在 Laravel 5.1 中为 foreach() 提供的参数无效
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Invalid argument supplied for foreach() in Laravel 5.1
提问by zlotte
Everything was working fine and I don't know what happened. I'm getting this error:
一切正常，我不知道发生了什么。我收到此错误：
Invalid argument supplied for foreach().
为 foreach() 提供的参数无效。
I'm trying to get tags that are attached to post like this @foreach($post->tags as $tag)If I do var_dumpthen it says string(0)""if I do this with @if(is_array($post->tags))- no error and no tags. I don't know where the problem is because the categories are made in the same principle and they are working fine.
我正在尝试获取像这样附加到帖子的标签@foreach($post->tags as $tag)如果我这样做了，var_dump那么它会说string(0)""我是否这样做@if(is_array($post->tags))- 没有错误，也没有标签。我不知道问题出在哪里，因为类别是按照相同的原则制作的，并且它们工作正常。
This is Post.php model code:
这是 Post.php 模型代码：
public function tags()
{
return $this->belongsToMany('App\Tag');
}
public function getTagListAttribute()
{
return $this->tags->lists('id')->all();
}
This is Tag.php model code:
这是 Tag.php 模型代码：
public function post()
{
return $this->belongsToMany('App\Post');
}
回答by cre8
There is a simple call you can use for this case:
对于这种情况，您可以使用一个简单的调用：
@forelse($users as $user)
<li>{{ $user->name }}</li>
@empty
<p>No users</p>
@endforelse
Please check the official documentation before you give inefficient answers.
在您给出低效的答案之前，请检查官方文档。
回答by P??
If there are no tags then $post->tagsis empty and therefor
@foreach($post->tags as $tag)will throw an error.
如果没有标签，$post->tags则为空，因此
@foreach($post->tags as $tag)将引发错误。
You can check with @if(!empty($post->tags)):before the foreachif there are tags for this post or not to avoid a error message.
您可以@if(!empty($post->tags)):在foreach此帖子是否有标签之前检查，以避免出现错误消息。
If there should be tags for this post but there aren't any then your $post->tagsis not filled with data correctly.
如果这篇文章应该有标签但没有标签，那么你的$post->tags数据没有正确填充。
回答by Dzung Cao
when your array is empty, contains no element, foreachwill throw that exception. For safety you can use normal for(....)instead.
当您的数组为空，不包含任何元素时，foreach将抛出该异常。为了安全起见，您可以使用 normal for(....)代替。
