returns a bool that indicates whether the operation worked or not</returns> public bool Unsubscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); //If they exist in the list of subscribers they are then removed if (subscribers.Contains(callback)) subscribers.Remove(callback); return true; } catch { //Otherwise if an error occurs returns false return false; } } Finally this at the moment isnt't working as basically when a user subscribes as it loops through I want it to filter based on the users userID: #region IMessageCheck Members /// <summary> /// This method checks for new messages recieved based on those who have subscribed for the service /// </summary> public void MessageCheck() { //A continuous loop to keep the method going while(true) { //Changes the thread to a sleep state for 2 mins? Thread.Sleep(200000); //Go through each subscriber based on there callback information subscribers.ForEach(delegate(IMessageCallback callback) { //Checks if the person who wanted the callback can still be communicated with if (((ICommunicationObject)callback).State == CommunicationState.Opened) { //Creates a link to the database and gets the required information List<Mess> mess = new List<Mess>(); List<Message> me; List<MessageLink> messLink; AnnouncementDBDataContext aDb = new AnnouncementDBDataContext(); me = aDb.Messages.ToList(); messLink = aDb.MessageLinks.ToList(); //Query to retrieve any messages which are newer than the time when the last cycle finished var result = (from a in messLink join b in me on a.UniqueID equals b.UniqueID where b.TimeRecieved > _time select new { b.UniqueID, b.Author, b.Title, b.Body, b.Priority, a.Read, b.TimeRecieved }); //Foreach result a new message is created and returned to the PC that subscribed foreach (var a in result) { Mess message = new Mess(a.UniqueID, a.Author, a.Title, a.Body, a.Priority, (bool)a.Read, a.TimeRecieved); callback.OnNewMessage(message); } } //If the requesting PC can't be contacted they are removed from the subscribers list else { subscribers.Remove(callback); } }); //Sets the datetime so the next cycle can measure against to see if new messages have been recieved _time = DateTime.Now; } } #endregion

    Read the article

  • convert the output into an list

    - by prince23
    using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Linq.Expressions; using System.Xml.XPath; using System.Xml.Linq; namespace SampleProgram1 { class Program { static void Main(string[] args) { string xml = @"<people> <person><name>kumar</name><school>fes</school><parent>All</parent></person> <person><name>manju</name><school>fes</school><parent>kumar</parent></person> <person><name>anu</name><school>frank</school><parent>kumar</parent></person> <person><name>anitha</name><school>jss</school><parent>All</parent></person> <person><name>rohit</name><school>frank</school><parent>manju</parent></person> <person><name>anill</name><school>vijaya</school><parent>manju</parent></person> <person><name>vani</name><school>jss</school><parent>kumar</parent></person> <person><name>soumya</name><school>jss</school><parent>kumar</parent></person> <person><name>madhu</name><school>jss</school><parent>rohit</parent></person> <person><name>shiva</name><school>jss</school><parent>rohit</parent></person> <person><name>vanitha</name><school>jss</school><parent>anitha</parent></person> <person><name>anu</name><school>jss</school><parent>anitha</parent></person> </people>"; XDocument document = XDocument.Parse(xml); var people = (from person in document.Descendants("person") select new Person { Name = (string)person.Element("name"), School = (string)person.Element("school"), Parent = (string)person.Element("parent") }).ToList(); var parents = people.Where(p => p.Parent == "All"); Action<Person> findChildren = null; findChildren = person => { List<Person> children = people.Where(p => p.Parent == person.Name).ToList(); person.Children = children; foreach (Person p in children) findChildren(p); }; foreach (Person parent in parents) { findChildren(parent); } Action<Person, int> showChildren = null; showChildren = (person, tabs) => { //Console.WriteLine(new string('\t', tabs) + person.Name); if (person.Children != null) { foreach (Person p in person.Children) showChildren(p, tabs + 1); } }; foreach (Person parent in parents) { showChildren(parent, 0); } // Console.Read(); } } class Person { public string Name { get; set; } public string School { get; set; } public string Parent { get; set; } public List<Person> Children { get; set; } } } this my program where i need to put the output into a list an dthen bind the lsit into gridview can any one help me out in syntax achiveing this one. i am using c# 3.5

    Read the article

  • validating cascading dropdownlist

    - by shruti
    i am working on MVC.Net. in that i have used cascading dropdownlist. I want to do validations for blank field. the view page coding is: Select Category: <%= Html.DropDownList("Makes", ViewData["Makes"] as SelectList,"Select Category")% Select Subcategory: <%= Html.CascadingDropDownList("Models", "Makes")% the code on controller: public ActionResult AddSubCategoryPage() { var makeList = new SelectList(entityObj.Category.ToList(), "Category_id", "Category_name"); ViewData["Makes"] = makeList; // Create Models view data var modelList = new CascadingSelectList(entityObj.Subcategory1.ToList(), "Category_id", "Subcategory_id", "Subcategory_name"); ViewData["Models"] = modelList; return View("AddSubCategoryPage"); } and for that i have made one class: public static class JavaScriptExtensions { public static string CascadingDropDownList(this HtmlHelper helper, string name, string associatedDropDownList) { var sb = new StringBuilder(); // render select tag sb.AppendFormat("<select name='{0}' id='{0}'></select>", name); sb.AppendLine(); // render data array sb.AppendLine("<script type='text/javascript'>"); var data = (CascadingSelectList)helper.ViewDataContainer.ViewData[name]; var listItems = data.GetListItems(); var colArray = new List<string>(); foreach (var item in listItems) colArray.Add(String.Format("{{key:'{0}',value:'{1}',text:'{2}'}}", item.Key, item.Value, item.Text)); var jsArray = String.Join(",", colArray.ToArray()); sb.AppendFormat("$get('{0}').allOptions=[{1}];", name, jsArray); sb.AppendLine(); sb.AppendFormat("$addHandler($get('{0}'), 'change', Function.createCallback(bindDropDownList, $get('{1}')));", associatedDropDownList, name); sb.AppendLine(); sb.AppendLine("</script>"); return sb.ToString(); } } public class CascadingSelectList { private IEnumerable _items; private string _dataKeyField; private string _dataValueField; private string _dataTextField; public CascadingSelectList(IEnumerable items, string dataKeyField, string dataValueField, string dataTextField) { _items = items; _dataKeyField = dataKeyField; _dataValueField = dataValueField; _dataTextField = dataTextField; } public List<CascadingListItem> GetListItems() { var listItems = new List<CascadingListItem>(); foreach (var item in _items) { var key = DataBinder.GetPropertyValue(item, _dataKeyField).ToString(); var value = DataBinder.GetPropertyValue(item, _dataValueField).ToString(); var text = DataBinder.GetPropertyValue(item, _dataTextField).ToString(); listItems.Add(new CascadingListItem(key, value, text)); } return listItems; } } public class CascadingListItem { public CascadingListItem(string key, string value, string text) { this.Key = key; this.Value = value; this.Text = text; } public string Key { get; set; } public string Value { get; set; } public string Text { get; set; } } but when i run the aaplication it gives me following error: Server Error in '/' Application. The parameters dictionary contains a null entry for parameter 'Models' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult AddSubCategoryPage(Int32, System.String, System.String)' in 'CMS.Controllers.HomeController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Parameter name: parameters . plz help me.

