php - laravel Eloquent 关系问题

Question

我有点困惑，我需要一些帮助，因为我是 laravel 的新手!我有3张 table !问题、类别和主题

一个问题有一个类别和一个主题一个主题有很多类别一个类别属于一个主题

我被要求做的是什么时候我会添加一个问题，我只从列表中选择一个类别，它将与她的相应主题一起添加到问题表中!!我希望我能很好地解释我的问题 :)

the category migration 
Schema::create('category', function(Blueprint $table)
    {
        $table->increments('categoryId');
        $table->string('categoryName');
        $table->integer('themeId')->unsigned();
        $table->foreign('themeId')->references('themeId')->on('theme');
    });
the theme migration 
Schema::create('theme', function(Blueprint $table)
    {
        $table->increments('themeId');
        $table->string('themeName');
    });

the questio migration i didn't make relation since i didn't find a way to do it 
Schema::create('question', function(Blueprint $table)
        {
        $table->increments('questionId');
        $table->string('question', 200);
        $table->string('rightAnswer', 50);
        $table->string('explanation', 500);
        $table->string('wrongAnswer1', 50);
        $table->string('wrongAnswer2', 50);
        $table->string('wrongAnswer3', 50);
        $table->string('theme');
        $table->string('category');
        $table->integer('difficulty');
        $table->timestamps();
        });

Answer 1

主题模型

class Theme extends Eloquent 
{   
    protected $primaryKey = 'themeId';
    protected $guarded = array();
    public function category()
    {
        return $this->hasMany('Category');
    }
}

类别模型

class Category extends Eloquent 
{
    protected $primaryKey = 'categoryId';

    protected $guarded = array();

    public function theme()
    {
        return $this->belongsTo('Theme');
    }
}

问题模型

class Question extends Eloquent 
{
    protected $primaryKey = 'questionId';

    protected $guarded = array();

    public function category()
    {
        return $this->belongsTo('Category');
    }
}