Laravel雄辩的关系(包含上一篇文章的类别)

Question

我有多个类别，每个类别都有许多帖子，我想为每个类别获取4个最后的帖子，我使用以下代码：

$catsWitposts= $this->categories->with(['posts' => function($query){
                        $query->where('show', '=', 1);
                        $query->limit(4);
                        $query->orderBy('created_at','desc');
                    }])->get();

但是这段代码显示了所有类别的4个帖子

查询结果应显示：

cat-01
 post-01
 post-02
 post-03
 post-04
cat-02
 post-05
 post-06
 post-07
 post-08
cat-03
 post-09
 post-10
 post-11
 post-12
....

谢谢

Answer 1

一个例子

//Grab all categories
$categories = Category::all();

//This array will contain our result
$latest_posts_by_category = [];

//We use this array to save each post id that we have already collected
//in order to avoid to put it twice.
//Remember that some posts may belongs to many categories.
$ids = [];

//For each category we grab the latest post with the latest first associated category
//(Note that you can collect all associated categories if you want by remove the first() in the closure)
foreach($categories as $category){
    $post = Post::with(['categories' => function($query){
        $query->latest()->first();
    }])
    ->online() //You may have a custom method like this.
    ->latest()
    ->whereHas('categories', function($query) use($category) {
        $query->whereName($category->name);
    })->take(1)->first();

    //We take in account the fact that
    //some posts may belongs to many categories.
    //Obviously, we don't want to put it twice
    if(!in_array($post->id, $ids)){
        $latest_posts_by_category[] = $post;
        $ids[] = $post->id;
    }
}

//You can now use $latest_posts_by_category as you want