php - Display parent id with many-to-many relationship

Question

I have a relationship many-to-many. I need to fetch all tags with parent id. For example it can look like this:

[
   { article_id: 1, id: 1, name: "tag 1" },
   { article_id: 1, id, 2, name: "tag 2" },
   { article_id: 2, id: 1, name: "tag 1" }
]

Look that tag 1 is two times for two articles. Propably I can make loop inside loop but it doesn't look proffesional. Could you show me the best solution of this problem?

@Edit: I created this code:

public function articles(){
    $article = [];
    $allArticles = Articles::all();
    foreach($allArticles as $key => $a){
        $obj = new stdClass();
        foreach($a->tags as $t){
            $obj->article_id = $a->id;
            $obj->name = $t->name;
            array_push($article, $obj);
        }

    }


    return json_encode($article);
}

But it doesn't work like I want. It display only one tag for one article, not all. Any idea?

question from:https://stackoverflow.com/questions/65860731/display-parent-id-with-many-to-many-relationship

Answer 1

Don't quite understand what you are trying to achieve via the code snippet you have provided. However, as per the opening line of your question if you want to retrieve all tags with associated articles' ids then you can try the below

$tags = Tag::with('articles')
    ->get()
    ->map(function($tag) {
        $tag->articleIds = $tag->articles->pluck('id');
        unset($tag->articles);
        return $tag;
    });

This will give you an output like

[
   { id: 1, name: "tag 1", articleIds: [1,2] },
   { id, 2, name: "tag 2", articleIds: [1] },
]

If you want it other way around i.e. get the article with associated tags

$articles = Article::with('tags:id,name')
    ->get()
    ->map(function($article) {
        $object = new StdClass;
        $object->article_id = $article->id;
        $object->tags = $article->tags;
        return $object;
    });

Which will give you an output like

[
   { article_id: 1, tags: [{id: 1, name: "tag 1" }, {id, 2, name: "tag 2"}] },
   { article_id: 2, tags: [{id: 1, name: "tag 1" }]},
]