Could not find an implementation of the query pattern

Question

In my silverlight application I am trying to create a database connection using LINQ  First I add a new LINQ to SQL class  and drag my table called  tblPersoon  into it   Then in my service file I try to execute the following query    OperationContract  public tblPersoon GetPersoonByID string id        var query    from p in tblPersoon where p id    id select p  Single      But at tblPersoon it gives me the following error      Could not find an implementation of the query pattern for source type    SilverlightApplication1 Web tblPersoon     Where  not found    And even when I try the following   var query    from p in tblPersoon select p  Single      It gives me an error saying  Select  not found   Code for the generated class for my table can be found here  http   pastebin com edx3XRhi  What is causing this and how would I possibly solve this   Thank you

User · Answer

I had the same error  but for me  it was attributed to having a database and a table that were named the same   When I added the ADO  NET Entity Object to my project  it misgenerated what I wanted in my database context file      Table public virtual DbSet lt OBJ gt  OBJs   get  set      which should ve been   public virtual DbSet lt OBJ gt  OBJ   get  set      And      Database  public object OBJ   get  internal set      which I actually didn t really need  so I commented it out   I was trying to pull in my table like this  in my controller  when I got my error   protected Model1 db   new Model1     public ActionResult Index         var obj           from p in db OBJ         orderby p OBJ ID descending         select p       return View obj       I corrected my database context and all was fine  after that

User · Answer

Is the tblPersoon implementing IEnumerable lt T gt   You may need to do it using   var query    from p in tblPersoon Cast lt Person gt    select p  Single      This kind of error  Could not find an implementation of the query pattern  usually occurs when    You are missing LINQ namespace usage  using System Linq  Type you are querying does not implement IEnumerable lt T gt    Edit   Apart from fact you query type  tblPersoon  instead of property tblPersoons  you also need an context instance  class that defines tblPersoons property   like this     public tblPersoon GetPersoonByID string id        var context   new DataClasses1DataContext        var query   context tblPersoons Where p   gt  p id    id  Single

User · Answer

For those of you  like me  that wasted too much time from this error   I had received the same error   Could not find implementation of query Pattern for source type  DbSet   but the solution for me was fixing a mistake at the DbContext level   When I created my context I had this   public class ContactContext   DbContext               public ContactContext     base                public DbSet Contacts   get  set            And my Repository  I was following a Repository pattern in ASP NET guide  looked like this   public Contact FindById int id                       var contact   from c in  db Contacts where c Id    id select c          return contact          My issue came from the initial setup of my DbContext  when I used DbSet as a generic instead of the type   I changed public DbSet Contacts   get  set    to public DbSet lt Contact gt  Contacts   get  set    and suddenly the query was recognized     This is probably what k m says in his answer  but since he mentioned IEnumerable lt t gt  and not DbSet lt  lt YourDomainObject gt  gt  I had to dig around in the code for a couple hours to find the line that caused this headache

User · Answer

You are missing an equality   var query    from p in tblPersoon where p id    5 select p  Single      where clause must result in a boolean   OR you should not be using where at all   var query    from p in tblPersoon select p  Single

User · Answer

I had a similar issue with generated strongly typed datasets  the full error message was      Could not find an implementation of the query pattern for    source type  MyApp InvcHeadDataTable     Where  not found     Consider explicitly specifying the type of the range variable  row     From my code           var x               from row in ds InvcHead             where row Company    Session CompanyID             select row    So I did as it suggested and explicitly specified the type           var x               from MyApp InvcHeadRow row in ds InvcHead             where row Company    Session CompanyID             select row    Which worked a treat

User · Answer

You must have forgotten to add a using statement to the file like this  using System Linq

User · Answer

You may need to add a using statement to the file  The default Silverlight class template doesn t include it   using System Linq

User · Answer

Make sure these references are included    System Data Linq  System Data Entity    Then add the using statement  using System Linq

User · Answer

I had the same error as described by title  but for me it was simply installing Microsoft access 12 0 oledb redistributable to use with LinqToExcel

User · Answer

Hi easiest way to do this is to convert this IEnumerable into a Queryable  If it is a queryable  then performing queries becomes easy   Please check this code   var result    from s in  ctx ScannedDatas AsQueryable                                 where s Data    scanData                               select s Id  FirstOrDefault                    return  Match Found     Make sure you include System Linq  This way your error will be resolved

[c#] Could not find an implementation of the query pattern

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