如何使用 eloquent hasmanythrough 或 hasonethrough 在 laravel 中加入 3 个表

Posted 2023-03-15

【中文标题】如何使用 eloquent hasmanythrough 或 hasonethrough 在 laravel 中加入 3 个表

【英文标题】：how to join 3 tables in laravel using eloquent hasmanythrough or hasonethrough

【发布时间】：2022-01-10 20:28:06

【问题描述】：

这是我的桌子的样子

departments	course	subjects
id	id	id
head	department_id	course_id
	course_name	subject_code

在我的模型中，我就是这样做的，但似乎不起作用，我不知道为什么：

public function departments()

    return $this->hasOneThrough(
        subjectlist::class,
        department::class,
        'id',
        'course_id',
        'id',
        'id'
    );

我尝试使用hasOneThrough时的输出：

    "id": 1,
    "department_name": "Business",
    "head": "John smith",
    "email": "[e-mail]",
    "contact_number": "09300282103",
    "created_at": null,
    "updated_at": null,
    "subject_list": 
        "id": 1,
        "course_id": 1,
        "subject_code": "Math1",
        "description": "math test",
        "year_type": 1,
        "price": "200.00",
        "units": "5.00",
        "created_at": null,
        "updated_at": null,
        "laravel_through_key": 1
    

我不希望输出应该是这样的，请帮助我如何做到这一点：

    "id": 1,
    "department_name": "Business",
    "head": "John smith",
    "email": "[e-mail]",
    "contact_number": "09300282103",
    "created_at": null,
    "updated_at": null,
    "subject_list": 
        "id": 1,
        "course_id": 1,
        "subject_code": "Math1",
        "description": "math test",
        "year_type": 1,
        "price": "200.00",
        "units": "5.00",
        "created_at": null,
        "updated_at": null,
        "laravel_through_key": 1
    ,
    "department": 
        "id": 1,
        "department_name": "ComputerScience"
    

【问题讨论】：

请出示您的型号查询码。

【参考方案1】：

你的表之间的关系就像 作为课程的主题 课程有一个部门 和科目通过课程有一个部门

主题模型的关系

public function Course() 
    return $this->belongsTo(Course::class);

public function Department() 
    return $this->hasOneThrough(Department::class, Course::class)

课程模型的关系

public function Subject() 
    return $this->hasMany(Subject::class);

public function Department() 
    return $this->belongsTo(Department::class);

与您的部门模型的关系

public function Course() 
    return $this->hasMany(Course::class);

更多信息请参考 laravel eloquent 关系文档 https://laravel.com/docs/8.x/eloquent-relationships#has-one-through