从laravel中的数据库获取所有帖子及其评论

Question

I've got a system in which there are users who create posts and they can comment on posts as well.

Here are migrations:

users table

public function up()
{
    Schema::create('users', function (Blueprint $table) {
    $table->increments('id');
    $table->string('name');
    $table->string('gender')->default('Male');
    $table->string('email')->unique();
    $table->string('city')->default('Peshawar');
    $table->string('avatar')->default('user.png');
    $table->string('password');
    $table->rememberToken();
    $table->timestamps();
});
}

posts table

    public function up()
{
    Schema::create('posts', function (Blueprint $table) {


        $table->bigIncrements('p_id');
        $table->text('description');
        $table->integer('user_id');   // this should be user id nothing else
        $table->timestamps();

    });
}

comments table

    public function up()
{
    Schema::create('comments', function (Blueprint $table) {
        $table->bigIncrements('id');
        $table->integer('user_id'); // who has done comment
        $table->integer('post_id');  // on which post comment has been done
        $table->text('body');
        $table->timestamps();
    });
}

Models

User Model

class User extends Authenticatable{
use Notifiable;

// custom function used for relationshisp
// user can have many posts

public function posts(){
    return $this->hasMany('App\Post');
}

// user can have many comments as well

public function comments(){
    return $this->hasMany('App\Comment');
}

}

Post Model

class Post extends Model{
   // posts belongs to one user
   public function user(){
    return $this->belongsTo('App\User');
  }


   public function comments(){
    return $this->hasMany('App\Comment');
   } 

 }

Comment Model

class Comment extends Model

{

// doing this we could insert data into comment table
protected $fillable =['user_id','post_id','body'];
// we need two(2) relations here
// relation of comment with post

// relation of comment with user

// 1. comment belongs to one post

public function post(){
    return $this->belongsTo('App\Post');
}

// 2. comment belongs to a user as well

public function user(){
    return $this->belongsTo('App\User');
}

}

route

Route::get('/home', 'HomeController@index')->name('home');

Here is the index method in HomeController

public function index(){
    $posts = Post::with('comments')->get();
    // $comments = Comment::all();

    return view('home')->with( array('posts'=>$posts ) );
}

Problem

So when I visit /home I want to get all posts with their comments .

As you can see I've retrieved posts with their comment like this:

$posts = Post::with('comments')->get();

And then I'm passing it to home.blade.php . Here is what I'm doing at home.blade.php to achieve this task.

View /home.blade.php

@foreach($posts as $post)

     <h4 class="media-heading">{{$post->user->name}}</h4>
     <small>{{$post->created_at}}</small>

     <p>{{$post->description}}</p>

     <!-- trying to retrieve comments with each post -->

             @if (count($post->comments))
                  @foreach($post->commnents as $comment)
                      <small>$comment->body</small>
                   @endforeach
             @else 
                  No comments Found
             @endif 




 @endforeach

It gives me this error

Undefined variable: post (View: F:\\application\\resources\\views\\home.blade.php)

Keeping in mind those models and their relationships with each other, am I doing it in the wrong way to retrieve comments for each post? If so, how can I get all the posts with their comments and when there are no comments it should say no comments found .

Here is what the result return by dd($posts) dd($posts) returning this , have a look at the comments field, that is empty.

The network tab is showing the following Please help, Thanks to everyone.

Answer 1

its probably because of this..

public function up()
{
    Schema::create('posts', function (Blueprint $table) {


        $table->bigIncrements('p_id'); <---
        $table->text('description');
        $table->integer('user_id');   // this should be user id nothing else
        $table->timestamps();

    });
}

any reason why you are using p_id instead of id? relations work so that id of post is matched to the post_id in the comments table.. if you using this u have to specify this custom key when you are creating the relationship..

check out https://laravel.com/docs/5.8/eloquent-relationships#defining-relationships

Answer 2

Try passing your post custom key as third argument to the relation:

Comment Model

public function post(){
    return $this->belongsTo('App\Post', 'post_id', 'p_id');
}

---

Maybe a better option will be, change the key of the table posts to 'id' to agree with the conventions of Laravel. Create a new migration and run it.

Schema::table('posts', function (Blueprint $table) {
    $table->renameColumn('p_id', 'id');
});

---

Another option would be, creating the foreign key constraints, to force referential integrity at the database level:

posts table

public function up()
{
    Schema::create('posts', function (Blueprint $table) {
        $table->bigIncrements('p_id');
        $table->text('description');
        $table->integer('user_id')->unsigned();
        $table->timestamps();

        $table->foreign('user_id')->references('id')->on('users');
    });
}

comments table

public function up()
{
    Schema::create('comments', function (Blueprint $table) {
        $table->bigIncrements('id');
        $table->integer('user_id')->unsigned(); 
        $table->integer('post_id')->unsigned();  
        $table->text('body');
        $table->timestamps();

        $table->foreign('user_id')->references('id')->on('users');
        $table->foreign('post_id')->references('p_id')->on('posts');
    });
}

You will have to rollback and re-run the migrations (you will lose the data saved in DB).