php Laravel Eloquent：如何对相关模型的结果进行排序？
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Laravel Eloquent: How to order results of related models?
提问by Debiprasad
I have a model called Schooland it has many Students.
我有一个名为School的模型，它有很多学生。
Here is the code in my model:
这是我模型中的代码：
public function students()
{
return $this->hasMany('Student');
}
I am getting all the students with this code in my controller:
我让所有学生都在我的控制器中使用此代码：
$school = School::find($schoolId);
and in the view:
并在视图中：
@foreach ($school->students as $student)
Now I want to order the Studentsby some field in the studentstable. How can I do that?
现在我想按表中的某个字段对学生进行排序students。我怎样才能做到这一点？
回答by Jarek Tkaczyk
You have a few ways of achieving this:
您有几种方法可以实现这一点：
// when eager loading
$school = School::with(['students' => function ($q) {
$q->orderBy('whateverField', 'asc/desc');
}])->find($schoolId);
// when lazy loading
$school = School::find($schoolId);
$school->load(['students' => function ($q) {
$q->orderBy('whateverField', 'asc/desc');
}]);
// or on the collection
$school = School::find($schoolId);
// asc
$school->students->sortBy('whateverProperty');
// desc
$school->students->sortByDesc('whateverProperty');
// or querying students directly
$students = Student::whereHas('school', function ($q) use ($schoolId) {
$q->where('id', $schoolId);
})->orderBy('whateverField')->get();
回答by fico7489
you can add orderBy to your relation, so the only thing you need to change is
您可以将 orderBy 添加到您的关系中，因此您唯一需要更改的是
public function students()
{
return $this->hasMany('Student');
}
to
到
public function students()
{
return $this->hasMany('Student')->orderBy('id', 'desc');
}
回答by Jason
To answer the original question, the studentsdynamic property can also be accessed as a relationship method.
为了回答最初的问题，students动态属性也可以作为一种关系方法来访问。
So you have this to fetch all students:
所以你有这个来获取所有学生：
$students = $school->students;
Now as a relationship method, this is equivalent:
现在作为一种关系方法，这是等效的：
$students = $school->students()->get();
Given this, you can now add in some ordering:
鉴于此，您现在可以添加一些排序：
$students = $school->students()->orderBy('students.last_name')->get();
Since eloquent will be performing a join, make sure to include the table name when referencing the column to order by.
由于 eloquent 将执行连接，因此在引用要排序的列时确保包含表名。
You can also add this to your studentsmethod if you want to set a default order that $school->studentswill always return. Check out the documentation for hasMany()to see how this works.
students如果您想设置一个$school->students总是返回的默认顺序，您也可以将它添加到您的方法中。查看文档hasMany()以了解其工作原理。
回答by Madhavi Khatal
For Many to one relation I found one answer on:
对于多对一的关系，我找到了一个答案：
https://laracasts.com/discuss/channels/eloquent/order-by-on-relationship
https://laracasts.com/discuss/channels/eloquent/order-by-on-relationship
$order = 'desc';
$users = User::join('roles', 'users.role_id', '=', 'roles.id')
->orderBy('roles.label', $order)
->select('users.*')
->paginate(10);
this can save day... of anyone
这可以挽救任何人的一天......
回答by FaridLU
You can use this like this:
你可以这样使用它：
$students = $school->students()->orderBy('id', 'desc');
You can also use
你也可以使用
$students = $school->students()->orderBy('id', 'desc')->paginate(10);
