在Laravel4中有很多通过数据透视表

Question

我正在尝试与Eloquent建立一个hasManyTrough关系,但目前还不清楚它是如何从文档中运行的.

表:

users
   - id
   - firstname
   - ...etc

accounts
   - id
   - user_id
   - username
   - ...etc

roles
   - id
   - permissions

account_role
   - id
   - account_id
   - role_id

楷模

<?php
class User extends Eloquent {

    public function account()
    {
        return $this->hasOne('Account');
    }

    // This is what I'm trying to achieve
    public function roles()
    {
        return $this->hasManyThrough('Role', 'Account');
    }
}

class Role extends Eloquent {

    public function accounts()
    {
        return $this->belongsToMany('Account')->withTimestamps();
    }
}

class Account extends Eloquent {

    public function user()
    {
        return $this->belongsTo('User');
    }
}

错误和问题 我得到的错误是: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'roles.account_id' in 'on clause'

我知道我可以做点什么$user->account->roles,但我希望能做到$user->roles.如何正确设置？

Answer 1

最后我通过执行以下操作解决了这个问题:

class User extends Eloquent {

    /**
     * @return \Illuminate\Database\Eloquent\Relations\BelongsToMany
     */
    public function roles()
    {
        return $this->account->belongsToMany('Navicula\Entities\Role');
    }
}

我怀疑这不会急于加载帐户,导致大量的查询开销.但是,当我尝试使用User::with('roles')->limit(100)->get();并记录查询时,运行了以下查询:

SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL LIMIT 100
SELECT * FROM `accounts` WHERE `accounts`.`deleted_at` IS NULL LIMIT 1
SELECT `roles`.*, `account_role`.`account_id` as `pivot_account_id`, `account_role`.`role_id` as `pivot_role_id` FROM `roles` inner join `account_role` on `roles`.`id` = `account_role`.`role_id` WHERE `account_role`.`account_id` in ('1', '2', '3', '4', '5', '6', '7', '8', '9', '10', '11', '12', '13', '14', '15', '16', '17', '19', '20', '21', '22', '23', '24', '25', '26', '27', '28', '29', '30', '31', '32', '33', '34', '35', '36', '37', '38', '39', '40', '41', '42', '43', '44', '45', '46', '47', '48', '49', '50', '51', '52', '53', '54', '55', '56', '57', '58', '60', '61', '62', '63', '64', '65', '67', '68', '70', '71', '72', '73', '74', '75', '78', '79', '80', '81', '82', '83', '84', '85', '86', '87', '88', '89', '90', '91', '92', '93', '94', '95', '96', '97', '98', '99', '100', '101', '102', '103', '104', '105', '106')

这正是我们想要的.谢谢泰勒;-)