SELECT Distinct CarMakes from table using LINQ

Question

I have a table that has CarMake, CarModels and several other columns. I wan to select distinct carmake only.
What I have done:

public IEnumerable<EbimaCarMakesAndModel> GetAll()
{
            var data = (from dbo in context.EbimaCarMakesAndModels where dbo.Listed == "Y" select dbo.CarMake).Distinct().OrderBy(name => name);

            return (IEnumerable<EbimaCarMakesAndModel>)data;
}

but i get an error as:

InvalidCastException: Unable to cast object of type 'Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1[System.String]' to type 'System.Collections.Generic.IEnumerable`1[motor_backend.Models.EbimaCarMakesAndModel]'.

Answer 1

If CarMake to be returned is a string, then the function should be:

public IEnumerable<string> GetAll()
{
   return 
        context.EbimaCarMakesAndModels
             .Where( m => m.Listed == "Y" )
             .Select( m => m.CarMake )
             .Distinct( )
             .OrderBy( n => n );
}

Give more details if this does not work.

Answer 2

InvalidCastException: Unable to cast object of type 'Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable1[System.String]' to type 'System.Collections.Generic.IEnumerable1[motor_backend.Models.EbimaCarMakesAndModel]'.

var data = (from dbo in context.EbimaCarMakesAndModels where dbo.Listed == "Y" select dbo.CarMake).Distinct().OrderBy(name => name)

What 'data' contains after the query is 'string' data, and it's not a collection of motor_backend.Models.EbimaCarMakesAndModel objects.

the 'select dbo.CarMake' is maybe just returning 'name' data -- string.

var data = (from dbo in context.EbimaCarMakesAndModels.where(a => a.Listed == "Y").Distinct(a => a.CarMake).OrderBy(a => a.name)) select dbo).ToList();

It's going to be something like above using Linq and lambda expressions. You may have to play with the syntax a little bit.

https://www.c-sharpcorner.com/article/writing-complex-queries-using-linq-and-lambda/