Eloquent 集合 · Laravel 5.4 完全开发手册

* * * * * [TOC] ## 简介默认情况下 Eloquent 返回的都是一个 `Illuminate\Database\Eloquent\Collection` 对象的实例，包含通过 `get` 方法或是访问一个关联来获取到的结果。Eloquent 集合对象继承了 Laravel [集合基类](https://laravel-china.org/docs/laravel/5.4/collections)，因此它自然也继承了许多可用于与 Eloquent 模型交互的方法。当然，所有集合都可以作为迭代器，来让你像遍历一个 PHP 数组一样来遍历一个集合： ~~~ $users = App\User::where('active', 1)->get(); foreach ($users as $user) { echo $user->name; } ~~~ 然而，集合比数组更强大的地方是其使用了各种 map / reduce 的直观操作。例如，我们移除所有未激活的用户模型和收集其余各个用户的名字： ~~~ $users = App\User::where('active', 1)->get(); $names = $users->reject(function ($user) { return $user->active === false; }) ->map(function ($user) { return $user->name; }); ~~~ > {note} 大部分的 Eloquent 集合会返回新的「Eloquent 集合」实例，但是 `pluck`, `keys`, `zip`, `collapse`, `flatten` 和 `flip` 方法会返回 [基础集合](https://laravel-china.org/docs/laravel/5.4/collections) 实例。 > > 相应的，如果一个 `map` 操作返回一个不包含任何 Eloquent 模型的集合，那么它将会自动转换成基础集合。 ## 可用的方法 ### 集合对象所有 Eloquent 集合都继承了基础的 [Laravel 集合](https://laravel-china.org/docs/laravel/5.4/collections) 对象。因此，他们也继承了所有集合类提供的强大的方法： [all](https://laravel-china.org/docs/laravel/5.4/collections#method-all) [avg](https://laravel-china.org/docs/laravel/5.4/collections#method-avg) [chunk](https://laravel-china.org/docs/laravel/5.4/collections#method-chunk) [collapse](https://laravel-china.org/docs/laravel/5.4/collections#method-collapse) [combine](https://laravel-china.org/docs/laravel/5.4/collections#method-combine) [contains](https://laravel-china.org/docs/laravel/5.4/collections#method-contains) [count](https://laravel-china.org/docs/laravel/5.4/collections#method-count) [diff](https://laravel-china.org/docs/laravel/5.4/collections#method-diff) [diffKeys](https://laravel-china.org/docs/laravel/5.4/collections#method-diffkeys) [each](https://laravel-china.org/docs/laravel/5.4/collections#method-each) [every](https://laravel-china.org/docs/laravel/5.4/collections#method-every) [except](https://laravel-china.org/docs/laravel/5.4/collections#method-except) [filter](https://laravel-china.org/docs/laravel/5.4/collections#method-filter) [first](https://laravel-china.org/docs/laravel/5.4/collections#method-first) [flatMap](https://laravel-china.org/docs/laravel/5.4/collections#method-flatmap) [flatten](https://laravel-china.org/docs/laravel/5.4/collections#method-flatten) [flip](https://laravel-china.org/docs/laravel/5.4/collections#method-flip) [forget](https://laravel-china.org/docs/laravel/5.4/collections#method-forget) [forPage](https://laravel-china.org/docs/laravel/5.4/collections#method-forpage) [get](https://laravel-china.org/docs/laravel/5.4/collections#method-get) [groupBy](https://laravel-china.org/docs/laravel/5.4/collections#method-groupby) [has](https://laravel-china.org/docs/laravel/5.4/collections#method-has) [implode](https://laravel-china.org/docs/laravel/5.4/collections#method-implode) [intersect](https://laravel-china.org/docs/laravel/5.4/collections#method-intersect) [isEmpty](https://laravel-china.org/docs/laravel/5.4/collections#method-isempty) [keyBy](https://laravel-china.org/docs/laravel/5.4/collections#method-keyby) [keys](https://laravel-china.org/docs/laravel/5.4/collections#method-keys) [last](https://laravel-china.org/docs/laravel/5.4/collections#method-last) [map](https://laravel-china.org/docs/laravel/5.4/collections#method-map) [max](https://laravel-china.org/docs/laravel/5.4/collections#method-max) [merge](https://laravel-china.org/docs/laravel/5.4/collections#method-merge) [min](https://laravel-china.org/docs/laravel/5.4/collections#method-min) [only](https://laravel-china.org/docs/laravel/5.4/collections#method-only) [pluck](https://laravel-china.org/docs/laravel/5.4/collections#method-pluck) [pop](https://laravel-china.org/docs/laravel/5.4/collections#method-pop) [prepend](https://laravel-china.org/docs/laravel/5.4/collections#method-prepend) [pull](https://laravel-china.org/docs/laravel/5.4/collections#method-pull) [push](https://laravel-china.org/docs/laravel/5.4/collections#method-push) [put](https://laravel-china.org/docs/laravel/5.4/collections#method-put) [random](https://laravel-china.org/docs/laravel/5.4/collections#method-random) [reduce](https://laravel-china.org/docs/laravel/5.4/collections#method-reduce) [reject](https://laravel-china.org/docs/laravel/5.4/collections#method-reject) [reverse](https://laravel-china.org/docs/laravel/5.4/collections#method-reverse) [search](https://laravel-china.org/docs/laravel/5.4/collections#method-search) [shift](https://laravel-china.org/docs/laravel/5.4/collections#method-shift) [shuffle](https://laravel-china.org/docs/laravel/5.4/collections#method-shuffle) [slice](https://laravel-china.org/docs/laravel/5.4/collections#method-slice) [sort](https://laravel-china.org/docs/laravel/5.4/collections#method-sort) [sortBy](https://laravel-china.org/docs/laravel/5.4/collections#method-sortby) [sortByDesc](https://laravel-china.org/docs/laravel/5.4/collections#method-sortbydesc) [splice](https://laravel-china.org/docs/laravel/5.4/collections#method-splice) [sum](https://laravel-china.org/docs/laravel/5.4/collections#method-sum) [take](https://laravel-china.org/docs/laravel/5.4/collections#method-take) [toArray](https://laravel-china.org/docs/laravel/5.4/collections#method-toarray) [toJson](https://laravel-china.org/docs/laravel/5.4/collections#method-tojson) [transform](https://laravel-china.org/docs/laravel/5.4/collections#method-transform) [union](https://laravel-china.org/docs/laravel/5.4/collections#method-union) [unique](https://laravel-china.org/docs/laravel/5.4/collections#method-unique) [values](https://laravel-china.org/docs/laravel/5.4/collections#method-values) [where](https://laravel-china.org/docs/laravel/5.4/collections#method-where) [whereStrict](https://laravel-china.org/docs/laravel/5.4/collections#method-wherestrict) [whereIn](https://laravel-china.org/docs/laravel/5.4/collections#method-wherein) [whereInLoose](https://laravel-china.org/docs/laravel/5.4/collections#method-whereinloose) [zip](https://laravel-china.org/docs/laravel/5.4/collections#method-zip) ## 自定义集合如果你需要使用一个自定义的 `Collection` 对象到自己的扩充方法上，则可以在模型中重写 `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，则可在任何 Eloquent 返回该模型的 `Collection` 实例时，接收到一个你的自定义集合的实例。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。