如何访问 Laravel 集合中的第 n 个项目？
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How to access the nth item in a Laravel collection?
提问by D?uris
I guess I am breaking all the rules by deliberately making a duplicate question...
我想我故意提出重复的问题违反了所有规则......
The other questionhas an accepted answer. It obviously solved the askers problem, but it did not answer the title question.
在其他问题有一个公认的答案。它显然解决了提问者的问题，但它没有回答标题问题。
Let's start from the beginning - the first()method is implemented approximately like this:
让我们从头开始 - 该first()方法的实现大致如下：
foreach ($collection as $item)
return $item;
It is obviously more robust than taking $collection[0]or using other suggested methods.
它显然比采用$collection[0]或使用其他建议的方法更可靠。
There might be no item with index 0or index 15even if there are 20 items in the collection. To illustrate the problem, let's take this collection out of the docs:
即使集合中有 20 个项目，也可能没有带有索引0或索引的15项目。为了说明这个问题，让我们从文档中取出这个集合：
$collection = collect([
['product_id' => 'prod-100', 'name' => 'desk'],
['product_id' => 'prod-200', 'name' => 'chair'],
]);
$keyed = $collection->keyBy('product_id');
Now, do we have any reliable (and preferably concise) way to access nth item of $keyed?
现在，我们是否有任何可靠的（最好是简洁的）方式来访问第 n 项$keyed？
My own suggestion would be to do:
我自己的建议是这样做：
$nth = $keyed->take($n)->last();
But this will give the wrong item ($keyed->last()) whenever $n > $keyed->count(). How can we get the nth item if it exists and nullif it doesn't just like first()behaves?
但这会在$keyed->last()任何时候给出错误的项目 ( ) $n > $keyed->count()。如果第 n 个项目存在并且null它不只是first()行为，我们如何获得第 n 个项目？
Edit
编辑
To clarify, let's consider this collection:
为了澄清，让我们考虑这个集合：
$col = collect([
2 => 'a',
5 => 'b',
6 => 'c',
7 => 'd']);
First item is $col->first(). How to get the second?
第一项是$col->first()。如何获得第二个？
$col->nth(3)should return 'c'(or 'c'if 0-based, but that would be inconsistent with first()). $col[3]wouldn't work, it would just return an error.
$col->nth(3)应该返回'c'（或者'c'如果是基于 0 的，但这将与 不一致first()）。$col[3]不起作用，它只会返回错误。
$col->nth(7)should return nullbecause there is no seventh item, there are only four of them. $col[7]wouldn't work, it would just return 'd'.
$col->nth(7)应该返回，null因为没有第七项，只有四项。$col[7]不起作用，它只会返回'd'。
You could rephrase the question as "How to get nth item in the foreach order?" if it's more clear for some.
您可以将问题重新表述为“如何获取 foreach 订单中的第 n 个项目？” 如果对某些人来说更清楚。
回答by Alexey Mezenin
回答by Amit Gupta
回答by Muhammad Syauqy
Based on Alexey's answer, you can create a macro in AppServiceProvider (add it inside register method):
根据 Alexey 的回答，您可以在 AppServiceProvider 中创建一个宏（将其添加到 register 方法中）：
use Illuminate\Support\Collection;
Collection::macro('getNth', function ($n) {
return $this->slice($n, 1)->first();
});
and then, you can use this throughout your application:
然后，您可以在整个应用程序中使用它：
$collection = ['apple', 'orange'];
$collection->getNth(0) // returns 'apple'
$collection->getNth(1) // returns 'orange'
$collection->getNth(2) // returns null
$collection->getNth(3) // returns null
回答by tylik
Maybe not the best option, but, you can get item from array inside collection
也许不是最好的选择，但是，您可以从集合内的数组中获取项目
$collection->all()[0]
