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When calling CollegeMajor::with('majors')->get(), I would like to apply the following raw sql query: TRIM(TRAILING SUBSTRING_INDEX(parent_id, ':', -1) FROM parent_id) to the parent_id column. The values in parent_id are stored as 1:1234, 1:3121, 1:1332 etc... and so therefore I'd like to strip everything after the colon. The primary key for CollegeMajor is id and those values are integers like 1. I get the error below because Laravel believes the raw query is the name of the column. How do I tell Laravel to apply that sql query to project_id column when executing the relationship?

CollegeMajor.php

class CollegeMajor extends Model {
   public function majors() {
     return $this->hasMany('App\Models\CollegeMajor', \DB::raw(TRIM(TRAILING SUBSTRING_INDEX(parent_id, ':', -1) FROM parent_id)))
                  ->where('entity', 'major');
   }
}

Error

Unknown column 'college_major.TRIM(TRAILING SUBSTRING_INDEX(parent_id, ':', -1) FROM parent_id)' in 'where clause' (SQL: select * from `college_major` where `entity` = major and `college_major`.`TRIM(TRAILING SUBSTRING_INDEX(parent_id, ':', -1) FROM parent_id)` in (1, 2, 3, 4, 5, 6, 7, 8))

college_majors table

id      name             entity   parent_id
1   College of Art       college     1234
2   College of Business  college     4567
3   Art History          major     1:1234
4   Asian Art            major     1:1234
5   Accounting           major     2:4567
6   Marketing            major     2:4567

How to make it return?

[
  id: 1,
  name: 'College of Art',
  entity: 'college',
  parent_id: 1234,
  majors: [
    {
      id: 3,
      name: 'Art History',
      entity: 'major',
      parent_id: '1:1234'
    },
    {
      id: 4,
      name: 'Asian Art',
      entity: 'major',
      parent_id: '1:1234'
    }

  ]
  ....
]
4

1 回答 1

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第二个参数hasMany()是外键。所以你不能在那里定义你的查询。如下定义您的关系。

public function majors() { 
     return $this->hasMany('App\Models\CollegeMajor'); 
}

然后，当您查询使用原始表达式时。

CollegeMajor::with('majors')
     ->select(DB::raw('TRIM(TRAILING SUBSTRING_INDEX(parent_id, ":", -1) FROM parent_id))')
->where('entity', 'major')->get();

尚未测试。在我的手机上 ：）

于 2017-01-30T03:18:40.073 回答