    Read the article

  • Dropdownlist post in ASP.NET MVC3 and Entity Framework Model

    - by Josh Blade
    I have 3 tables: RateProfile RateProfileID ProfileName Rate RateID RateProfileID PanelID Other stuff to update Panel PanelID PanelName I have models for each of these. I have an edit page using the RateProfile model. I display the information for RateProfile and also all of the Rates associated with it. This works fine and I can update it fine. However, I also added a dropdown so that I can filter Rates by PanelID. I need it to post back on change so that it can display the filtered rates. I'm using @Html.DropDownList("PanelID", (SelectList)ViewData["PanelDropDown"], new { onchange = "$('#RateForm').submit()" }) for my dropdownlist. Whenever it posts back to my HttpPost Edit method though, it seems to be missing all information about the Rates navigation property. It's weird because I thought it would do exactly what the input/submit button that I have in the form does (which actually passes the entire model back to my HttpPost Edit action and does what I want it to do). The panelID is properly being passed to my HttpPost Edit method and on to the next view, but when I try to query the Model.Rates navigation property is null (only when the post comes from the dropdown. Everything works fine when the post comes from my submit input). Get Edit: public ActionResult Edit(int id, int panelID = 1) { RateProfile rateprofile = db.RateProfiles.Single(r => r.RateProfileID == id); var panels = db.Panels; ViewData["PanelDropDown"] = new SelectList(panels, "PanelID", "PanelName", panelID); ViewBag.PanelID = panelID; return View(rateprofile); } HttpPost Edit: [HttpPost] public ActionResult Edit(RateProfile rateprofile, int panelID) { var panels = db.Panels; ViewData["PanelDropDown"] = new SelectList(panels, "PanelID", "PanelName", panelID); ViewBag.PanelID = panelID; if (ModelState.IsValid) { db.Entry(rateprofile).State = EntityState.Modified; foreach (Rate dimerate in rateprofile.Rates) { db.Entry(dimerate).State = EntityState.Modified; } db.SaveChanges(); return View(rateprofile); } return View(rateprofile); } View: @model PDR.Models.RateProfile @using (Html.BeginForm(null,null,FormMethod.Post, new {id="RateForm"})) { <div> @Html.Label("Panel") @Html.DropDownList("PanelID", (SelectList)ViewData["PanelDropDown"], new { onchange = "$('#RateForm').submit()" }) </div> @{var rates= Model.Rates.Where(a => a.PanelID == ViewBag.PanelID).OrderBy(a => a.minCount).ToList();} @for (int i = 0; i < rates.Count; i++) { <tr> <td> @Html.HiddenFor(modelItem => rates[i].RateProfileID) @Html.HiddenFor(modelItem => rates[i].RateID) @Html.HiddenFor(modelItem => rates[i].PanelID) @Html.EditorFor(modelItem => rates[i].minCount) @Html.ValidationMessageFor(model => rates[i].minCount) </td> <td> @Html.EditorFor(modelItem => rates[i].maxCount) @Html.ValidationMessageFor(model => rates[i].maxCount) </td> <td> @Html.EditorFor(modelItem => rates[i].Amount) @Html.ValidationMessageFor(model => rates[i].Amount) </td> </tr> } <input type="submit" value="Save" /> } To summarize my problem, the below query in my view only works when the post comes from the submit button and not when it comes from my dropdownlist. @{var rates= Model.Rates.Where(a => a.PanelID == ViewBag.PanelID).OrderBy(a => a.minCount).ToList();}

