Fix the inclusion of relations

[schtibe]

When getting a list and including data from the models in the list, only
the related data of the first model in the list was included

Explanation:
Let's assume a Model M that has a foreign key type referencing Type. Now we get a list of M which have different types and include the types (?include=type), only the Type of the first reference will be included, because of line 417.

[jerel]

@jsenecal I'm 👍 on this if you want to review and merge

[jsenecal]

Have you tried setting a path in the include parameter? Like so: include=blog.author otherwise I don't understand your issue

[schtibe]

Assuming table Person:

pk	fruit (fk to Fruit)	Person
1	1	John
2	1	Jack
3	2	Jill

and table Fruit:

pk	name
1	apple
2	banana

Now let's do GET /api/v1/person?include=fruit which is programmed to return all persons

Gives roughly following result (I wrote this from memory ):

    {
        "data": [{
                "type": "persons",
                "id": 1,
                "attributes": { "name": "John" },
                "relationships": {
                    "fruit": {
                        "data": { "type": "fruit", "id": "1" }
                    }
                }
            },
            {
                "type": "persons",
                "id": 2,
                "attributes": { "name": "Jack" },
                "relationships": {
                    "fruit": {
                        "data": { "type": "fruit", "id": "1" }
                    }
                }
            },
            {
                "type": "persons",
                "id": 3,
                "attributes": { "name": "Jill" },
                "relationships": {
                    "fruit": {
                        "data": { "type": "fruit", "id": "2" }
                    }
                }
            }
        # so far so good, now here it gets interesting
        ],
        "included": [{
            "type": "fruit",
            "id": 1,
            "attributes": {
                "name": "apple"
            }
        }]
        # banana is missing, even though the person 3 references it
    },

[jsenecal]

Ok, so I'm trying to understand your last comment @schtibe - why would /api/v1/apple return person objects ?

Anyways - I'll merge this as the change makes sense and somewhat seem to work for me too but I'll try to make tests to validate the behavior when I fix #126

[schtibe]

@jsenecal oh, sorry this is an error. It would be /api/v1/person of course.

[jerel]

@schtibe I also ran into a strange bug with included records today. Could you take a look at my PR and see if it's related to the behavior you were seeing?

Edit: mentioned the wrong person by accident.