Laravel：如何建立关系，我该使用哪种关系？

Question

I have the database structure that have a classes table, a users table and users_classes table that matches the other two, because a user can belong to multiple classes. I have a problem now. I have code like this:

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\DB;

class Classes extends Model
{
    protected $table = 'classes';   

    public function students()
    {

    }             
}

And I want to be able to access the students of the class by typing $class = Classes::find(1) and then $class->students to access the students. How do I define the relationship without using the query builder? I want to use eloquent. Im a noobie in Laravel pls dont downvote.

Answer 1

You use a belongsToMany relation.

If your users_classes table has the fields user_id and class_id you can do the following:

public function students()
{
    return $this->belongsToMany(Student::class, 'users_classes', 'class_id', 'user_id');
}