    Read the article

  • Deleting unreferenced child records with nhibernate

    - by Chev
    Hi There I am working on a mvc app using nhibernate as the orm (ncommon framework) I have parent/child entities: Product, Vendor & ProductVendors and a one to many relationship between them with Product having a ProductVendors collection Product.ProductVendors. I currently am retrieving a Product object and eager loading the children and sending these down the wire to my asp.net mvc client. A user will then modify the list of Vendors and post the updated Product back. I am using a custom model binder to generate the modified Product entity. I am able to update the Product fine and insert new ProductVendors. My problem is that dereferenced ProductVendors are not cascade deleted when specifying Product.ProductVendors.Clear() and calling _productRepository.Save(product). The problem seems to be with attaching the detached instance. Here are my mapping files: Product <?xml version="1.0" encoding="utf-8" ?> <id name="Id"> <generator class="guid.comb" /> </id> <version name="LastModified" unsaved-value="0" column="LastModified" /> <property name="Name" type="String" length="250" /> ProductVendors <?xml version="1.0" encoding="utf-8" ?> <id name="Id"> <generator class="guid.comb" /> </id> <version name="LastModified" unsaved-value="0" column="LastModified" /> <property name="Price" /> <many-to-one name="Product" class="Product" column="ProductId" lazy="false" not-null="true" /> <many-to-one name="Vendor" class="Vendor" column="VendorId" lazy="false" not-null="true" /> Custom Model Binder: using System; using Test.Web.Mvc; using Test.Domain; namespace Spoked.MVC { public class ProductUpdateModelBinder : DefaultModelBinder { private readonly ProductSystem ProductSystem; public ProductUpdateModelBinder(ProductSystem productSystem) { ProductSystem = productSystem; } protected override void OnModelUpdated(ControllerContext controllerContext, ModelBindingContext bindingContext) { var product = bindingContext.Model as Product; if (product != null) { product.Category = ProductSystem.GetCategory(new Guid(bindingContext.ValueProvider["Category"].AttemptedValue)); product.Brand = ProductSystem.GetBrand(new Guid(bindingContext.ValueProvider["Brand"].AttemptedValue)); product.ProductVendors.Clear(); if (bindingContext.ValueProvider["ProductVendors"] != null) { string[] productVendorIds = bindingContext.ValueProvider["ProductVendors"].AttemptedValue.Split(','); foreach (string id in productVendorIds) { product.AddProductVendor(ProductSystem.GetVendor(new Guid(id)), 90m); } } } } } } Controller: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Update(Product product) { using (var scope = new UnitOfWorkScope()) { //product.ProductVendors.Clear(); _productRepository.Save(product); scope.Commit(); } using (new UnitOfWorkScope()) { IList<Vendor> availableVendors = _productSystem.GetAvailableVendors(product); productDetailEditViewModel = new ProductDetailEditViewModel(product, _categoryRepository.Select(x => x).ToList(), _brandRepository.Select(x => x).ToList(), availableVendors); } return RedirectToAction("Edit", "Products", new {id = product.Id.ToString()}); } The following test does pass though: [Test] [NUnit.Framework.Category("ProductTests")] public void Can_Delete_Product_Vendors_By_Dereferencing() { Product product; using(UnitOfWorkScope scope = new UnitOfWorkScope()) { Console.Out.WriteLine("Selecting..."); product = _productRepository.First(); Console.Out.WriteLine("Adding Product Vendor..."); product.AddProductVendor(_vendorRepository.First(), 0m); scope.Commit(); } Console.Out.WriteLine("About to delete Product Vendors..."); using (UnitOfWorkScope scope = new UnitOfWorkScope()) { Console.Out.WriteLine("Clearing Product Vendor..."); _productRepository.Save(product); // seems to be needed to attach entity to the persistance manager product.ProductVendors.Clear(); scope.Commit(); } } Going nuts here as I almost have a very nice solution between mvc, custom model binders and nhibernate. Just not seeing my deletes cascaded. Any help greatly appreciated. Chev

    Read the article

  • How can i optimize this recursive method

    - by Tirdyr
    Hi there. I'm trying to make a word puzzle game, and for that i'm using a recursive method to find all possible words in the given letters. The letters is in a 4x4 board. Like this: ABCD EFGH HIJK LMNO The recursive method is called inside this loop: for (int y = 0; y < width; y++) { for (int x = 0; x < height; x++) { myScabble.Search(letters, y, x, width, height, "", covered, t); } } letters is a 2D array of chars. y & x is ints that shows where in the board width & height is also int, that tells the dimensions of the board "" is the string we are trying to make (the word) covered is an array of bools, to check if we allready used that square. t is a List (wich contains all the words to check against). The recursive method that need optimizing: public void Search(char[,] letters, int y, int x, int width, int height, string build, bool[,] covered, List<aWord> tt) { // Dont get outside the bounds if (y >= width || y < 0 || x >= height || x < 0) { return; } // Dont deal with allrady covered squares if (covered[x, y]) { return; } // Get Letter char letter = letters[x, y]; // Append string pass = build + letter; // check if its a possibel word //List<aWord> t = myWords.aWord.Where(w => w.word.StartsWith(pass)).ToList(); List<aWord> t = tt.Where(w => w.word.StartsWith(pass)).ToList(); // check if the list is emphty if (t.Count < 10 && t.Count != 0) { //stop point } if (t.Count == 0) { return; } // Check if its a complete word. if (t[0].word == pass) { //check if its allrdy present in the _found dictinary if (!_found.ContainsKey(pass)) { //if not add the word to the dictionary _found.Add(pass, true); } } // Check to see if there is more than 1 more that matches string pass // ie. are there more words to find. if (t.Count > 1) { // make a copy of the covered array bool[,] cov = new bool[height, width]; for (int i = 0; i < width; i++) { for (int a = 0; a < height; a++) { cov[a, i] = covered[a, i]; } } // Set the current square as covered. cov[x, y] = true; // Continue in all 8 directions. Search(letters, y + 1, x, width, height, pass, cov, t); Search(letters, y, x + 1, width, height, pass, cov, t); Search(letters, y + 1, x + 1, width, height, pass, cov, t); Search(letters, y - 1, x, width, height, pass, cov, t); Search(letters, y, x - 1, width, height, pass, cov, t); Search(letters, y - 1, x - 1, width, height, pass, cov, t); Search(letters, y - 1, x + 1, width, height, pass, cov, t); Search(letters, y + 1, x - 1, width, height, pass, cov, t); } } The code works as i expected it to do, however it is very slow.. it takes about 2 mins to find the words. EDIT: i clarified that the letters array is 2D

    Read the article

  • Inheritance Mapping Strategies with Entity Framework Code First CTP5 Part 1: Table per Hierarchy (TPH)

