How to return name of table of grade when save like json? - laravel-5.8

Question

I have two tables, users and grades.
users table
public function up()
{
Schema::create('users', function (Blueprint $table) {
$table->bigIncrements('id');
$table->string('name');
$table->string('email')->unique();
$table->timestamp('email_verified_at')->nullable();
$table->string('password');
$table->string('first_name')->nullable();
$table->string('last_name')->nullable();
$table->string('grade_id')->nullable();
}
}
grades table
public function up()
{
Schema::create('grades', function (Blueprint $table) {
$table->bigIncrements('id');
$table->string('name');
$table->timestamps();
});
}
I save id of grade with json_encode,
I save in field like this
$user->grade_id = json_encode($request->input('grade_id'));
I want to return the grade name but I did not solve my problem
Controller
public function index()
{
$grades = Grade::all();
return view('index', compact('grades');
}
User.php
public function grade()
{
return $this->belongsTo(Grade::class);
}
index.blade.php
#if(isset(auth()->user()->grade_id) && !empty(auth()->user()->grade_id))
<?php
$grade = json_decode(auth()->user()->grade->name, true);
#foreach($grade as $key=>$item)
<li>
<div class="grade">{{ $grade[$key] }}</div>
</li>
#endforeach
?>
#endif
I get this errpr
Trying to get property of non-object

Answer 1

Bad answer
You save an array of ids in the users table. Then when you do $grade = json_decode(auth()->user()->grade->name) you get something you don't want to have. Indeed, the value of auth()->user()->grade is ["8", "8"], this is not a grade model. Now you should understand why this $grade = json_decode(auth()->user()->grade->name) fail: you're trying to get name property of a non object (as user()->grade is just an array).
To solve it badly (read the next part of my answer) you can just do this in your controller (you shouldn't do any <?php ?> in your view files):
public function index()
{
$grades_ids = json_decode(auth()->user()->grade); // ["8", "8"]
$grades = Grade::whereIn('id', $grades_ids)->get(); // Eloquent collection
return view('index', compact('grades');
}
And use it in your view:
#if($grades->count())
<ul>
#foreach($grades as $grade)
<li>
<div class="grade">{{ $grade->id }}</div>
</li>
#endforeach
</ul>
#endif
Good answer
Here you have a typical many to many relationships. A grade can have multiple users, and a user can have multiple grades. Then you should think of using a pivot table rather than a encoding several grade_id in json.
Create a users table:
public function up()
{
Schema::create('users', function (Blueprint $table) {
$table->bigIncrements('id');
$table->string('name');
$table->string('email')->unique();
$table->timestamp('email_verified_at')->nullable();
$table->string('password');
$table->string('first_name')->nullable();
$table->string('last_name')->nullable();
}
}
Then you create your grades table:
public function up()
{
Schema::create('grades', function (Blueprint $table) {
$table->bigIncrements('id');
$table->string('name');
$table->timestamps();
});
}
Then you create the new user_grade_table:
public function up()
{
Schema::create('user_grade', function (Blueprint $table) {
$table->primary(['user_id', 'grade_id']);
$table->unsignedBigInteger('user_id');
$table->unsignedBigInteger('grade_id');
$table->timestamps();
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
$table->foreign('grade_id')->references('id')->on('users')->onDelete('cascade');
});
}
public function down()
{
Schema::table('user_grade', function (Blueprint $table) {
$table->dropPrimary('user_grade_user_id_grade_id_primary');
$table->dropForeign('user_grade_user_id_foreign');
$table->dropForeign('user_grade_grade_id_foreign');
});
Schema::dropIfExists('user_grade');
}
Don't forget to run the migrations. When this is done, you have to update your models, adding the belongs to many on both models.
User model
public function grades()
{
return $this->belongsToMany(Grade::class, 'user_grade', 'user_id', 'grade_id');
}
Same for grade model:
public function users()
{
return $this->belongsToMany(User::class, 'user_grade', 'grade_id', 'user_id');
}
Finally you can use it in your blade file:
#if($grades = auth()->user()->grades)
<ul>
#foreach($grades as $grade)
<li>
<div class="grade">{{ $grade->name }}</div>
</li>
#endforeach
</ul>
#endif