并且belongsTo是一个one-to-many，而不是many-to-many。
关于你的问题，你可以在任何定义它的地方访问关系，但除非你定义它，否则不能访问逆关系！
例如，如果您有教师和学生模型

教师模型

use Illuminate\Database\Eloquent\Relations\HasMany;

class Teacher extends Model {

    public function students(): HasMany {
        return $this->hasMany(Student::class);
    }
}

学生模型

use Illuminate\Database\Eloquent\Relations\BelongsTo;

class Student extends Model {

    //Relation below not define.
    /* public function teacher(): BelongsTo {
        return $this->belongsTo(Teacher::class);
    } */
}

//each line below works fine, you can perform relationship related query 
$teacher->students()->create([...]); // create students relation
$teacher->students; //lazy load students relation
Teacher::with('students')->paginate(); //eager load students relation

//each line below will throw 500 error as Inverse relation is not define 
$student->teacher()->create([...]); // create teacher relation
$student->teacher; //lazy load teacher relation
Student::with('teacher')->paginate(); //eager load teacher relation

应用程序实际上并没有发生什么变化，只是如果您要访问透视表，您将无法从它调用任何关系。

如果你正在创建透视表，你应该创建一个belongsToMany关系，它为你提供sync（），attach（）方法。否则你可以简单地创建hasMany关系。你实际上在尝试做什么？