    - by mortezam
    A simple strategy for mapping classes to database tables might be “one table for every entity persistent class.” This approach sounds simple enough and, indeed, works well until we encounter inheritance. Inheritance is such a visible structural mismatch between the object-oriented and relational worlds because object-oriented systems model both “is a” and “has a” relationships. SQL-based models provide only "has a" relationships between entities; SQL database management systems don’t support type inheritance—and even when it’s available, it’s usually proprietary or incomplete. There are three different approaches to representing an inheritance hierarchy: Table per Hierarchy (TPH): Enable polymorphism by denormalizing the SQL schema, and utilize a type discriminator column that holds type information. Table per Type (TPT): Represent "is a" (inheritance) relationships as "has a" (foreign key) relationships. Table per Concrete class (TPC): Discard polymorphism and inheritance relationships completely from the SQL schema.I will explain each of these strategies in a series of posts and this one is dedicated to TPH. In this series we'll deeply dig into each of these strategies and will learn about "why" to choose them as well as "how" to implement them. Hopefully it will give you a better idea about which strategy to choose in a particular scenario. Inheritance Mapping with Entity Framework Code FirstAll of the inheritance mapping strategies that we discuss in this series will be implemented by EF Code First CTP5. The CTP5 build of the new EF Code First library has been released by ADO.NET team earlier this month. EF Code-First enables a pretty powerful code-centric development workflow for working with data. I’m a big fan of the EF Code First approach, and I’m pretty excited about a lot of productivity and power that it brings. When it comes to inheritance mapping, not only Code First fully supports all the strategies but also gives you ultimate flexibility to work with domain models that involves inheritance. The fluent API for inheritance mapping in CTP5 has been improved a lot and now it's more intuitive and concise in compare to CTP4. A Note For Those Who Follow Other Entity Framework ApproachesIf you are following EF's "Database First" or "Model First" approaches, I still recommend to read this series since although the implementation is Code First specific but the explanations around each of the strategies is perfectly applied to all approaches be it Code First or others. A Note For Those Who are New to Entity Framework and Code-FirstIf you choose to learn EF you've chosen well. If you choose to learn EF with Code First you've done even better. To get started, you can find a great walkthrough by Scott Guthrie here and another one by ADO.NET team here. In this post, I assume you already setup your machine to do Code First development and also that you are familiar with Code First fundamentals and basic concepts. You might also want to check out my other posts on EF Code First like Complex Types and Shared Primary Key Associations. A Top Down Development ScenarioThese posts take a top-down approach; it assumes that you’re starting with a domain model and trying to derive a new SQL schema. Therefore, we start with an existing domain model, implement it in C# and then let Code First create the database schema for us. However, the mapping strategies described are just as relevant if you’re working bottom up, starting with existing database tables. I’ll show some tricks along the way that help you dealing with nonperfect table layouts. Let’s start with the mapping of entity inheritance. -- The Domain ModelIn our domain model, we have a BillingDetail base class which is abstract (note the italic font on the UML class diagram below). We do allow various billing types and represent them as subclasses of BillingDetail class. As for now, we support CreditCard and BankAccount: Implement the Object Model with Code First As always, we start with the POCO classes. Note that in our DbContext, I only define one DbSet for the base class which is BillingDetail. Code First will find the other classes in the hierarchy based on Reachability Convention. public abstract class BillingDetail  {     public int BillingDetailId { get; set; }     public string Owner { get; set; }             public string Number { get; set; } } public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } } public class CreditCard : BillingDetail {     public int CardType { get; set; }                     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } } public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; } } This object model is all that is needed to enable inheritance with Code First. If you put this in your application you would be able to immediately start working with the database and do CRUD operations. Before going into details about how EF Code First maps this object model to the database, we need to learn about one of the core concepts of inheritance mapping: polymorphic and non-polymorphic queries. Polymorphic Queries LINQ to Entities and EntitySQL, as object-oriented query languages, both support polymorphic queries—that is, queries for instances of a class and all instances of its subclasses, respectively. For example, consider the following query: IQueryable<BillingDetail> linqQuery = from b in context.BillingDetails select b; List<BillingDetail> billingDetails = linqQuery.ToList(); Or the same query in EntitySQL: string eSqlQuery = @"SELECT VAlUE b FROM BillingDetails AS b"; ObjectQuery<BillingDetail> objectQuery = ((IObjectContextAdapter)context).ObjectContext                                                                          .CreateQuery<BillingDetail>(eSqlQuery); List<BillingDetail> billingDetails = objectQuery.ToList(); linqQuery and eSqlQuery are both polymorphic and return a list of objects of the type BillingDetail, which is an abstract class but the actual concrete objects in the list are of the subtypes of BillingDetail: CreditCard and BankAccount. Non-polymorphic QueriesAll LINQ to Entities and EntitySQL queries are polymorphic which return not only instances of the specific entity class to which it refers, but all subclasses of that class as well. On the other hand, Non-polymorphic queries are queries whose polymorphism is restricted and only returns instances of a particular subclass. In LINQ to Entities, this can be specified by using OfType<T>() Method. For example, the following query returns only instances of BankAccount: IQueryable<BankAccount> query = from b in context.BillingDetails.OfType<BankAccount>() select b; EntitySQL has OFTYPE operator that does the same thing: string eSqlQuery = @"SELECT VAlUE b FROM OFTYPE(BillingDetails, Model.BankAccount) AS b"; In fact, the above query with OFTYPE operator is a short form of the following query expression that uses TREAT and IS OF operators: string eSqlQuery = @"SELECT VAlUE TREAT(b as Model.BankAccount)                       FROM BillingDetails AS b                       WHERE b IS OF(Model.BankAccount)"; (Note that in the above query, Model.BankAccount is the fully qualified name for BankAccount class. You need to change "Model" with your own namespace name.) Table per Class Hierarchy (TPH)An entire class hierarchy can be mapped to a single table. This table includes columns for all properties of all classes in the hierarchy. The concrete subclass represented by a particular row is identified by the value of a type discriminator column. You don’t have to do anything special in Code First to enable TPH. It's the default inheritance mapping strategy: This mapping strategy is a winner in terms of both performance and simplicity. It’s the best-performing way to represent polymorphism—both polymorphic and nonpolymorphic queries perform well—and it’s even easy to implement by hand. Ad-hoc reporting is possible without complex joins or unions. Schema evolution is straightforward. Discriminator Column As you can see in the DB schema above, Code First has to add a special column to distinguish between persistent classes: the discriminator. This isn’t a property of the persistent class in our object model; it’s used internally by EF Code First. By default, the column name is "Discriminator", and its type is string. The values defaults to the persistent class names —in this case, “BankAccount” or “CreditCard”. EF Code First automatically sets and retrieves the discriminator values. TPH Requires Properties in SubClasses to be Nullable in the Database TPH has one major problem: Columns for properties declared by subclasses will be nullable in the database. For example, Code First created an (INT, NULL) column to map CardType property in CreditCard class. However, in a typical mapping scenario, Code First always creates an (INT, NOT NULL) column in the database for an int property in persistent class. But in this case, since BankAccount instance won’t have a CardType property, the CardType field must be NULL for that row so Code First creates an (INT, NULL) instead. If your subclasses each define several non-nullable properties, the loss of NOT NULL constraints may be a serious problem from the point of view of data integrity. TPH Violates the Third Normal FormAnother important issue is normalization. We’ve created functional dependencies between nonkey columns, violating the third normal form. Basically, the value of Discriminator column determines the corresponding values of the columns that belong to the subclasses (e.g. BankName) but Discriminator is not part of the primary key for the table. As always, denormalization for performance can be misleading, because it sacrifices long-term stability, maintainability, and the integrity of data for immediate gains that may be also achieved by proper optimization of the SQL execution plans (in other words, ask your DBA). Generated SQL QueryLet's take a look at the SQL statements that EF Code First sends to the database when we write queries in LINQ to Entities or EntitySQL. For example, the polymorphic query for BillingDetails that you saw, generates the following SQL statement: SELECT  [Extent1].[Discriminator] AS [Discriminator],  [Extent1].[BillingDetailId] AS [BillingDetailId],  [Extent1].[Owner] AS [Owner],  [Extent1].[Number] AS [Number],  [Extent1].[BankName] AS [BankName],  [Extent1].[Swift] AS [Swift],  [Extent1].[CardType] AS [CardType],  [Extent1].[ExpiryMonth] AS [ExpiryMonth],  [Extent1].[ExpiryYear] AS [ExpiryYear] FROM [dbo].[BillingDetails] AS [Extent1] WHERE [Extent1].[Discriminator] IN ('BankAccount','CreditCard') Or the non-polymorphic query for the BankAccount subclass generates this SQL statement: SELECT  [Extent1].[BillingDetailId] AS [BillingDetailId],  [Extent1].[Owner] AS [Owner],  [Extent1].[Number] AS [Number],  [Extent1].[BankName] AS [BankName],  [Extent1].[Swift] AS [Swift] FROM [dbo].[BillingDetails] AS [Extent1] WHERE [Extent1].[Discriminator] = 'BankAccount' Note how Code First adds a restriction on the discriminator column and also how it only selects those columns that belong to BankAccount entity. Change Discriminator Column Data Type and Values With Fluent API Sometimes, especially in legacy schemas, you need to override the conventions for the discriminator column so that Code First can work with the schema. The following fluent API code will change the discriminator column name to "BillingDetailType" and the values to "BA" and "CC" for BankAccount and CreditCard respectively: protected override void OnModelCreating(System.Data.Entity.ModelConfiguration.ModelBuilder modelBuilder) {     modelBuilder.Entity<BillingDetail>()                 .Map<BankAccount>(m => m.Requires("BillingDetailType").HasValue("BA"))                 .Map<CreditCard>(m => m.Requires("BillingDetailType").HasValue("CC")); } Also, changing the data type of discriminator column is interesting. In the above code, we passed strings to HasValue method but this method has been defined to accepts a type of object: public void HasValue(object value); Therefore, if for example we pass a value of type int to it then Code First not only use our desired values (i.e. 1 & 2) in the discriminator column but also changes the column type to be (INT, NOT NULL): modelBuilder.Entity<BillingDetail>()             .Map<BankAccount>(m => m.Requires("BillingDetailType").HasValue(1))             .Map<CreditCard>(m => m.Requires("BillingDetailType").HasValue(2)); SummaryIn this post we learned about Table per Hierarchy as the default mapping strategy in Code First. The disadvantages of the TPH strategy may be too serious for your design—after all, denormalized schemas can become a major burden in the long run. Your DBA may not like it at all. In the next post, we will learn about Table per Type (TPT) strategy that doesn’t expose you to this problem. References ADO.NET team blog Java Persistence with Hibernate book a { text-decoration: none; } a:visited { color: Blue; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } p.MsoNormal { margin-top: 0in; margin-right: 0in; margin-bottom: 10.0pt; margin-left: 0in; line-height: 115%; font-size: 11.0pt; font-family: "Calibri" , "sans-serif"; }

