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

【问题标题】：how to join 3 tables in laravel using eloquent hasmanythrough or hasonethrough如何使用 eloquent hasmanythrough 或 hasonethrough 在 laravel 中加入 3 个表
【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": "smith@gmail.com",
    "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": "smith@gmail.com",
    "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。

标签： javascript php laravel model relationship

【解决方案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

【讨论】：