Laravel：查找数据透视表记录是否存在
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Laravel: find if a pivot table record exists
提问by datavoredan
I have two models which are joined by a pivot table, Userand Task.
我有两个由数据透视表连接的模型，User以及Task.
I have a user_idand a task_id.
我有一个user_id和一个task_id。
What is the neatest way to check whether a record exists for this combination of user and task?
检查用户和任务的这种组合是否存在记录的最简洁方法是什么？
回答by patricus
You have a couple options depending on your situation.
根据您的情况，您有几种选择。
If you already have a Userinstance and you want to see if it has a task with a certain id, you can do:
如果您已经有一个User实例，并且想查看它是否有具有特定 id 的任务，您可以执行以下操作：
$user = User::find(1);
$hasTask = $user->tasks()->where('id', $taskId)->exists();
You can reverse this if you have the Taskinstance and want to check for a user:
如果您拥有Task实例并想要检查用户，则可以反转此操作：
$task = Task::find(1);
$hasUser = $task->users()->where('id', $userId)->exists();
If you just have the ids, without an instance of each, you could do the following:
如果您只有 id，而没有每个实例，则可以执行以下操作：
$hasPivot = User::where('id', $userId)->whereHas('tasks', function ($q) use ($taskId) {
$q->where('id', $taskId);
})
->exists();
回答by Yurich
may be you search this?
你可能在搜索这个吗？
$users = User::has('task')->get();
回答by Prafulla Kumar Sahu
You can also try this, this is working in Laravel 5.7
你也可以试试这个，这在 Laravel 5.7 中有效
$user = User::find(1);
$hasTask = $user->tasks->contains($taskId);
But the better way will be using whereHas.
但更好的方法是使用 whereHas。
$hasTask = $user->tasks()->where('tasks.id', $taskId)->exists();
回答by Marcus Christiansen
Easiest to read for me is:
对我来说最容易阅读的是：
$user->tasks()->exists();
回答by spencerfeng
You can use the code below:
您可以使用以下代码：
$user = User::find(1);
$hasTask = $user->tasks()->where('task_id', $taskId)->exists();