    Read the article

  • Azure WNS to Win8 - Push Notifications for Metro Apps

    - by JoshReuben
    Background The Windows Azure Toolkit for Windows 8 allows you to build a Windows Azure Cloud Service that can send Push Notifications to registered Metro apps via Windows Notification Service (WNS). Some configuration is required - you need to: Register the Metro app for Windows Live Application Management Provide Package SID & Client Secret to WNS Modify the Azure Cloud App cscfg file and the Metro app package.appxmanifest file to contain matching Metro package name, SID and client secret. The Mechanism: These notifications take the form of XAML Tile, Toast, Raw or Badge UI notifications. The core engine is provided via the WNS nuget recipe, which exposes an API for constructing payloads and posting notifications to WNS. An application receives push notifications by requesting a notification channel from WNS, which returns a channel URI that the application then registers with a cloud service. In the cloud service, A WnsAccessTokenProvider authenticates with WNS by providing its credentials, the package SID and secret key, and receives in return an access token that the provider caches and can reuse for multiple notification requests. The cloud service constructs a notification request by filling out a template class that contains the information that will be sent with the notification, including text and image references. Using the channel URI of a registered client, the cloud service can then send a notification whenever it has an update for the user. The package contains the NotificationSendUtils class for submitting notifications. The Windows Azure Toolkit for Windows 8 (WAT) provides the PNWorker sample pair of solutions - The Azure server side contains a WebRole & a WorkerRole. The WebRole allows submission of new push notifications into an Azure Queue which the WorkerRole extracts and processes. Further background resources: http://watwindows8.codeplex.com/ - Windows Azure Toolkit for Windows 8 http://watwindows8.codeplex.com/wikipage?title=Push%20Notification%20Worker%20Sample - WAT WNS sample setup http://watwindows8.codeplex.com/wikipage?title=Using%20the%20Windows%208%20Cloud%20Application%20Services%20Application – using Windows 8 with Cloud Application Services A bit of Configuration Register the Metro apps for Windows Live Application Management From the current app manifest of your metro app Publish tab, copy the Package Display Name and the Publisher From: https://manage.dev.live.com/Build/ Package name: <-- we need to change this Client secret: keep this Package Security Identifier (SID): keep this Verify the app here: https://manage.dev.live.com/Applications/Index - so this step is done "If you wish to send push notifications in your application, provide your Package Security Identifier (SID) and client secret to WNS." Provide Package SID & Client Secret to WNS http://msdn.microsoft.com/en-us/library/windows/apps/hh465407.aspx - How to authenticate with WNS https://appdev.microsoft.com/StorePortals/en-us/Account/Signup/PurchaseSubscription - register app with dashboard - need registration code or register a new account & pay $170 shekels http://msdn.microsoft.com/en-us/library/windows/apps/hh868184.aspx - Registering for a Windows Store developer account http://msdn.microsoft.com/en-us/library/windows/apps/hh868187.aspx - Picking a Microsoft account for the Windows Store The WNS Nuget Recipe The WNS Recipe is a nuget package that provides an API for authenticating against WNS, constructing payloads and posting notifications to WNS. After installing this package, a WnsRecipe assembly is added to project references. To send notifications using WNS, first register the application at the Windows Push Notifications & Live Connect portal to obtain Package Security Identifier (SID) and a secret key that your cloud service uses to authenticate with WNS. An application receives push notifications by requesting a notification channel from WNS, which returns a channel URI that the application then registers with a cloud service. In the cloud service, the WnsAccessTokenProvider authenticates with WNS by providing its credentials, the package SID and secret key, and receives in return an access token that the provider caches and can reuse for multiple notification requests. The cloud service constructs a notification request by filling out a template class that contains the information that will be sent with the notification, including text and image references.Using the channel URI of a registered client, the cloud service can then send a notification whenever it has an update for the user. var provider = new WnsAccessTokenProvider(clientId, clientSecret); var notification = new ToastNotification(provider) {     ToastType = ToastType.ToastText02,     Text = new List<string> { "blah"} }; notification.Send(channelUri); the WNS Recipe is instrumented to write trace information via a trace listener – configuratively or programmatically from Application_Start(): WnsDiagnostics.Enable(); WnsDiagnostics.TraceSource.Listeners.Add(new DiagnosticMonitorTraceListener()); WnsDiagnostics.TraceSource.Switch.Level = SourceLevels.Verbose; The WAT PNWorker Sample The Azure server side contains a WebRole & a WorkerRole. The WebRole allows submission of new push notifications into an Azure Queue which the WorkerRole extracts and processes. Overview of Push Notification Worker Sample The toolkit includes a sample application based on the same solution structure as the one created by theWindows 8 Cloud Application Services project template. The sample demonstrates how to off-load the job of sending Windows Push Notifications using a Windows Azure worker role. You can find the source code in theSamples\PNWorker folder. This folder contains a full version of the sample application showing how to use Windows Push Notifications using ASP.NET Membership as the authentication mechanism. The sample contains two different solution files: WATWindows.Azure.sln: This solution must be opened with Visual Studio 2010 and contains the projects related to the Windows Azure web and worker roles. WATWindows.Client.sln: This solution must be opened with Visual Studio 11 and contains the Windows Metro style application project. Only Visual Studio 2010 supports Windows Azure cloud projects so you currently need to use this edition to launch the server application. This will change in a future release of the Windows Azure tools when support for Visual Studio 11 is enabled. Important: Setting up the PNWorker Sample Before running the PNWorker sample, you need to register the application and configure it: 1. Register the app: To register your application, go to the Windows Live Application Management site for Metro style apps at https://manage.dev.live.com/build and sign in with your Windows Live ID. In the Windows Push Notifications & Live Connect page, enter the following information. Package Display Name PNWorker.Sample Publisher CN=127.0.0.1, O=TESTING ONLY, OU=Windows Azure DevFabric 2. 