有条件地排序以实现记录的均匀分布答案

【问题标题】：Conditionally sorting for an even distribution of records有条件地排序以实现记录的均匀分布
【发布时间】：2020-11-25 06:10:17
【问题描述】：

假设我在这样的Item 模型中有 10 条 Eloquent 模型记录（为简单起见，表示为 JSON）：

[
  {id: 1, name: 'Item 1', featured: false},
  {id: 2, name: 'Item 2', featured: true},
  {id: 3, name: 'Item 3', featured: false},
  {id: 4, name: 'Item 4', featured: false},
  {id: 5, name: 'Item 5', featured: false},
  {id: 6, name: 'Item 6', featured: false},
  {id: 7, name: 'Item 7', featured: true},
  {id: 8, name: 'Item 8', featured: false},
  {id: 9, name: 'Item 9', featured: false},
  {id: 10, name: 'Item 10', featured: true},
]

我想首先通过id 升序组织此列表，然后分配记录，这样featured = false 的每两条记录后跟featured = true 的一条记录。

结果如下所示：

[
  {id: 1, name: 'Item 1', featured: false},
  {id: 3, name: 'Item 3', featured: false},
  {id: 2, name: 'Item 2', featured: true},
  {id: 4, name: 'Item 4', featured: false},
  {id: 5, name: 'Item 5', featured: false},
  {id: 7, name: 'Item 7', featured: true},
  {id: 6, name: 'Item 6', featured: false},
  {id: 8, name: 'Item 8', featured: false},
  {id: 10, name: 'Item 10', featured: true},
  {id: 9, name: 'Item 9', featured: false},
]

我将如何使用 Eloquent 集合或查询来做到这一点？

【问题讨论】：

标签： laravel sorting eloquent laravel-8

【解决方案1】：

这是一个使用集合的工作解决方案（我相信它可以清理很多）：

$result = collect($items)->sortBy('id')->partition(function ($i) {
  return $i['featured'];
})->pipe(function ($groups) {
   return $groups->last()->chunk(2)->reduce(function ($carry, $item) use ($groups) {
      $item->each(function ($i) use ($carry) {
         $carry->push($i);
      });
      
      if ($groups->first()->isNotEmpty()) {
         $carry->push($groups->first()->shift());
      }

      return $carry;
   }, collect());
});

看到它在行动here。

【讨论】：