Laravel Eloquent nested relations returns data only on the first element

Question

Intro

Im havning some trubble getting the data on all the related elements. Im using Laravel as a REST backend service, exposing Json to the front-end javascript application.

Data structure

Consider I have the following tables:

+----------------+ +----------------+ +-------------+
|topics          | |posts           | |users        |
+----------------+ +----------------+ +-------------+
|id: int         | |id: int         | |id: int      |
|title: varchar  | |content: varchar| |name: varchar|
|content: varchar| |user_id: int    | +-------------+
|user_id: int    | |topic_id: int   |
+----------------+ +----------------+ 

A topic has 0 to many posts, and it has an author (user)

A post has one author (user)

UML: http://i58.servimg.com/u/f58/11/26/57/95/intrep10.png

Laravel Models

class User extends Eloquent {
    protected $table = 'users';

    public function topics() {
        reutrn $this->hasMany('Topic');
    }

    public function posts() {
        reutrn $this->hasMany('Post');
    }
}

class Topic extends Eloquent {
    protected $table = 'topics';

    public function posts() {
            return $this->hasMany('Post');
    }

    public function author() {
         return $this->hasOne('User', 'id');
    }
}

class Post extends Eloquent {
    protected $table = 'posts';

    public function topic() {
        return $this->belongsTo('Topic');
    }

    public function author() {
        return $this->hasOne('User', 'id');
    }
}

Controller

return Topic::where('id', '=', $topicId)
    ->with('author', 'posts.author')
    ->get();

Output

[{
    id: 1,
    title: "My Topic",
    content: "With opinions about the darkside",
    user_id: 1,
    created_at: "2014-03-06",
    updated_at: "2014-03-06",
    author: {
        id: 1,
        name: "JamesBond",
        created_at: "2014-03-06",
        updated_at: "2014-03-06",
    },
    posts: [{
        id: 1,
        content: "Reply 1 on topic 1",
        user_id: 1,
        created_at: "2014-03-06",
        updated_at: "2014-03-06",
        author: {
            id: 1,
            name: "JamesBond",
            created_at: "2014-03-06",
            updated_at: "2014-03-06",
        },
    },
    {
        id: 2,
        content: "Reply 2 on topic 1",
        user_id: 1,
        created_at: "2014-03-06",
        updated_at: "2014-03-06",
        author: null,
    }]
}]

Question

As you can see of the jsoncode, both the posts are created by the same user (with id 1), but only the first has the author object on it. Any pointers on how to figure out my problem would be perfect.

Disclaimer

This is a striped down version of my project, as I dont want to spam the question with information. If I lack serten elements to the question, I will be happy to supply it.

Solution

My model mapping was off.

public function author() {
    return $this->belongsTo('User', 'user_id', 'id');
}

makes sure that its the user_id its looking for in the posts table, up against the id column in the users table

SELECT * FROM users WHERE id = posts.user_id;

Answer 1

In your Topic model the relationship for the author should be

class Topic extends Eloquent {

    //...

    public function author() {
        return $this->belongsTo('User');
    }
}

Same goes to your Post model:

class Post extends Eloquent {

    // ...

    public function author() {
        return $this->belongsTo('User');
    }
}

It's because, in both tables topics and posts you have user_id and the user_id relates to the users table, so, think this way, each user_id in your topics and posts table belongs to user table where the corresponding field is id in the users table. In this case, both topics and posts tables are child of users table.

Answer 2

I think you are mixing your relationships. Should it not be:

A Post belongs to a User

A Post belongs to a Topic

A User has many Post

A Topic has many Post

Table Fields

Users: id, name

Posts: id, user_id, topic_id, content

Topic: id, title, content

Models

class User extends Eloquent {
    protected $table = 'users';

    public function posts() {
        reutrn $this->hasMany('Post');
    }
}

class Topic extends Eloquent {
    protected $table = 'topics';

    public function posts() {
        return $this->hasMany('Post');
    }

}

class Post extends Eloquent {
    protected $table = 'posts';

    public function topic() {
        return $this->belongsTo('Topic');
    }

    public function author() {
        return $this->belongsTo('User', 'id');
    }
}

To get posts with author and topic:

return Post::where('topic_id', '>=', $topicId)
    ->with('topic', 'author')
    ->get();