Laravel 4 Eloquent选择

Question

I have 3 tables

--- Posts (all the posts) rows = id, title, content

--- Boards (all the boards) rows = id, title

--- board_post (the link between boards and posts: many <-> many) rows = board_id, post_id

2 Eloquent classes named board and post

now I would love to select all the posts from a board, based on board_post

I was thinking in the way of: Posts::whereIn('id', $board->post_ids())

how would I be able to do this, that first off that if I do Board::find(1)->post_ids I get all the post id's of that board

And then how wuld I be able to get all the post opbjects from that?

greetings Glenn

Answer 1

In Board model make sure you define belongsToMany relationship

public function posts()
{
    return $this->belongsToMany('Post', 'board_post');
}

Now you should be able to do this:

Board::find({id})->posts

Forther reading material: http://laravel.com/docs/eloquent#relationships

Answer 2

Why are you using a many-to-many relationship for Posts and Boards? It would most likely be a one-to-many relationship: A Board may have several posts, but a Post should only belong to one board (this would simplify your database structure to remove the board_post table).

You would then do:

Inside of Board class:

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

Then, Board::find(1)->posts would get you all of the posts for that board (use posts, not posts()).

---

To do it with your current database setup, use belongsToMany instead:

public function posts() {
  return $this->belongsToMany('Post', 'board_post');
} 

If you want to load a Board WITH all of it's posts (eager-loading) use this:

Board::with('posts')->find(1)

Otherwise, just to get the posts for a particular board, use:

Board::find(1)->posts