相同的json数组删除过程针对不同的值位置产生不同的结果数组 [英] Same json array delete process produces different result array for different position of value

问题描述

我有一个json数组.其中我有3个值.当我删除第一个或第二个值时，删除后的结果数组是一种格式.但是，当我删除最后一个值时，结果数组总是会变化.我通过将其转换回字符串来回显该数组.

I have a json array. in which i have 3 values. when i delete first or second value the resultant array after deletion is one format. But when i delete the last value always the resultant array changes. i am echoing the array by converting it back to string.

当我删除除最后一个值以外的任何值时，例如第一个或第二个值或任何其他值

When i delete any value except the last one, that is like 1st or 2nd or any other value

result = {"1":{"name":"cat"}，"2":{"name":"elephant"}}

result = {"1":{"name":"cat"},"2":{"name":"elephant"}}

我在这里删除了第一个值-狗

Here i deleted first value - dog

$animals = '{
 "0":{"name":"dog"},
 "1":{"name":"cat"},
 "2":{"name":"elephant"}
 }';
$animals = json_decode($animals, true);
$del_value = "elephant";
$loginArray = array('name' => $del_value);
if (in_array($loginArray, $animals)) {
    foreach ($animals as $key => $value) {
        if (in_array($del_value, $value)) {
            unset($animals[$key]);
        }
    }
}
$animals_string = json_encode($animals);
echo $animals_string;

但是当我删除最后一个值时，它将创建不同的格式

but When i delete the last value it creates different format

result = [{{name:" dog}，{" name:" cat}]

result = [{"name":"dog"},{"name":"cat"}]

在这里我删除了最后一个值-大象

Here i deleted last value - elephant

$animals = '{
 "0":{"name":"dog"},
 "1":{"name":"cat"},
 "2":{"name":"elephant"}
 }';
$animals = json_decode($animals, true);
$del_value = "elephant";
$loginArray = array('name' => $del_value);
if (in_array($loginArray, $animals)) {
    foreach ($animals as $key => $value) {
        if (in_array($del_value, $value)) {
            unset($animals[$key]);
        }
    }
}
$animals_string = json_encode($animals);
echo $animals_string;

推荐答案

此行为是预期的.

PHP支持2种类型的数组:

PHP supports 2 type of array:

1. 关联性:其中索引可以是字符串或非顺序整数
2. 数字索引:其中索引是从0开始的连续整数

但是JSON仅支持第二种类型的数组，因此，当您将关联数组转换为JSON时，您会得到一个对象.

However JSON only supports the 2nd type of array, therefore when you convert an associative array to JSON you get an object instead.

示例:

print_r(json_encode([ 1,2,3,4 ])); //Prints [1,2,3,4]
print_r(json_encode([ 0=> 1, 1=>2, 2=>3, 3=>4 ])); //also prints [1,2,3,4]
print_r(json_encode([ "a" => 1, "b" => 2 ])); //Prints {"a":1,"b":2}
print_r(json_encode([ 1 => "a" , 2 => "b" ])); //Prints {"1":"a","2":"b"}

通过删除原始键将PHP数组(任何类型)强制为JSON数组:

Force PHP array (of any type) to JSON array by dropping original keys:

$animals_string = json_encode(array_values($animals)); //Will always have form : [{"name": "X" },{"name":"Y"}]

将PHP数组(任何类型)强制为JSON对象:

Force PHP array (of any type) to JSON object:

$animals_string = json_encode((object)$animals); //Will always have form : {"i1":{"name":"X"},"i2":{"name":"Y"}}

在您的特定情况下的问题是，您的JSON对象被转换为一个PHP数字索引数组，该数组在被编码回它时将成为一个JSON数组:

The problem in your particular case is that your JSON object gets translated into a PHP numerically indexed array which when encoded back it becomes a JSON array:

$animals = '{
   "0":{"name":"dog"},
   "1":{"name":"cat"},
   "2":{"name":"elephant"}
 }';
$animals = json_decode($animals, true);

echo json_encode($animals); 

回声

[{"name":"dog"}，{"name":"cat"}，{"name":"elephant"}]

[{"name":"dog"},{"name":"cat"},{"name":"elephant"}]

如果删除除最后一个索引以外的一个索引，则将使PHP数组具有关联性，该关联将转换为JSON对象.

If you remove one of the indexes other than the last then this makes the PHP array associative which gets translated to a JSON object.

这就是PHP的工作方式:如果您想要不同的输出，则需要对其进行明确说明，如下所示:

This is is how PHP works if you want a different output you need to be explicit about it like below:

$animals = '{
 "0":{"name":"dog"},
 "1":{"name":"cat"},
 "2":{"name":"elephant"}
 }';
$animals = json_decode($animals, true);
$del_value = "elephant";
$loginArray = array('name' => $del_value);
if (in_array($loginArray, $animals)) {
    foreach ($animals as $key => $value) {
        if (in_array($del_value, $value)) {
            unset($animals[$key]);
        }
    }
}
$animals_string = json_encode((object)$animals);
echo $animals_string;  //Always the same format

我希望这会有所帮助.

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