我知道在使用查询生成器时,可以使用
按多列排序...orderBy('column1')->orderBy('column2')
,但现在我正在处理一个集合对象。集合有sortBy
方法,但我还不能弄清楚如何使它为多列工作。直觉上,我最初尝试使用与orderBy
相同的语法。
sortBy('column1')->sortBy('column2)
,但这显然只是按顺序应用排序,最终按column2排序,忽略了column1。我试着
sortBy('column1', 'column2')
,但会抛出错误"asort()期望参数2是长,字符串给定"。使用
sortBy('column1, column2')
不会抛出错误,但排序似乎是相当随机的,所以我真的不知道它实际上是做什么的。我查看了sortBy方法的代码,但不幸的是,我很难理解它是如何工作的。
sortBy()
采用闭包,允许您提供用于排序比较的单个值,但您可以通过将多个属性连接在一起使其成为组合
$posts = $posts->sortBy(function($post) {
return sprintf('%-12s%s', $post->column1, $post->column2);
});
如果您需要对多个列进行排序,您可能需要对它们进行空格填充,以确保"ABC"answers"DEF"出现在"AB"answers"DEF"之后,因此每个列的sprint右填充直到列的长度(至少对最后一列除外)
请注意,如果您可以在查询中使用orderBy,那么从数据库中检索集合时,集合已经就绪排序,通常会更有效率
我在雄辩的集合上使用sort()
找到了一种不同的方法。它可能比填充字段工作得更好,或者至少更容易理解。这个有更多的比较,但我没有为每个项目做sprintf()
。
$items = $items->sort(
function ($a, $b) {
// sort by column1 first, then 2, and so on
return strcmp($a->column1, $b->column1)
?: strcmp($a->column2, $b->column2)
?: strcmp($a->column3, $b->column3);
}
);
正如@derekaug所提到的,sort
方法允许我们输入一个自定义闭包来对集合进行排序。但我认为他的解决方案是有点麻烦,写起来很麻烦,如果有这样的东西就好了:
$collection = collect([/* items */])
$sort = ["column1" => "asc", "column2" => "desc"];
$comparer = $makeComparer($sort);
$collection->sort($comparer);
实际上,这可以通过以下$makeComparer
包装器轻松归档,以生成compare闭包:
$makeComparer = function($criteria) {
$comparer = function ($first, $second) use ($criteria) {
foreach ($criteria as $key => $orderType) {
// normalize sort direction
$orderType = strtolower($orderType);
if ($first[$key] < $second[$key]) {
return $orderType === "asc" ? -1 : 1;
} else if ($first[$key] > $second[$key]) {
return $orderType === "asc" ? 1 : -1;
}
}
// all elements were equal
return 0;
};
return $comparer;
};
$collection = collect([
["id" => 1, "name" => "Pascal", "age" => "15"],
["id" => 5, "name" => "Mark", "age" => "25"],
["id" => 3, "name" => "Hugo", "age" => "55"],
["id" => 2, "name" => "Angus", "age" => "25"]
]);
$criteria = ["age" => "desc", "id" => "desc"];
$comparer = $makeComparer($criteria);
$sorted = $collection->sort($comparer);
$actual = $sorted->values()->toArray();
/**
* [
* ["id" => 5, "name" => "Hugo", "age" => "55"],
* ["id" => 3, "name" => "Mark", "age" => "25"],
* ["id" => 2, "name" => "Angus", "age" => "25"],
* ["id" => 1, "name" => "Pascal", "age" => "15"],
* ];
*/
$criteria = ["age" => "desc", "id" => "asc"];
$comparer = $makeComparer($criteria);
$sorted = $collection->sort($comparer);
$actual = $sorted->values()->toArray();
/**
* [
* ["id" => 5, "name" => "Hugo", "age" => "55"],
* ["id" => 2, "name" => "Angus", "age" => "25"],
* ["id" => 3, "name" => "Mark", "age" => "25"],
* ["id" => 1, "name" => "Pascal", "age" => "15"],
* ];
*/
$criteria = ["id" => "asc"];
$comparer = $makeComparer($criteria);
$sorted = $collection->sort($comparer);
$actual = $sorted->values()->toArray();
/**
* [
* ["id" => 1, "name" => "Pascal", "age" => "15"],
* ["id" => 2, "name" => "Angus", "age" => "25"],
* ["id" => 3, "name" => "Mark", "age" => "25"],
* ["id" => 5, "name" => "Hugo", "age" => "55"],
* ];
*/
现在,既然我们在这里谈论的是Eloquent,那么你很有可能也在使用Laravel。因此,我们甚至可以将$makeComparer()
闭包绑定到IOC并从那里解析它:
// app/Providers/AppServiceProvider.php
// in Laravel 5.1
class AppServiceProvider extends ServiceProvider
{
/**
* ...
*/
/**
* Register any application services.
*
* @return void
*/
public function register()
{
$this->app->bind("collection.multiSort", function ($app, $criteria){
return function ($first, $second) use ($criteria) {
foreach ($criteria as $key => $orderType) {
// normalize sort direction
$orderType = strtolower($orderType);
if ($first[$key] < $second[$key]) {
return $orderType === "asc" ? -1 : 1;
} else if ($first[$key] > $second[$key]) {
return $orderType === "asc" ? 1 : -1;
}
}
// all elements were equal
return 0;
};
});
}
}
现在你可以在任何你需要的地方使用它:
$criteria = ["id" => "asc"];
$comparer = $this->app->make("collection.multiSort",$criteria);
$sorted = $collection->sort($comparer);
$actual = $sorted->values()->toArray();
一个简单的解决方案是将sortBy()按与排序顺序相反的顺序链接多次。缺点是这可能比在同一个回调中一次排序要慢,所以在大型集合中使用该方法风险自负。
$collection->sortBy('column3')->sortBy('column2')->sortBy('column1');