Eloquent：集合

简介

Eloquent 返回的所有多结果集都是 Illuminate\Database\Eloquent\Collection 对象的实例，

默认情况下 Eloquent 返回的都是一个 Illuminate\Database\Eloquent\Collection 对象的实例，包括通过 get 方法检索或通过访问关联关系获取到的结果。Eloquent 的集合对象继承了 Laravel 的 集合基类，因此它自然也继承了数十种能优雅地处理 Eloquent 模型底层数组的方法。

当然，所有的集合都可以作为迭代器，可以就像简单的 PHP 数组一样来遍历它们：

$users = App\User::where('active', 1)->get();

foreach ($users as $user) {
    echo $user->name;
}

然而，集合比数组更加强大，它通过更直观的接口暴露出可链式调用的 map/reduce 等操作。举个例子，我们要删除模型中所有未激活的并收集剩余用户的名字：

$users = App\User::where('active', 1)->get();

$names = $users->reject(function ($user) {
    return $user->active === false;
})
->map(function ($user) {
    return $user->name;
});

{note} 大多数 Eloquent 集合方法会返回新的 Eloquent 集合实例，但是 pluck, keys, zip, collapse, flatten 和 flip 方法除外，它们会返回 集合基类 实例。同样，如果 map 操作返回的集合不包含任何 Eloquent 模型，那么它会被自动转换成集合基类。

可用的方法

集合基类

所有 Eloquent 集合都继承了基础的 Laravel 集合 对象。因此，它们也继承了所有集合基类提供的强大的方法：

[all](/docs//collections#method-all) [average](/docs//collections#method-average) [avg](/docs//collections#method-avg) [chunk](/docs//collections#method-chunk) [collapse](/docs//collections#method-collapse) [combine](/docs//collections#method-combine) [contains](/docs//collections#method-contains) [containsStrict](/docs//collections#method-containsstrict) [count](/docs//collections#method-count) [diff](/docs//collections#method-diff) [diffKeys](/docs//collections#method-diffkeys) [each](/docs//collections#method-each) [every](/docs//collections#method-every) [except](/docs//collections#method-except) [filter](/docs//collections#method-filter) [first](/docs//collections#method-first) [flatMap](/docs//collections#method-flatmap) [flatten](/docs//collections#method-flatten) [flip](/docs//collections#method-flip) [forget](/docs//collections#method-forget) [forPage](/docs//collections#method-forpage) [get](/docs//collections#method-get) [groupBy](/docs//collections#method-groupby) [has](/docs//collections#method-has) [implode](/docs//collections#method-implode) [intersect](/docs//collections#method-intersect) [isEmpty](/docs//collections#method-isempty) [isNotEmpty](/docs//collections#method-isnotempty) [keyBy](/docs//collections#method-keyby) [keys](/docs//collections#method-keys) [last](/docs//collections#method-last) [map](/docs//collections#method-map) [mapWithKeys](/docs//collections#method-mapwithkeys) [max](/docs//collections#method-max) [median](/docs//collections#method-median) [merge](/docs//collections#method-merge) [min](/docs//collections#method-min) [mode](/docs//collections#method-mode) [nth](/docs//collections#method-nth) [only](/docs//collections#method-only) [partition](/docs//collections#method-partition) [pipe](/docs//collections#method-pipe) [pluck](/docs//collections#method-pluck) [pop](/docs//collections#method-pop) [prepend](/docs//collections#method-prepend) [pull](/docs//collections#method-pull) [push](/docs//collections#method-push) [put](/docs//collections#method-put) [random](/docs//collections#method-random) [reduce](/docs//collections#method-reduce) [reject](/docs//collections#method-reject) [reverse](/docs//collections#method-reverse) [search](/docs//collections#method-search) [shift](/docs//collections#method-shift) [shuffle](/docs//collections#method-shuffle) [slice](/docs//collections#method-slice) [sort](/docs//collections#method-sort) [sortBy](/docs//collections#method-sortby) [sortByDesc](/docs//collections#method-sortbydesc) [splice](/docs//collections#method-splice) [split](/docs//collections#method-split) [sum](/docs//collections#method-sum) [take](/docs//collections#method-take) [tap](/docs//collections#method-tap) [toArray](/docs//collections#method-toarray) [toJson](/docs//collections#method-tojson) [transform](/docs//collections#method-transform) [union](/docs//collections#method-union) [unique](/docs//collections#method-unique) [uniqueStrict](/docs//collections#method-uniquestrict) [values](/docs//collections#method-values) [when](/docs//collections#method-when) [where](/docs//collections#method-where) [whereStrict](/docs//collections#method-wherestrict) [whereIn](/docs//collections#method-wherein) [whereInStrict](/docs//collections#method-whereinstrict) [whereNotIn](/docs//collections#method-wherenotin) [whereNotInStrict](/docs//collections#method-wherenotinstrict) [zip](/docs//collections#method-zip)

自定义集合

如果你需要在自己的扩展方法中使用自定义的 Collection 对象，可以在你自己的模型中重写 newCollection 方法：

<?php

namespace App;

use App\CustomCollection;
use Illuminate\Database\Eloquent\Model;

class User extends Model
{
    /**
     * 创建一个新的 Eloquent 集合实例对象。
     *
     * @param  array  $models
     * @return \Illuminate\Database\Eloquent\Collection
     */
    public function newCollection(array $models = [])
    {
        return new CustomCollection($models);
    }
}

一旦你定义了 newCollection 方法，任何时候都可以在 Eloquent 返回的模型的 Collection 实例中获取你的自定义集合实例。如果你想要在应用程序的每个模型中使用自定义集合，则应该在所有的模型继承的模型基类中重写 newCollection 方法。

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