Php App\Tasks:：first（）->；项目；在artisan tinker中，无论发生什么情况，都会返回null：(

tinker中的以下代码返回空值，但它应该返回第一个任务链接到的项目

App\Task::first()->projects;

已经尝试在迁移中重命名方法名、列名，尝试退出tinker并重新登录

项目迁移

public function up()
    {
        Schema::create('projects', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->text('title');
            $table->string('description');
            $table->timestamps();
        });
    }

public function up()
    {
        Schema::create('tasks', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->unsignedInteger('project_id');
            $table->string('description');
            $table->boolean('completed')->default(false);
            $table->timestamps();
        });
    }

任务迁移

public function up()
    {
        Schema::create('projects', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->text('title');
            $table->string('description');
            $table->timestamps();
        });
    }

public function up()
    {
        Schema::create('tasks', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->unsignedInteger('project_id');
            $table->string('description');
            $table->boolean('completed')->default(false);
            $table->timestamps();
        });
    }

Project.php

use App\Task;

class Project extends Model
{
    protected $fillable = ['title','description'];

    public function tasks(){
      return $this->hasMany(Task::class);
    }
}

Task.php

use App\Project;

class Task extends Model
{
  protected $fillable = [
    'completed'
  ];
  public function projects(){
    return $this->belongsTo(Project::class);
  }
}

如果有人能检查一下这段代码，告诉我我在哪里犯了任何常规的愚蠢的错误（因为我是新来的路由模型绑定），那将是非常有帮助的！

• 任务属于项目，因此将项目重命名为project，因为它是单数。如果保留项目，请提供列名作为第二个参数：

• 您的列类型不同，对于项目id，您使用大整数；对于引用，您使用整数，因此：

应该是这样的：

$table->unsignedBigInteger('project_id');

// also good to make the relationship on the Database level:

$table->foreign('project_id')->references('id')->on('projects')->onDelete('cascade');