3. Once you register the application, make a note of the values shown in the portal for Client Secret,Package Name and Package SID. 4. Configure the app - double-click the SetupSample.cmd file located inside the Samples\PNWorker folder to launch a tool that will guide you through the process of configuring the sample. setup runs a PowerShell script that requires running with administration privileges to allow the scripts to execute in your machine. When prompted, enter the Client Secret, Package Name, and Package Security Identifier you obtained previously and wait until the tool finishes configuring your sample. Running the PNWorker Sample To run this sample, you must run both the client and the server application projects. 1. Open Visual Studio 2010 as an administrator. Open the WATWindows.Azure.sln solution. Set the start-up project of the solution as the cloud project. Run the app in the dev fabric to test. 2. Open Visual Studio 11 and open the WATWindows.Client.sln solution. Run the Metro client application. In the client application, click Reopen channel and send to server. à the application opens the channel and registers it with the cloud application, & the Output area shows the channel URI. 3. Refresh the WebRole's Push Notifications page to see the UI list the newly registered client. 4. Send notifications to the client application by clicking the Send Notification button. Setup 3 command files + 1 powershell script: SetupSample.cmd –> SetupWPNS.vbs –> SetupWPNS.cmd –> SetupWPNS.UpdateWPNSCredentialsInServiceConfiguration.ps1 appears to set PackageName – from manifest Client Id package security id (SID) – from registration Client Secret – from registration The following configs are modified: WATWindows\ServiceConfiguration.Cloud.cscfg WATWindows\ServiceConfiguration.Local.cscfg WATWindows.Client\package.appxmanifest WatWindows.Notifications A class library – it references the following WNS DLL: C:\WorkDev\CountdownValue\AzureToolkits\WATWindows8\Samples\PNWorker\packages\WnsRecipe.0.0.3.0\lib\net40\WnsRecipe.dll NotificationJobRequest A DataContract for triggering notifications:     using System.Runtime.Serialization; using Microsoft.Windows.Samples.Notifications;     [DataContract]     [KnownType(typeof(WnsAccessTokenProvider))] public class NotificationJobRequest     {               [DataMember] public bool ProcessAsync { get; set; }          [DataMember] public string Payload { get; set; }         [DataMember] public string ChannelUrl { get; set; }         [DataMember] public NotificationType NotificationType { get; set; }         [DataMember] public IAccessTokenProvider AccessTokenProvider { get; set; }         [DataMember] public NotificationSendOptions NotificationSendOptions{ get; set; }     } Investigated these types: WnsAccessTokenProvider – a DataContract that contains the client Id and client secret NotificationType – an enum that can be: Tile, Toast, badge, Raw IAccessTokenProvider – get or reset the access token NotificationSendOptions – SecondsTTL, NotificationPriority (enum), isCache, isRequestForStatus, Tag   There is also a NotificationJobSerializer class which basically wraps a DataContractSerializer serialization / deserialization of NotificationJobRequest The WNSNotificationJobProcessor class This class wraps the NotificationSendUtils API – it periodically extracts any NotificationJobRequest objects from a CloudQueue and submits them to WNS. The ProcessJobMessageRequest method – this is the punchline: it will deserialize a CloudQueueMessage into a NotificationJobRequest & send pass its contents to NotificationUtils to SendAsynchronously / SendSynchronously, (and then dequeue the message).     public override void ProcessJobMessageRequest(CloudQueueMessage notificationJobMessageRequest)         { Trace.WriteLine("Processing a new Notification Job Request", "Information"); NotificationJobRequest pushNotificationJob =                 NotificationJobSerializer.Deserialize(notificationJobMessageRequest.AsString); if (pushNotificationJob != null)             { if (pushNotificationJob.ProcessAsync)                 { Trace.WriteLine("Sending the notification asynchronously", "Information"); NotificationSendUtils.SendAsynchronously( new Uri(pushNotificationJob.ChannelUrl),                         pushNotificationJob.AccessTokenProvider,                         pushNotificationJob.Payload,                         result => this.ProcessSendResult(pushNotificationJob, result),                         result => this.ProcessSendResultError(pushNotificationJob, result),                         pushNotificationJob.NotificationType,                         pushNotificationJob.NotificationSendOptions);                 } else                 { Trace.WriteLine("Sending the notification synchronously", "Information"); NotificationSendResult result = NotificationSendUtils.Send( new Uri(pushNotificationJob.ChannelUrl),                         pushNotificationJob.AccessTokenProvider,                         pushNotificationJob.Payload,                         pushNotificationJob.NotificationType,                         pushNotificationJob.NotificationSendOptions); this.ProcessSendResult(pushNotificationJob, result);                 }             } else             { Trace.WriteLine("Could not deserialize the notification job", "Error");             } this.queue.DeleteMessage(notificationJobMessageRequest);         } Investigation of NotificationSendUtils class - This is the engine – it exposes Send and a SendAsyncronously overloads that take the following params from the NotificationJobRequest: Channel Uri AccessTokenProvider Payload NotificationType NotificationSendOptions WebRole WebRole is a large MVC project – it references WatWindows.Notifications as well as the following WNS DLL: \AzureToolkits\WATWindows8\Samples\PNWorker\packages\WnsRecipe.0.0.3.0\lib\net40\NotificationsExtensions.dll Controllers\PushNotificationController.cs Notification related namespaces:     using Notifications;     using NotificationsExtensions;     using NotificationsExtensions.BadgeContent;     using NotificationsExtensions.RawContent;     using NotificationsExtensions.TileContent;     using NotificationsExtensions.ToastContent;     using Windows.Samples.Notifications; TokenProvider – initialized from the Azure RoleEnvironment:   IAccessTokenProvider tokenProvider = new WnsAccessTokenProvider(         RoleEnvironment.GetConfigurationSettingValue("WNSPackageSID"),         RoleEnvironment.GetConfigurationSettingValue("WNSClientSecret")); SendNotification method – calls QueuePushMessage method to create and serialize a NotificationJobRequest and enqueue it in a CloudQueue [HttpPost]         public ActionResult SendNotification(             [ModelBinder(typeof(NotificationTemplateModelBinder))] INotificationContent notification,             string channelUrl,             NotificationPriority priority = NotificationPriority.Normal)         {             var payload = notification.GetContent();             var options = new NotificationSendOptions()             {                 Priority = priority             };             