php Laravel 5：违反完整性约束：1452 无法添加或更新子行：外键约束失败
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Laravel 5: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails
提问by LoveAndHappiness
I have a simple Article Model and a User Model.
我有一个简单的文章模型和一个用户模型。
Article "belongsTo" a User and a User "hasMany" Article.
文章“属于”一个用户和一个用户“hasMany”文章。
Therefore my article migration has a foreign key called "user_id".
因此，我的文章迁移有一个名为“user_id”的外键。
Schema::create('articles', function(Blueprint $table) {
$table->increments('id');
$table->string('title');
$table->text('body');
$table->integer('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users');
$table->timestamps();
});
Yet whenever I create an Article where I pass the "user_id" in a hidden field I get an error message.
然而，每当我创建一篇文章，在隐藏字段中传递“user_id”时，我都会收到一条错误消息。
{!! Form::open(array('route' => 'articles.store')) !!}
{!! Form::hidden('userId', $user->id) !!}
<div class="form-group">
{!! Form::label('title', 'Title') !!}
{!! Form::text('title', null, array('class' => 'form-control')) !!}
</div>
<div class="form-group">
{!! Form::label('text', 'Write your Article') !!}
{!! Form::textarea('text', null, array('class' => 'form-control')) !!}
</div>
{!! Form::submit('Create Article', array('class' => 'btn btn-default btn-success')) !!}
{!! Form::close() !!}
This is the error message. And I understand that I doesn't try to insert the value for the 'user_id' into the articles table.
这是错误信息。而且我知道我不会尝试将“user_id”的值插入到文章表中。
SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (
tags.articles, CONSTRAINTarticles_user_id_foreignFOREIGN KEY (user_id) REFERENCESusers(id)) (SQL: insert intoarticles(title,body,updated_at,created_at) values (Title, Some text, 2015-03-21 23:19:33, 2015-03-21 23:19:33))
SQLSTATE[23000]: 完整性约束违规：1452 无法添加或更新子行：外键约束失败 (
tags.articles, CONSTRAINTarticles_user_id_foreignFOREIGN KEY (user_id) REFERENCESusers(id)) (SQL: insert intoarticles(title,body,updated_at,created_at) values (Title, Some文本, 2015-03-21 23:19:33, 2015-03-21 23:19:33))
Here is my Store Method on my AriclesController:
这是我的 AriclesController 上的 Store 方法：
Article::create([
'title' => Input::get('title'),
'body' => Input::get('text'),
'user_id' => Input::get('userId')
]);
return Redirect::to('articles');
There are dozens of other open Stackoverflow Questions with a similar title, and I am searching yet unsuccessfully for the answer that fits my specific case, therefore I thank you in advance kind stranger.
还有许多其他开放的 Stackoverflow 问题具有类似的标题，我正在寻找适合我的具体情况的答案但没有成功，因此我提前感谢您的好心陌生人。
How do I save an article into my database?
如何将文章保存到我的数据库中？
回答by Adam Particka
Make sure you have user_idin the fillableproperty of your Article model.
确保您拥有文章模型user_id的fillable属性。
回答by The Sammie
I had the same problem. I added a foreign key to a table that already existed and had data and I couldn't run the migrations because it kept failing. The solution to make the migration work was to make the foreign key nullable.
我有同样的问题。我向一个已经存在并有数据的表添加了一个外键，但我无法运行迁移，因为它一直失败。使迁移工作的解决方案是使外键可以为空。
$table->integer('user_id')->nullable()->unsigned();
// then the foreign key
$table->foreign('user_id')->references('id')->on('users');
Hoping it saves someone else time in the future.
希望它在未来节省其他人的时间。
