Question

我有点困惑，我需要一些帮助，因为我是laravel的新人！我有3张桌子！问题，类别和主题

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

我要做的是当我添加一个问题时我只从列表中选择一个类别，它将在问题表中添加她的对应主题!!我希望我解释好我的问题:)

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');
    }
}

Answer 2

您不会在迁移中建立Eloquent关系。迁移仅用于创建数据库表结构。相反，Eloquent中的关系在您制作的模型中定义：

// Theme Model
public function categories()
{
    return $this->hasMany('Category');
}

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

public function questions()
{
    return $this->hasMany('Question');
}

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

模型中的这些方法在Eloquent中定义关系，让你做这样的事情：

// Given an instance of a theme
foreach($theme->categories as $category)
    // ...

// Given an instance of a question
echo $question->category->theme->themeName;

话虽如此，鉴于您的表结构，上述方法无法正常工作。 Eloquent还依赖于约定，并且惯例是外键应以特定方式命名，即theme_id和category_id（vs themeId，就像在类别表中一样）。您可以使用以下格式按documentation覆盖此内容：

return $this->belongsTo('Theme', 'themeId');

虽然你最好坚持常规。此约定还声明每个表的主键应命名为id。

对于您的问题表，您可以创建与该类别的关系，就像您对主题和类别之间的关系所做的那样：在问题表中添加一个引用类别ID的列：

// Your migration:
$table->integer('category_id');
// Add a foreign key as well if you wish, though it is not 
// required for the relationship in Eloquent

然后在您的问题模型中放置我在上面概述的category方法。就这么简单。

laravel雄辩的关系问题

2 个答案: