Projection over property named Id causes null results

[Jens Pettersson]

Hello. We're experiencing a weird behaviour when using a query with a projection that does a Select over a property called Id. It causes NULL results (from the Select) in EVERY scenario we can test, except when I try to run it as a unit test inside the Raven test project in the official repo. That's why the repro isn't a unit test in your code base.

Here's our setup:

Client: 4.0.1 Stable

Server: 4.0.0

We have  a User document that has a list of Tags. Each Tag has an Id-property, but the Tag isn't a document itself (could be a reference object where the Id points to another document, but it isn't in this example):

public class User

{

    public string Id { get; set; }

    public List<Tag> Tags { get; set; }

}

public class Tag

{

    public string Id { get; set; }

    public string Name { get; set; }

}

With the following program:

using (var session = documentStore.OpenAsyncSession())

{

    var user = new User

    {

        Id = "users/1",

        Tags = new List<Tag>

        {

            new Tag

            {

                Id = "tag-id1", 

                Name = "Tag name"

            }

        }

    };

    await session.StoreAsync(user, "users/1");

    await session.SaveChangesAsync();

}

using (var session = documentStore.OpenAsyncSession())

{

    var query = session.Query<User>();

    var projection = from user in query

                        let tagIds = user.Tags.Select(x => x.Id)

                        let tags = user.Tags.Select(x => x.Name)

                        select new

                        {

                            UserId = user.Id,

                            Tags = tags,

                            TagIds = tagIds

                        };

    var result = await projection.FirstAsync();

}

The expectation here is that the result would be:

{
  UserId: "users/1",
  Tags: ["Tag name"],
  TagIds: ["tag-id1"]
}

however, what we get when running this query is:

{
  UserId: "users/1",
  Tags: ["Tag name"],
  TagIds: [null]
}

If I change the property called Id on the Tag class to something else it works as expected.

Here are some images:

Property not called Id:

When looking at the generate RQL code for the different projections, there are a couple of differences:

With a property not called "Id":

{declare function output(user) {

var tagIds = user.Tags.map(function(x){return x.NotJustId;});

var tags = user.Tags.map(function(x){return x.Name;});

return { UserId : id(user), Tags : tags, TagIds : tagIds };

}

from Users as user select output(user)}

vs. a property called "Id":

{declare function output(user) {

var tagIds = user.Tags.map(function(x){return id(x);});

var tags = user.Tags.map(function(x){return x.Name;});

return { UserId : id(user), Tags : tags, TagIds : tagIds };

}

from Users as user select output(user)}

What really bugs me is that the second generated RQL returns the expected results when running it as a test in the Raven code base inheriting from "RavenTestBase".

I've got an example at: https://github.com/jenspettersson/RavenPerfs/tree/master/Bugs/Raven4.Projections.Tests/Raven4.Projections.Tests

Any ideas?

//J

[Marko Lahma]

You need server to be of version 4.0.1 as this projection is done on server side. Fix made it to version 4.0.1

-Marko

[Jens Pettersson]

Ah ok! I don't see the 4.0.1 Server version on https://ravendb.net/download yet...

[Marko Lahma]

Hmm.. it used to be there, I have one downloaded myself. But you should be fine with nightly - they are all bug fixes and for me at least nightlies work better for some specific use cases I have.

-Marko

[Oren Eini (Ayende Rahien)]

Use the nightly, yes. We had a missed update for 4.0.1 so we pulled it for 4.0.2 that should be out soon

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Oren Eini l CEO l Mobile: + 972-52-548-6969

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[Jens Pettersson]

Thanks guys. It explains a lot (about why it worked in a unit test in the official code base and hence, I'm not crazy)

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