Laravel 集合 where 返回的数据格式问题

where以一对指定的「键／数值」筛选集合：

$collection = collect([
    ['product' => 'Desk', 'price' => 200],
    ['product' => 'Chair', 'price' => 100],
    ['product' => 'Bookcase', 'price' => 150],
    ['product' => 'Door', 'price' => 100],
]);

$filtered = $collection->where('price', 100);

$filtered->all();

/*
[
    ['product' => 'Chair', 'price' => 100],
    ['product' => 'Door', 'price' => 100],
]
*/

实际运行结果是：

$collection = collect([
        ['product' => 'Desk', 'price' => 200],
        ['product' => 'Chair', 'price' => 100],
        ['product' => 'Bookcase', 'price' => 150],
        ['product' => 'Door', 'price' => 100],
]);

$filtered = $collection->where('price', 100);
return response()->json($filtered->all());
/*
// json结果里把索引当做了key
{
    "1": {
        "product": "Chair",
        "price": 100
    },
    "3": {
        "product": "Door",
        "price": 100
    }
}

// dd后的结果，key不连续了
array:2 [
  1 => array:2 [
    "product" => "Chair"
    "price" => 100
  ]
  3 => array:2 [
    "product" => "Door"
    "price" => 100
  ]
]
*/

使用array_values后的结果：

$collection = collect([
        ['product' => 'Desk', 'price' => 200],
        ['product' => 'Chair', 'price' => 100],
        ['product' => 'Bookcase', 'price' => 150],
        ['product' => 'Door', 'price' => 100],
]);

$filtered = $collection->where('price', 100);
$filteredAll = array_values($filtered->all());
dd($filteredAll);
return response()->json($filteredAll);

/*
[
    {
        "product": "Chair",
        "price": 100
    },
    {
        "product": "Door",
        "price": 100
    }
]

array:2 [
  0 => array:2 [
    "product" => "Chair"
    "price" => 100
  ]
  1 => array:2 [
    "product" => "Door"
    "price" => 100
  ]
]
*/

应该和json_encode有关，连续索引0、1、2这样的转换后不转换索引为key，不连续的就会把索引转换为key
所以where查找后需要将数组索引重置
这里使用array_values，也可以使用

$filteredAll = array_merge($filtered, []);

或

$filteredAll = $filtered->all();
sort($filteredAll);

查找后得到结果：
jsonencode()只将索引数组（indexed array）转为数组格式，而将关联数组（associative array）转为对象格式
比如，现在有一个索引数组

　　$arr = Array('one', 'two', 'three'); 　　
　　echo json_encode($arr); 　

结果为：

　　["one","two","three"] 　

如果将它改为关联数组：

　　$arr = Array('1'=>'one', '2'=>'two', '3'=>'three'); 　　
　　echo json_encode($arr); 　

结果就变了：

　　{"1":"one","2":"two","3":"three"}

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