var notificationType =                 notification is IBadgeNotificationContent ? NotificationType.Badge :                 notification is IRawNotificationContent ? NotificationType.Raw :                 notification is ITileNotificationContent ? NotificationType.Tile :                 NotificationType.Toast;             this.QueuePushMessage(payload, channelUrl, notificationType, options);             object response = new             {                 Status = "Queued for delivery to WNS"             };             return this.Json(response);         } GetSendTemplate method: Create the cshtml partial rendering based on the notification type     [HttpPost]         public ActionResult GetSendTemplate(NotificationTemplateViewModel templateOptions)         {             PartialViewResult result = null;             switch (templateOptions.NotificationType)             {                 case "Badge":                     templateOptions.BadgeGlyphValueContent = Enum.GetNames(typeof( GlyphValue));                     ViewBag.ViewData = templateOptions;                     result = PartialView("_" + templateOptions.NotificationTemplateType);                     break;                 case "Raw":                     ViewBag.ViewData = templateOptions;                     result = PartialView("_Raw");                     break;                 case "Toast":                     templateOptions.TileImages = this.blobClient.GetAllBlobsInContainer(ConfigReader.GetConfigValue("TileImagesContainer")).OrderBy(i => i.FileName).ToList();                     templateOptions.ToastAudioContent = Enum.GetNames(typeof( ToastAudioContent));                     templateOptions.Priorities = Enum.GetNames(typeof( NotificationPriority));                     ViewBag.ViewData = templateOptions;                     result = PartialView("_" + templateOptions.NotificationTemplateType);                     break;                 case "Tile":                     templateOptions.TileImages = this.blobClient.GetAllBlobsInContainer(ConfigReader.GetConfigValue("TileImagesContainer")).OrderBy(i => i.FileName).ToList();                     ViewBag.ViewData = templateOptions;                     result = PartialView("_" + templateOptions.NotificationTemplateType);                     break;             }             return result;         } Investigated these types: ToastAudioContent – an enum of different Win8 sound effects for toast notifications GlyphValue – an enum of different Win8 icons for badge notifications · Infrastructure\NotificationTemplateModelBinder.cs WNS Namespace references     using NotificationsExtensions.BadgeContent;     using NotificationsExtensions.RawContent;     using NotificationsExtensions.TileContent;     using NotificationsExtensions.ToastContent; Various NotificationFactory derived types can server as bindable models in MVC for creating INotificationContent types. Default values are also set for IWideTileNotificationContent & IToastNotificationContent. Type factoryType = null;             switch (notificationType)             {                 case "Badge":                     factoryType = typeof(BadgeContentFactory);                     break;                 case "Tile":                     factoryType = typeof(TileContentFactory);                     break;                 case "Toast":                     factoryType = typeof(ToastContentFactory);                     break;                 case "Raw":                     factoryType = typeof(RawContentFactory);                     break;             } Investigated these types: BadgeContentFactory – CreateBadgeGlyph, CreateBadgeNumeric (???) TileContentFactory – many notification content creation methods , apparently one for every tile layout type ToastContentFactory – many notification content creation methods , apparently one for every toast layout type RawContentFactory – passing strings WorkerRole WNS Namespace references using Notifications; using Notifications.WNS; using Windows.Samples.Notifications; OnStart() Method – on Worker Role startup, initialize the NotificationJobSerializer, the CloudQueue, and the WNSNotificationJobProcessor _notificationJobSerializer = new NotificationJobSerializer(); _cloudQueueClient = this.account.CreateCloudQueueClient(); _pushNotificationRequestsQueue = _cloudQueueClient.GetQueueReference(ConfigReader.GetConfigValue("RequestQueueName")); _processor = new WNSNotificationJobProcessor(_notificationJobSerializer, _pushNotificationRequestsQueue); Run() Method – poll the Azure Queue for NotificationJobRequest messages & process them:   while (true)             { Trace.WriteLine("Checking for Messages", "Information"); try                 { Parallel.ForEach( this.pushNotificationRequestsQueue.GetMessages(this.batchSize), this.processor.ProcessJobMessageRequest);                 } catch (Exception e)                 { Trace.WriteLine(e.ToString(), "Error");                 } Trace.WriteLine(string.Format("Sleeping for {0} seconds", this.pollIntervalMiliseconds / 1000)); Thread.Sleep(this.pollIntervalMiliseconds);                                            } How I learned to appreciate Win8 There is really only one application architecture for Windows 8 apps: Metro client side and Azure backend – and that is a good thing. With WNS, tier integration is so automated that you don’t even have to leverage a HTTP push API such as SignalR. This is a pretty powerful development paradigm, and has changed the way I look at Windows 8 for RAD business apps. When I originally looked at Win8 and the WinRT API, my first opinion on Win8 dev was as follows – GOOD:WinRT, WRL, C++/CX, WinJS, XAML (& ease of Direct3D integration); BAD: low projected market penetration,.NET lobotomized (Only 8% of .NET 4.5 classes can be used in Win8 non-desktop apps - http://bit.ly/HRuJr7); UGLY:Metro pascal tiles! Perhaps my 80s teenage years gave me a punk reactionary sense of revulsion towards the Partridge Family 70s style that Metro UX seems to have appropriated: On second thought though, it simplifies UI dev to a single paradigm (although UX guys will need to change career) – you will not find an easier app dev environment. Speculation: If LightSwitch is going to support HTML5 client app generation, then its a safe guess to say that vnext will support Win8 Metro XAML - a much easier port from Silverlight XAML. Given the VS2012 LightSwitch integration as a thumbs up from the powers that be at MS, and given that Win8 C#/XAML Metro apps tend towards a streamlined 'golden straight-jacket' cookie cutter app dev style with an Azure back-end supporting Win8 push notifications... --> its easy to extrapolate than LightSwitch vnext could well be the Win8 Metro XAML to Azure RAD tool of choice! The hook is already there - :) Why else have the space next to the HTML Client box? This high level of application development abstraction will facilitate rapid app cookie-cutter architecture-infrastructure frameworks for wrapping any app. This will allow me to avoid too much XAML code-monkeying around & focus on my area of interest: Technical Computing.

