Laravel获得带有多个标签的帖子

Question

I'm working with a laravel belongsToMany relationship between Post and Tag .

What I'm trying to do is get all Post s where it has multiple tags.

I've tried all sorts of eloquent queries, but I can't get it at all.

Currently I can get an array of post_id 's and tag_id 's, as shown below, but there has to be an easier way to do this.

if (Request::has('tags')) {
    $tags = Tag::find(explode(',', Request::get('tags')));
}else{
    $tags = null;
}
// Get all posts tagged with the tags
$jobs = \DB::table('post_tag');
foreach ($tags as $tag) {
    $posts = $posts->orwhere('tag_id', $tag->id);
}
dd($posts->get());

This dumps an array of all posts that have any of the ID's, but I need to get an array of post_id s where it contains all tag_id s.

Thanks in advance!

Answer 1

It would be a good idea to use whereHas() on the Post model to eager load the tags and get only the Post s which have at least one of those tags.

$posts = Post::whereHas('tags', function($q) use ($tags)
{
    $q->whereIn('id', $tags);
})->get();

Here, $tags would just be an array of tag id's. $posts would be a Collection of Post s. To get the array of id's from it, you can simply do this...

$ids = $posts->lists('id'); 

Or instead of calling get() originally, use ...->lists('id')

If you are looking for only those Post s which contain all of the tags, you want to pass some additional parameters to the whereHas function.

$posts = Post::whereHas('tags', function($q) use ($tags)
{
    $q->whereIn('id', $tags);
}, '=', count($tags))->get();

What will happen is it will only grab posts that have a number of tags attached equal to the count of the tags in the tags array.

If you use this approach, be sure your pivot table is managed correctly in that it is not possible to attach a certain tag to a certain model more than once.