Why am I not getting .CopyToDataTable() in Linq Query()

Question

This following code example is borrowed from MSDN here. I am not getting query.CopyToDataTable() available in my code. (see the commented line in my following code).

Answer 1

You need to reference the System.Data.DataSetExtensions assembly and use the System.Data namespace.

Answer 2

This issue for me was caused by using Dotnet Core 2.0, which appears to have no way to turn an IEnumerable back into a DataTable after it's converted.

Just adding this for anyone that comes across this question with the same issue.

Answer 3

Navigating further into MSDN online brings me to this page: http://msdn.microsoft.com/en-us/library/system.data.datatableextensions.aspx

It says its in the System.Data namespace (using System.Data) and you need to reference the System.Data.DataSetExtensions.dll.

Answer 4

It exists in a specific namespace are you importing it?

System.Data.DataTableExtensions.CopyToDataTable() 

Also confirm the addition of this reference

System.Data.DataSetExtensions 

Answer 5

I think that's because your creating a anonymous type to hold the Field object. Try this:

    var query = from SPhysician in dtPhysicianServer.AsEnumerable()
                join CPhysician in dtPhysicianClient.AsEnumerable()
                on SPhysician.Field<string>("PhysicianNumber") equals
                    CPhysician.Field<string>("PhysicianNumber")
                select CPhysician;

    DataTable FilterDt = query.CopyToDataTable();

Definition of CopyToDataTable<T>:

public static DataTable CopyToDataTable<T>(
    this IEnumerable<T> source
)
where T : DataRow

So what you select with the query must be of type IEnumerable<T> where T extends DataRow

Answer 6

Have you referenced System.Data.DataSetExtensions assembly? This extension method is defined there.