laravel APi resource Call to undefined method Illuminate\Database\Query\Builder::mapInto()
The problem is that you use UserResource::collection($this->user) and you have just one element not a collection so you can replace it with new UserResource($this->user) like this :
return [ 'id' => $this->id, 'title' => $this->title, 'slug' => $this->slug, 'bodys' => $this->body, 'users' => new UserResource($this->user), 'published' => $this->published, 'created_at' => $this->created_at, 'updated_at' => $this->updated_at,];
this problem is that you use UserResource::collection($this->user) its mean you are many users but and you have just one element not a collection so you can replace it with new UserResource($this->user)
In Laravel 8.5.*, you can use the static method make on the collection to get the same result. It would be like UserResource::make($this->user)