如何使用 eloquent hasmanythrough 或 hasonethrough 连接 laravel 中的 3 个表

Question

这是我的桌子的样子

部门	课程	科目
ID	ID	ID
头	部门编号	course_id
	课程名	主题代码

在我的模型中，这是我的做法，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'
    );
}

output 当我尝试使用hasOneThrough时：

{
    "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 output 应该是这样的请帮我怎么做：

{
    "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"
    }
}

Answer 1

您的表之间的关系就像学科作为课程课程有一个部门，学科有一个部门通过课程

与您的主题的关系 Model

public function Course() {
    return $this->belongsTo(Course::class);
}
public function Department() {
    return $this->hasOneThrough(Department::class, Course::class)
}

课程关系 Model

public function Subject() {
    return $this->hasMany(Subject::class);
}
public function Department() {
    return $this->belongsTo(Department::class);
}

与您部门的关系 Model

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

有关更多信息，请参阅 laravel eloquent 关系文档https://laravel.com/docs/8.x/eloquent-relationships#has-