Many-many association on the same model (like user_user) doesn't work

[FedjaVitko]

The document inside the user_user collection only contains one user field. Should it not contain two user fields?

Steps to replicate the issue:

1. Create two users. (POST /user)
2. Add the second user as a friend of the first one. (POST /user/{firstUserId}/user) { childId: secondUserId })
3. Get the friends of the firstUser. (GET /user/{firstUserId}/user)
4. The response object is empty. No friends get returned.

[JKHeadley]

Hi @TheoVitkovskiy, I've been super busy lately but I will try to look into this. In the meantime, would you mind posting your code for the user model?

[FedjaVitko]

Hi @TheoVitkovskiy, I've been super busy lately but I will try to look into this. In the meantime, would you mind posting your code for the user model?

Hi @JKHeadley, for this I just used the example from the documentation https://resthapi.com/docs/associations.html. You find it under the Linking Models section. In my specific use case I'm doing the same, but with book sections. Here is my code for the section model.

[FedjaVitko]

Hi @TheoVitkovskiy, I've been super busy lately but I will try to look into this. In the meantime, would you mind posting your code for the user model?

Hi @JKHeadley, for this I just used the example from the documentation https://resthapi.com/docs/associations.html. You find it under the Linking Models section. In my specific use case I'm doing the same, but with book sections. Here is my code for the section model.

function(mongoose) {
const modelName = 'section';
const Types = mongoose.Schema.Types;

const Schema = new mongoose.Schema({
    book: {
        type: Types.ObjectId,
        ref: "book"
    },
    startCounter: {
        type: Types.Number,
        required: true
    },
    endCounter: {
        type: Types.Number,
        required: true
    }
});

Schema.statics = {
    collectionName: modelName,
    routeOptions: {
        associations: {
            book: {
                type: "MANY_ONE",
                model: "book"
            },
            verses: {
                type: "MANY_MANY",
                model: "verse"
            },
            sections: {
                type: "MANY_MANY",
                model: "section",
                alias: "section",
                linkingModel: "section_section"
            }
        }
    }
};

return Schema;

}

[OliS76]

I found the same issue.
Interestingly, when I refer to your example above
try a
GET /user/{secondUserId}/user

In my case, this is where I found the association but from secondUserId to secondUserId.

That looks like a bug to me.

[OliS76]

So, interesting further discovery:
It works when you add embedAssociation: true,
then it adds the association for
GET /user/{secondUserId}/user
and for
GET /user/{firstUserId}/user
to the respective association partner.

Just one note:
API-wise I would have exprected the association to be directed
I.e. only firstUserId -> secondUserId
but it generates an undirected association
firstUserId <-> secondUserId

Maybe I missed that from the documentation ;-)

[JKHeadley]

@OliS76 Thanks for the input! This will be the first issue I'll look into when I get a chance.