Laravel 4渴望与关系有关的加载问题

Question

I have two tables, items and users. A User can have multiple Items and an Item can be owned by one User.

My two tables have many fields but are linked by:

Item
----
ownerID

User
----
id

These are the fields that link the two tables together and they are set in my database with a foreign key.

Here is a shortened version of the two models:

class Item extends Eloquent {
    public function owner()
    {   
        return $this->belongsTo('User','id');
    }
}

class User extends Eloquent implements UserInterface, RemindableInterface {
    public function items()
    {
        return $this->hasMany('Item', 'ownerID');
    }
}

So, I want to get all of my Items and eager load the owner. This is my code in my Controller:

class ItemsController extends BaseController {
    public function all(){
        $items = Item::with('owner')->get();
        return $items;
    }
}

(I am returning $items so I can debug the output)

However, this is what I get as my output:

[
    {
        "active":"1",
        "categoryID":"1",
        "created_at":"0000-00-00 00:00:00",
        "description":"Just a test item",
        "endDate":"2014-03-01 21:46:07",
        "id":"32",
        "name":"Test Item",
        "owner":null,
        "ownerID":"1",
        "section":"0",
        "updated_at":"0000-00-00 00:00:00"
    }
]

I don't understand why owner is null? User ID 1 exists in my database so why is it null?

Answer 1

According to your function in Item

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

It indicates that, the foreign key in the items table is id which is being used for relationship with users table but you have used ownerId as the foreign key in the items table which is the primary key of users table.

So, it should be

public function owner()
{   
    // This model (child) with a local-key/field ownerId
    // in it's corresponding table(items) belongs to/relates to the
    // user model (parent) with primary-key id in corresponding (users) table
    return $this->belongsTo('User','ownerID');
}

While using belongsTo/reverse the second argument passed to the function is the referencing key (child-key/local-key) in the current table and here, items is the current table, which has the referencing key ownerId as it's local-key which relates to the id field of users table.

Answer 2

Try this

class Item extends Eloquent {
    public function owner()
    {   
        return $this->belongsTo('User','ownerID');
    }
}