Laravel 5有很多透视透视表

Question

我试图创建一个关系，通过一个名为年级的模型访问一个名为注释的表，通过年级中的学生加载

年级模型和学生模型都属于其他模型

根据我的理解，不可能访问需要透视表的hasManyThrough关系（注释没有年级标识符，只有学生标识符）

class Grade extends Model{
    public function comments(){
        return $this->hasManyThrough("App\Comment","App\Student");
    }
}

我为Laravel 4@HasManyThrough找到了这些函数，它们具有一对多关系，但它给了我一个错误类“App\illumb\Database\Eloquent\Relations\HasMany”

我对命名空间没有很好的理解，也不知道我应该在Laravel 5的位置上做什么。

public function getCommentsAttribute()
{
    if ( ! array_key_exists('comments', $this->relations)) $this->loadComments();

    return $this->getRelation('comments');
}

protected function loadComments()
{
    $comments = Comment::join('grade_student', 'comments.student_id', '=', 'grade_student.student_id')
        ->where('grade_student.grade_id', $this->getKey())
        ->distinct()
        ->get(['comments.*','grade_id']);

    $hasMany = new Illuminate\Database\Eloquent\Relations\HasMany(Translation::query(), $this, 'grade_id', 'id');

    $hasMany->matchMany(array($this), $comments, 'comments');

    return $this;
}

注释表

    Schema::create('comments', function (Blueprint $table) {
        $table->increments('id');
        $table->timestamps();
        $table->integer('student_id')->unsigned();
        $table->integer('domain_id')->unsigned();
        $table->integer('teacher_id')->unsigned();
        $table->text('comment');

        $table->foreign('student_id')->references('id')->on('students') ->onDelete('cascade');
        $table->foreign('domain_id') ->references('id')->on('domains')->onDelete('cascade');
        $table->foreign('teacher_id')->references('id')->on('teachers')->onDelete('cascade');
    });

我的学生桌

Schema::create('students', function (Blueprint $table) {
    $table->increments('id');
    $table->timestamps();
    $table->string('unique_identifier');
    $table->string('first_name');
    $table->string('last_name');
    $table->enum('gender',array('m','f'));
});

我的成绩表

Schema::create('grades', function (Blueprint $table) {
    $table->increments('id');
    $table->timestamps();
    $table->string('name',20);
    $table->integer('school_id')->unsigned();
    $table->integer('level_id')->unsigned();
    $table->foreign('school_id')->references('id')->on('schools')->onDelete('cascade');
    $table->foreign('level_id')->references('id')->on('classes_levels')->onDelete('cascade');
});

我的透视表

Schema::create('grade_student', function (Blueprint $table) {
    $table->engine = 'InnoDB';
    $table->increments('id');
    $table->timestamps();
    $table->integer('grade_id')->unsigned();
    $table->integer('student_id')->unsigned();
    $table->integer('school_id')->unsigned();
    $table->integer('year');

    $table->foreign('grade_id')->references('id')->on('grades')->onDelete('cascade');
    $table->foreign('student_id') ->references('id')->on('students')->onDelete('cascade');
    $table->foreign('school_id')->references('id')->on('schools') ->onDelete('cascade');
});

Answer 1

看看这里。

目前，Laravel5.3不支持使用透视表的hasManyThrough。只要用另一种方法。

作为一种替代方式：
只考虑这些模型及其关系：

A <=> B with pivot table A_B
B <=> C with pivot table B_C

现在，您可以创建一个称为a_C的透视视图：

SELECT A_id, C_id FROM A_B
INNER JOIN B_C on A_B.B_id = B_C.B_id
GROUP BY A_id, C_id

我想你能猜到我的把戏。
是的，忘记hasManyPass。现在，您可以使用A。