    Read the article

  • IEnumerable<CustomType> in PowerShell

    - by svick
    I'm trying to use Enumerable.ToList() in PowerShell. Apparently, to do that, I have to explicitly convert the object to IEnumerable<CustomType>, but I am unable to do that. It seems I can't correctly write IEnumerable<CustomType> in PowerShell. Both IEnumerable<string> and CustomType itself work correctly (the custom type I'm trying to use is called WpApiLib.Page), so I don't know what can I be doing wrong. PS C:\Users\Svick> [Collections.Generic.IEnumerable``1[System.String]] IsPublic IsSerial Name BaseType -------- -------- ---- -------- True False IEnumerable`1 PS C:\Users\Svick> [WpApiLib.Page] IsPublic IsSerial Name BaseType -------- -------- ---- -------- True True Page System.Object PS C:\Users\Svick> [Collections.Generic.IEnumerable``1[WpApiLib.Page]] Unable to find type [Collections.Generic.IEnumerable`1[WpApiLib.Page]]: make su re that the assembly containing this type is loaded. At line:1 char:51 + [Collections.Generic.IEnumerable``1[WpApiLib.Page]] <<<<

    Read the article

  • WCF "DataContext accessed after Dispose"

    - by David Ward
    I have an application with numerous WCF services that make use of LINQ-To-SQL as the data access model. I am having lots of problems with the "DataContext accessed after Dispose" exception. I understand what this exception is and that it is occurring because I have not "initialised" the data that is trying to be accessed. I've read many articles that suggest that I called ToList() on any arrays before the parent object is returned by the service. My issue is that I am getting this exception and I don't know where it is originating from and therefore I don't know what hasn't been initialised. Can anyone advise how best to identify the root cause? (I have used the MS Service Trace Viewer and this doesn't seem to give me any further information)

    Read the article

  • LINQ To SQL exception: Local sequence cannot be used in LINQ to SQL implementation of query operator

    - by pcampbell
    Consider this LINQ To SQL query. It's intention is to take a string[] of search terms and apply the terms to a bunch of different fields on the SQL table: string[] searchTerms = new string[] {"hello","world","foo"}; List<Cust> = db.Custs.Where(c => searchTerms.Any(st => st.Equals(c.Email)) || searchTerms.Any(st => st.Equals(c.FirstName)) || searchTerms.Any(st => st.Equals(c.LastName)) || searchTerms.Any(st => st.Equals(c.City)) || searchTerms.Any(st => st.Equals(c.Postal)) || searchTerms.Any(st => st.Equals(c.Phone)) || searchTerms.Any(st => c.AddressLine1.Contains(st)) ) .ToList(); An exception is raised: Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator Question: Why is this exception raised, and how can the query be rewritten to avoid this exception?

    Read the article

  • Linq Problem - Sequence contains no matching element

    - by Pino
    Ok I have the following, set-up and am recieving the following error. returnData.Options = this.ProductOptions.Select(o => o.ToDataModel()).ToList(); This line of code should do a conversion from DAL Entity (Subsonic) to a ViewModel. However I am recieving the following error message Server Error in '/' Application. Sequence contains no matching element Now, I've checked and the this.ProductOptions variable contains 3 results. Whats does this error meen and how can I debug it?

    Read the article

  • Handle Union of List in C# with duplicates

    - by user320587
    Hi, I am trying to understand how to handle union or merge of two lists that can have duplicates. For example, List1 has { A, B, C} and List2 has { B, C, D }. I tried to use the Union operation and got a new list with values (A, B, C, D}. However, I need the B & C values from the second list, not first one. Is there a way to specify the union method, which duplicate value to use. The code I am using now is var newList = List1.Union<Object>(List2).ToList(); Thanks for any help. Javid

    Read the article

< Previous Page | 6 7 8 9 10 11 12 13 14 15 16 17  | Next Page >