完整性約束違規：1452無法添加或更新子行：

Question

我試圖插入值到我的評論表中，我收到錯誤。它說我不能添加或更新子行，我不知道這意味着什麼。

我的架構看起來像這樣

-- ---------------------------- 
-- Table structure for `comments` 
-- ---------------------------- 
DROP TABLE IF EXISTS `comments`; 
CREATE TABLE `comments` (
    `id` varchar(36) NOT NULL, 
    `project_id` varchar(36) NOT NULL, 
    `user_id` varchar(36) NOT NULL, 
    `task_id` varchar(36) NOT NULL, 
    `data_type_id` varchar(36) NOT NULL, 
    `data_path` varchar(255) DEFAULT NULL, 
    `message` longtext, 
    `created` datetime DEFAULT NULL, 
    `modified` datetime DEFAULT NULL, 
    PRIMARY KEY (`id`), 
    KEY `fk_comments_users` (`user_id`), 
    KEY `fk_comments_projects1` (`project_id`), 
    KEY `fk_comments_data_types1` (`data_type_id`), 
    CONSTRAINT `fk_comments_data_types1` FOREIGN KEY (`data_type_id`) REFERENCES `data_types` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION, 
    CONSTRAINT `fk_comments_projects1` FOREIGN KEY (`project_id`) REFERENCES `projects` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION, 
    CONSTRAINT `fk_comments_users` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION 
) ENGINE=InnoDB DEFAULT CHARSET=utf32; 

-- ---------------------------- 
-- Records of comments 
-- ---------------------------- 

-- ---------------------------- 
-- Table structure for `projects` 
-- ---------------------------- 
DROP TABLE IF EXISTS `projects`; 
CREATE TABLE `projects` (
    `id` varchar(36) NOT NULL, 
    `user_id` varchar(36) NOT NULL, 
    `title` varchar(45) DEFAULT NULL, 
    `description` longtext, 
    `created` datetime DEFAULT NULL, 
    `modified` datetime DEFAULT NULL, 
    PRIMARY KEY (`id`), 
    KEY `fk_projects_users1` (`user_id`), 
    CONSTRAINT `fk_projects_users1` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION 
) ENGINE=InnoDB DEFAULT CHARSET=utf32; 

-- ---------------------------- 
-- Records of projects 
-- ---------------------------- 
INSERT INTO `projects` VALUES ('50dcbc72-3410-4596-8b71-0e80ae7aaee3', '50dcbc5c-d684-40bf-9715-0becae7aaee3', 'Brand New Project', 'This is a brand new project', '2012-12-27 15:24:02', '2012-12-27 15:24:02'); 

，我試圖做MySQL的聲明看起來是這樣的

INSERT INTO `anthonyl_fbpj`.`comments` (`project_id`, `user_id`, `task_id`, `data_type_id`, `message`, `modified`, `created`, `id`) 
VALUES ('50dc845a-83e4-4db3-8705-5432ae7aaee3', '50dcbc5c-d684-40bf-9715-0becae7aaee3', '1', '50d32e5c-abdc-491a-a0ef-25d84e9f49a8', 'this is a test', '2012-12-27 19:20:46', '2012-12-27 19:20:46', '50dcf3ee-8bf4-4685-aa45-4eb4ae7aaee3') 

我的錯誤看起來像這樣

SQLSTATE [23000]：完整性約束違規：1452無法添加或 更新子行：外部關鍵約束失敗 （anthonyl_fbpj。 comments，約束fk_comments_projects1 外鍵（project_id）參考文獻projects（id）ON DELETE NO 行動UPDATE NO ACTION）

Answer 1

它只是簡單的說就是在表comments要插入的project_id列中的值不存在於表projects。請記住，表comments上的列project_id的值取決於表Projects上的ID的值。

您爲插入列project_id的值50dc845a-83e4-4db3-8705-5432ae7aaee3在表projects上不存在。

Answer 2

確保您在Comment模型的fillable屬性中有project_id。

我有同樣的問題，這就是原因。

Answer 3

還要確保您添加的外鍵與原始列的類型相同，如果您參考的列不是相同的類型，它也會失敗。

Answer 4

如果有人使用Laravel並且出現此問題。我也收到了這個問題，問題在於我在數據透視表中插入id（即外鍵）的順序。

要具體，在下面的例子爲多對多的關係：

wordtokens < - > wordtoken_wordchunk < - > wordchunks

// wordtoken_wordchunk table 
Schema::create('wordtoken_wordchunk', function(Blueprint $table) { 
     $table->integer('wordtoken_id')->unsigned(); 
     $table->integer('wordchunk_id')->unsigned(); 

     $table->foreign('wordtoken_id')->references('id')->on('word_tokens')->onDelete('cascade'); 
     $table->foreign('wordchunk_id')->references('id')->on('wordchunks')->onDelete('cascade'); 

     $table->primary(['wordtoken_id', 'wordchunk_id']); 
    }); 

// wordchunks table 
Schema::create('wordchunks', function (Blueprint $table) { 
     $table->increments('id'); 
     $table->timestamps(); 
     $table->string('text'); 
    }); 

// wordtokens table 
Schema::create('word_tokens', function (Blueprint $table) { 
     $table->increments('id'); 
     $table->string('text'); 
}); 

現在我的模型看起來像如下：

class WordToken extends Model 
{ 
    public function wordchunks() { 
     return $this->belongsToMany('App\Wordchunk'); 
    } 
} 

class Wordchunk extends Model 
{ 

    public function wordTokens() { 
     return $this->belongsToMany('App\WordToken', 'wordtoken_wordchunk', 'wordchunk_id', 'wordtoken_id'); 
    } 
} 

我通過在Wordchunk模型中交換'wordchunk_id'和'wordtoken_id'的順序來解決問題。

代碼完成，這是我堅持的車型：

private function persistChunks($chunks) { 
    foreach ($chunks as $chunk) { 
     $model = new Wordchunk(); 
     $model->text = implode(' ', array_map(function($token) {return $token->text;}, $chunk)); 
     $tokenIds = array_map(function($token) {return $token->id;}, $chunk); 
     $model->save(); 
     $model->wordTokens()->attach($tokenIds); 
    } 
}