Laravel eloquent 预加载两个数据透视表

Question

我正在尝试加载一个通过组拼接的属性和另一个 table 具有额外相关枢轴的属性。这是 tables:

Categories
--------------------
id

Attributes
--------------------
id
attribute_set_id


Attribute_Groups
----------------------------
id


Categories_Attribute_Groups
-----------------------------
category_id
attribute_group_id


Categories_Additional_Attributes
-----------------------------
category_id
attribute_id


Class Category extends eloquent
{

    // how to achieve this
    public function attributes()
    {
        // all attributes that can be eager load
    }
}

如何获取类别模型中的所有属性并能够预先加载它们？

Answer 1

在类别模型中，您可以将 2 个关系定义为 belongsToMany 与属性和属性组

Class Category extends eloquent
{

    public function attributes()
    {
        return $this->belongsToMany(Attribute::class, 'Categories_Additional_Attributes', 'category_id');
    }

    public function attribute_groups()
    {
        return $this->belongsToMany(AttributeGroups::class, 'Categories_Attribute_Groups', 'category_id');
    }
}

现在您可以像

Category::with(['attributes', 'attribute_groups'])->get();

对于双向映射，您可以将它们定义为

Class Attribute extends eloquent
{

    public function categories()
    {
        return $this->belongsToMany(Category::class, 'Categories_Additional_Attributes', 'attribute_id');
    }
}

Class AttributeGroups extends eloquent
{

    public function categories()
    {
        return $this->belongsToMany(Category::class, 'Categories_Attribute_Groups', 'attribute_group_id');
    }
}

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