laravel保存一对一和一对多的关系

Question

我正在创建一个应用程序，该应用程序中有一个简单的多项选择测验功能。所以我有一个Question实体和一个Answer实体。我定义了2个关系，一对多（问题可以有很多答案）和一对一（问题可以有一个正确的答案）。以下是我迄今为止：

问题型号：

class Question extends Model 
{ 
public $table = 'question'; 

public $primaryKey = 'question_id'; 

public $fillable = ['question', 'answer_id']; 

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

public function correctanswer() 
{ 
    return $this->hasOne('App\Models\Answer'); 
} 
} 

答型号：

class Answer extends Model 
{ 
public $table = 'answer'; 

public $primaryKey = 'answer_id'; 

public $guarded = ['created_at', 'updated_at']; 

public function question() 
{ 
    return $this->belongsTo('App\Models\Question'); 
} 

public function correctquestion() 
{ 
    return $this->belongsTo('App\Models\Question'); 
} 

} 

而且在我的控制器：

$input = $request->all(); 
    $answers = $input['answer']; 
    unset($input['answer']); 

    $question = Question::create($input); 

    foreach($answers as $key=>$a){ 
     $arr['question_id'] = $question->question_id; 
     $arr['answer'] = $a; 
     $answer = new Answer($arr); 
     $question->answers()->save($answer); //save all answers - this works 
     if($key == 0){ //the first submitted answer is the correct one 
      $question->correctanswer()->save($answer); //save correct answer - this doesn't work 
     } 
    } 

我的db表的定义：

CREATE TABLE IF NOT EXISTS question (
question_id int(11) unsigned NOT NULL AUTO_INCREMENT, 
question text, 
created_at timestamp, 
updated_at timestamp, 
answer_id int(11) unsigned, 
PRIMARY KEY (question_id), 
FOREIGN KEY (answer_id) 
    REFERENCES answer(answer_id) 
    ON DELETE NO ACTION 
    ON UPDATE NO ACTION 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

CREATE TABLE IF NOT EXISTS answer (
answer_id int(11) unsigned NOT NULL AUTO_INCREMENT, 
answer text, 
created_at timestamp, 
updated_at timestamp, 
question_id int(11) unsigned, 
PRIMARY KEY (answer_id), 
FOREIGN KEY (question_id) 
    REFERENCES question(question_id) 
    ON DELETE CASCADE 
    ON UPDATE CASCADE 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci; 

问题是我的问题实体没有保存正确答案。所有的答案都在应答表中妥善保存，但我只需要做到这一点，所以我知道哪个是正确的。

任何人都可以看到我做错了什么？

在此先感谢！

Answer 1

事实证明，这是哪个实体拥有关系的问题。这是我改变，使其工作：

在我的问题型号：

public function correctanswer() 
{ 
    return $this->hasOne('App\Models\Answer'); 
} 

应该

public function correctanswer() 
{ 
    return $this->belongsTo('App\Models\Answer', 'answer_id', 'answer_id'); 
} 

在我的答案型号：

public function correctquestion() 
{ 
    return $this->belongsTo('App\Models\Question'); 
} 

应：

public function correctquestion() 
{ 
    return $this->hasOne('App\Models\Question'); 
} 

然后在我的控制，我只是改变了我如何救了正确答案：

$question = Question::create($input); 

    foreach($answers as $key=>$a){ 
     $arr['question_id'] = $question->question_id; 
     $arr['answer'] = $a; 
     $answer = new Answer($arr); 
     $question->answers()->save($answer); 
     if($key == 0){ 
      //$question->correctanswer()->save($answer); 
      $answer->correctquestion()->save($question); 
     } 
    } 

我不是Laravel的专家，所以我不知道为什么有差别。

Answer 2

尝试改变关系的定义，像这样，

class Question extends Model 
{ 
    public function answers() 
    { 
     return $this->hasMany('App\Models\Answer', 'question_id'); 
    } 

    public function correctanswer() 
    { 
     return $this->hasOne('App\Models\Answer', 'question_id'); 
    } 
} 

class Answer extends Model 
{ 
    public function question() 
    { 
     return $this->belongsTo('App\Models\Question', 'question_id'); 
    } 

    public function correctquestion() 
    { 
     return $this->belongsTo('App\Models\Question', 'question_id'); 
    } 
} 

由于您的主键没有被命名id，你需要指定要使用的自定义键。