Could not find an implementation of the query pattern

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.

Is the tblPersoon implementing IEnumerable<T>? You may need to do it using:

var query = (from p in tblPersoon.Cast<Person>() 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<T>

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 => p.id == id).Single();
    // ...

You may need to add a using statement to the file. The default Silverlight class template doesn't include it:

using System.Linq;

Make sure these references are included:

• System.Data.Linq
• System.Data.Entity

Then add the using statement

using System.Linq;

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

using System.Linq;

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.

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();

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<Contact> Contacts { get; set; } and suddenly the query was recognized.

---

This is probably what k.m says in his answer, but since he mentioned IEnumerable<t> and not DbSet<<YourDomainObject>> I had to dig around in the code for a couple hours to find the line that caused this headache.

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.

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.

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<OBJ> OBJs { get; set; }

which should've been:

public virtual DbSet<OBJ> 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.