php 如何在 Laravel 中正确合并多个集合

How to properly merge multiple collections in Laravel

提问by Marcel

I want to merge multiple collections into one. I do have a solution, which is the following:

我想将多个集合合并为一个。我确实有一个解决方案，如下所示：

$allItems = $collection1->merge($collection2)
                        ->merge($collection3)
                        ->merge($collection4)
                        ->merge($collection5);

This actually does work, but I run into problems in cases where some or all of the collections contain no objects. I get an error along the lines of call to merge() on non object.

这实际上确实有效，但是在某些或所有集合不包含对象的情况下我会遇到问题。我在call to merge() on non object.

I actually tried to create an array of all of the collections, and then iterate through them, while checking their validity, but it didn't work and I feel it wasn't very elegant.

我实际上尝试创建所有集合的数组，然后遍历它们，同时检查它们的有效性，但它不起作用，我觉得它不是很优雅。

How can I elegantly iterate through this process of merging multiple collections, while taking into account that some or all of the collections might be empty or invalid? Appreciated!

如何优雅地遍历合并多个集合的过程，同时考虑到部分或全部集合可能为空或无效？赞赏！

回答by Marcel

What I ended up doing was separating each step. It was the merge chaining that was killing it, because some or all of the collections could have been invalid.

我最终做的是分离每一步。是合并链杀死了它，因为部分或全部集合可能是无效的。

$allItems = new \Illuminate\Database\Eloquent\Collection; //Create empty collection which we know has the merge() method
$allItems = $allItems->merge($collection1);
$allItems = $allItems->merge($collection2);
$allItems = $allItems->merge($collection3);
$allItems = $allItems->merge($collection4);

回答by Leonid Dashko

I had the same question, so I solved it in the following way:

我有同样的问题，所以我通过以下方式解决了它：

$clients = ClientAccount::query()->get();
$admins = AdminAccount::query()->get();

$users = collect($clients)->merge($admins)->merge($anotherCollection)->merge(...);

回答by wayne

depend on your data, if collection is actually null or your php support it you can do:

取决于您的数据，如果集合实际上为 null 或您的 php 支持它，您可以执行以下操作：

    $allItems = $collection1->merge($collection2 ?: collect())
                    ->merge($collection3 ?: collect())
                    ->merge($collection4 ?: collect())
                    ->merge($collection5 ?: collect());

or you want to do a reduce:

或者你想做一个减少：

    $allItems = collect([$collection2, $collection3, $collection4])->reduce(function($arr, $item) {
        if (empty($item) || $item->isEmpty())
            return $arr;
        return $arr->merge($item);
    }, $collection1);

or plain php reduce without overhead

或普通的 php 减少没有开销

    $allItems = array_reduce([
        $collection2,
        $collection3,
        $collection4
    ], function($arr, $item) {
        if (empty($item) || $item->isEmpty())
            return $arr;
        return $arr->merge($item);
    }, $collection1);

回答by hawx

You could also try:

你也可以试试：

$allItems = collect([
  'collection_1_key' => $collection_1,
  'collection_2_key' => $collection_2,
  'collection_3_key' => $collection_3,
  'collection_4_key' => $collection_4,
]);

回答by Aruna Perera

I used ->merge()but faced a small issue. So I'm adding this in case anyone else face the same issue. ->concat()is a better solution on database collection merging.

我用过，->merge()但遇到了一个小问题。所以我添加这个以防其他人面临同样的问题。->concat()是数据库集合合并的更好解决方案。

$allItems = new \Illuminate\Database\Eloquent\Collection; 
$allItems = $allItems->concat($collection1);
$allItems = $allItems->concat($collection2);

The reason for this is when merging they take ID of the tableas the key. So if two tables have two records with same table id ->merge()will add only one record to $allItems. But ->concat()will add two records as they should.

这样做的原因是在合并时它们以表的 ID作为键。因此，如果两个表有两个具有相同表 ID 的->merge()记录，则只会将一条记录添加到$allItems. 但是->concat()会添加两条记录。