laravel 5.2一對多關系問題

Question

我在Laravel 5.2模型中設置了以下一對多關系。 在Workout子模型中使用group_id屬性引用了WorkoutGroup父模型。 每個WorkoutGroup對象可以由多個Workout對象引用，因此是一對多關系。

問題是我無法使用體育鍛煉方法從WorkoutGroup中檢索Workout子代...

這是子對象

// Workout class
<?php
namespace App;

use Illuminate\Database\Eloquent\Model;

class Workout extends Model
{
    protected $table = 'c_workouts';

    protected $fillable = [
        "group_id", "name", "set_time", "created_at", "updated_at"
    ];

    public function group() {
        return $this->belongsTo(WorkoutGroup::class, 'group_id');
    }

}

這是父對象

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class WorkoutGroup extends Model
{
    protected $table = 'c_workouts_groups';

    protected $fillable = [
        "name"
    ];

    public function workouts() {
        return $this->hasMany(Workout::class, 'group_id');
    }
}

遷移文件

use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateCWorkoutsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('c_workouts_groups', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name', "16");
        });

        DB::table("c_workouts_groups")->insert([
            ["name" => "crunches"],
        ]);

        Schema::create('c_workouts', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('group_id', false, true)->length(10)->nullable();
            $table->foreign('group_id')
                ->references('id')->on('c_workouts_groups')
                ->onDelete('cascade');
            $table->integer('set_time');
            $table->string('name', "128");
            $table->timestamps();
        });

        DB::table("c_workouts")->insert([
            ["name" => "bicicleta", "set_time" => 1, "group_id" => null],
            ["name" => "quadriceps", "set_time" => 0, "group_id" => null],
            ["name" => "femorales", "set_time" => 0, "group_id" => null],
            ["name" => "press lombo", "set_time" => 0, "group_id" => null],
            ["name" => "press pectoral", "set_time" => 0, "group_id" => null],
            ["name" => "polita alta dorsal", "set_time" => 0, "group_id" => null],
            ["name" => "biceps", "set_time" => 0, "group_id" => null],
            ["name" => "triceps", "set_time" => 0, "group_id" => null],
            ["name" => "dorsal", "set_time" => 0, "group_id" => 1],
            ["name" => "frontal medio alto", "set_time" => 0, "group_id" => 1],
            ["name" => "frontal medio bajo", "set_time" => 0, "group_id" => 1],
            ["name" => "frontal bajo", "set_time" => 0, "group_id" => 1],
            ["name" => "trotadora", "set_time" => 1, "group_id" => null]
        ]);
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        DB::statement('SET FOREIGN_KEY_CHECKS = 0');
        Schema::drop('c_workouts_groups');
        Schema::drop('c_workouts');
        DB::statement('SET FOREIGN_KEY_CHECKS = 1');
    }
}

有人弄錯了嗎？

Answer 1

如果執行\\App\\WorkoutGroup::find(1)->workouts您的代碼應該可以正常工作。

當您使用find() ，您沒有集合，您有一個雄辯的模型，因此使用first()不會產生期望的效果。

並且在獲取關系時，不需要作為函數調用->workouts()如果這樣做，則必須完成最終的查詢，調用get方法->workouts()->get() 。

Answer 2

您需要使用此：

$test = \\App\\WorkoutGroup::find(1)->workouts延遲加載

或渴望加載（通常更好） \\App\\WorkoutGroup::with('workouts')->find(1)