Entity Framework scalar function mapping

问题

I have scalar function:

CREATE FUNCTION [dbo].[CheckLocation]
(
    @locationId Int
)
RETURNS bit
AS
BEGIN
    //code
END

I want to use it in Entity Framework context.

I have added this in the *.edmx file:

<Function Name="CheckLocation" ReturnType="bit" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="true" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo" >
<Parameter Name="locationId" Type="int" Mode="In" />
</Function>

I have also created a partial class with method decorated with EdmFunctionAttribute:

public partial class MainModelContainer
{
    [EdmFunction("MainModel.Store", "CheckLocation")]
    public bool CheckLocation(int locationId)
    {
        throw new NotSupportedException("Direct calls not supported");
    }
}

I try to use this function like this:

Context.CheckLocation(locationId);

And get NotSupportedException("Direct calls not supported"). It works within Select method, but it does not suit me. Help please! How can I call this function without select method?

回答1:

you need to access it as a select

var students = context.Locations
    .Select ( new  {  location= CheckLocation(locationId)}):

来源：https://stackoverflow.com/questions/12393085/entity-framework-scalar-function-mapping