Laravel 5.7多个外键引用相同的表主键

Question

I have a table Task where it has creatorID and assignedTo . Both of them are foreign keys to my User table's primary key u_id . I'm trying to display the names of the creatorID and assignedTo but it is not working, it gave an error Trying to get property 'name' of non-object . Anyone able to spot whats wrong with my code? I'm opened to any suggestions or modifications to my models/tables thank you.

Task Table(Migration)

Schema::create('tasks', function (Blueprint $table) {
    $table->increments('t_id');
    $table->string('t_name');
    $table->date('start_date');
    $table->date('end_date');
    $table->string('status');
    $table->unsignedInteger('creatorID');
    $table->unsignedInteger('assignedTo')->nullable();
    $table->unsignedInteger('p_id');
    $table->foreign('creatorID')->references('u_id')->on('users');
    $table->foreign('assignedTo')->references('u_id')->on('users');
    $table->foreign('p_id')->references('p_id')->on('projects');
    $table->string('priority');
    $table->timestamps();
});

User Table(Migration)

Schema::create('users', function (Blueprint $table) {
    $table->increments('u_id');
    $table->string('name');
    $table->string('email')->unique();
    $table->string('password');
    $table->rememberToken();
    $table->string('status');
    $table->string('picture');
    $table->timestamps();
});

Task Model

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

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

User Model

public function tasks(){
    return $this->hasMany('App\Task','u_id');
}

public function assignedTo(){
    return $this->hasMany('App\Task','assignedTo');
}

Query

$ActiveTasks = Task::where('p_id',$projectID)->where('status','active')->get();

Blade File

@foreach($ActiveTasks as $task)
    <p>{{$task->assignedTo->name}}</p>   <<< NOT WORKING
@endforeach

Answer 1

You may need to update the assignedTo relationship in your Task model so that it knows to reference u_id instead of id :

public function assignedTo()
{
    return $this->belongsTo(\App\User::class, 'assignedTo', 'u_id');
}

According to the docs:

If your parent model does not use id as its primary key, or you wish to join the child model to a different column, you may pass a third argument to the belongsTo method specifying your parent table's custom key

https://laravel.com/docs/5.7/eloquent-relationships#defining-relationships

You should also check the tasks table to see if the assignedTo column is null for any of the saved records. Since you have the nullable attribute set, any records that had a null value in assignedTo would also produce the Trying to get property 'name' of non-object error when the relationship was accessed. If that's the case, you can define the relationship using the withDefault() method:

The belongsTo relationship allows you to define a default model that will be returned if the given relationship is null. This pattern is often referred to as the Null Object pattern and can help remove conditional checks in your code

https://laravel.com/docs/5.7/eloquent-relationships#inserting-and-updating-related-models