Eloquent Injected Multiple Model Relationships - laravel

Question

So I learned in JeffreyWay's screencasts that I can use Eloquent to get the associated id from a model injected to another model.
I'm following his series about Laravel 5.4.
Here, I have a one-to-many relationships of user to posts.
App/Post
public function user()
{
return $this->belongsTo(User::class);
}
In my User Model, I have a publish method where the Post Model is injected. The publish method is used to create a post entry into the database.
App/User
public function posts()
{
return $this->hasMany(Post::class);
}
public function publish(Post $post)
{
$this->posts()->save($post);
}
I then have a store method in my PostsController that calls the publish method inside my User Model.
PostsController
class PostsController extends Controller
{
public function __construct()
{
$this->middleware('auth')->except(['index', 'show']);
}
public function store()
{
auth()->user()->publish(
new Post(request(['title', 'body']))
);
}
}
When the publish method is called, the injected Post class automatically sets the user_id to the save method.
My question is, how do I make a relationship like this in a situation where for every posts, there are comments. These comments are associated to the Post and the User that created the comment.
In short, I should have both user_id and post_id when I call the addComment method.

Answer 1

User Model:
public function posts(){
return $this->hasMany(Post::class);
}
public function comments(){
return $this->hasMany(Comments::class);
}
Posts Model
public function user(){
return $this->belongsTo(User::class);
}
public function comments(){
return $this->hasMany(Comments::class);
}
Comments Model
public function post(){
return $this->belongsTo(Post::class);
}
public function user(){
return $this->belongsTo(User::class);
}
Example Problems:
1) Get user comments:
Solution: auth()->user()->comments()->get(); <- collection of user
comments .
2) Get user from the given comment:
Solution: Comment::find($someCommentId)->user()->first()->name; <-
User name from a specific comment.
3) Get all comments for a specific post .
Solution: Post::first()->comments()->get(); or eager load
Post::with('comments')->first(); <- A collection that contains post
information within it u can find a collection of comments for that
post.
4) Load user when loading a comment:
Solution: Comment::with('user')->first(); <- single collection
containing a collection with user info and comment info.
5) Load a specific user post and comments for that post at the same time:
Solution: User::with('posts.comments')->first(); <- Contains a
collection with user info and collection of all user posts with each
post containing comments.

Answer 2

In your question you wrote:
In short, I should have both user_id and post_id when I call the addComment method.
Which is absolutely correct and no problem. You don't have to set these properties through a method like $user->posts()->save($post) - this is just a convenience method that does the job for you (see save($model) and related setForeignAttributesForCreate($model) in the framework code; these methods just set the foreign key property for you).
In fact, the following three ways to create a new post are interchangeable:
// what you did
$user->posts->save(
new Post([
'title' => 'Hello',
'body' => 'World!',
])
);
// equivalent
Post::create([
'user_id' => \Auth::user()->id, // or \Auth::id()
'title' => 'Hello',
'body' => 'World!',
]);
// also equivalent
$post = new Post([
'user_id' => \Auth::user()->id, // or \Auth::id()
'title' => 'Hello',
'body' => 'World!',
]);
$post->save();
When storing a new comment, you will most likely have a controller like this, because a comment always belongs to a post and you therefore will need a reference of the post:
class CommentsController extends Controller
{
public function __construct()
{
$this->middleware('auth')->except(['index', 'show']);
}
public function store(Post $post)
{
$comment = new Comment(request(['body']));
$comment->user_id = \Auth::user()->id;
$comment->post_id = $post->id;
$comment->save();
}
}
You could also abbreviate it and write:
Comment::create(
array_merge(request(['body']), ['user_id' => \Auth::id(), 'post_id' => $post->id])
);