Group by multiple columns?

[jotab123]

Hi!

I'm working on group by queries on sqlserver. I'm trying to create groups with multiple columns dynamically and I don't know how I can do it.

Example:

Model

    public class Element
    {
        [Key]
        public int Id { get; set; }
        public double Attribute1 { get; set; }
        public double Attribute2 { get; set; }
    }

Queries

I need this query result:
db.Element.GroupBy(el => new { el.Attribute1, el.Attribute2 })

Dynamically:
db.Element.GroupBy("new(Attribute1, Attribute2)")...?

Is it possible?

Thank you very much!

[StefH]

Should be indeed something like:
var groupResult2 = queryable.GroupBy("new (NumberPropertyAsKey, StringPropertyAsKey)");

See unit-test https://github.com/StefH/System.Linq.Dynamic.Core/blob/master/test/System.Linq.Dynamic.Core.Tests/QueryableTests.GroupBy.cs

[jotab123]

I think so...but, check the output.

[jotab123]

I was doing tests with Elements in memory and It works! I'm gonna report it to EntityFramework Core team.

Great job!

[StefH]

Which version from EntityFramework Core do you use?

[jotab123]

1.0.0 Final version.
I uploaded the full project here: https://github.com/jotab123/GroupByError

[StefH]

The tests in your example project looks valid? I'll check what's happening.

[jotab123]

There are no message error, but the query database result is wrong. It should be four groups instead of ten.

 //List test.
var resultList1 = ElementsList.GroupBy(el => new { el.Attribute1, el.Attribute2 });     //CORRECT
var resultList2 = ElementsList.AsQueryable().GroupBy("new(Attribute1, Attribute2)");    //CORRECT

 //Database tests.
var resultDb1 = db.Element.GroupBy(el => new { el.Attribute1, el.Attribute2 });         //CORRECT
var resultDb2 = db.Element.GroupBy("new(Attribute1, Attribute2)");                      //WRONG

Thank you!

[StefH]

The "resultDb2" is indeed wrong, but I wonder if this is a problem with 'EntityFramework Core', it looks more an issue for System.Linq.Dynamic.Core ?

[jotab123]

I'm not sure where the problem is, sorry. Would be great if you could check your extension method!

[StefH]

I'll take a look.

[StefH]

For the old (6.1.3) EF, it works fine. (I did add a test project)

[StefH]

@jotab123 I tested with EF Core 1.0.1 and it still does not work, even introduced other issue, see
dotnet/efcore#6620

[jogibear9988]

it's fixed in ef now so can be closed?

[StefH]

It's fixed in the 1.1 preview version. I made a new branch in this project to test it.

However, best to keep this issue open until the final EF Core 1.1 is published.

[StefH]

Tested successfully for 1.1 preview.

[jotab123]

Great!

[StefH]

However, best to keep this issue open until the final EF Core 1.1 is published.

[StefH]

Solved in https://www.nuget.org/packages/Microsoft.EntityFrameworkCore.DynamicLinq/1.0.3.3