Laravel 4.1处理多对多关系

Question

I have a Post model with the following function:

public function tags() {

    return $this->belongsToMany('Tag', 'refs', 'post', 'tag');

}

And a Tag model with a similar function:

public function posts() {

    return $this->belongsToMany('Post', 'refs', 'tag', 'post');

}

Now I'm outputting my tags as checkboxes in a foreach loop. What I'm then interested in doing is checking the boxes corresponding to tags that are related to the Post model I'm working with in the given view, but intuition did not solve the issue for me, and I don't know enough technical jargon to formulate a proper search query for an answer on Google.

EDIT:

In case of relevance this is my foreach loop:

    @foreach($tags as $tag)
        <tr>
        <td><label for="{{ $tag->id }}">{{ $tag->title }}</label></td>
        <td><input type="checkbox" value="{{ $tag->id }}" name="tags[]" id="{{ $tag->id }}" /></td>
        </tr>
    @endforeach

Which works perfectly. I just need to figure out what my if-statement should be for outputting the following at the end of my input tag in the correct loops.

checked="checked"

Answer 1

Sounds like you want something like this:

<input type="checkbox" value="{{ $tag->id }}" name="tags[]" id="{{ $tag->id }}" @if ($post->tags->contains($tag->id)) checked="checked" @endif />

So, basically, if the Post 's collection of Tag s contains the Tag 's id, the checkbox will be checked.