How to achieve php json_encode array without conversion

The json_encode function in PHP converts a PHP variable into a JSON format string. The most common is to convert an array in PHP to a JSON formatted string. However, in some cases you may want the json_encode function to not convert the array. In this article, we will explore how to achieve this goal.

First, let’s take a look at how the json_encode function converts arrays by default. Suppose we have the following PHP array:

$array = array(
    "name" => "John",
    "age" => 30,
    "hobbies" => array("reading", "swimming", "traveling")
);

When we pass this array to the json_encode function, the function will return the following JSON formatted string:

{
    "name": "John",
    "age": 30,
    "hobbies": ["reading", "swimming", "traveling"]
}

As you can see, the function has " hobbies" key value is converted from a PHP subarray to a JSON array. This is useful in most cases because it provides us with a way to recursively convert PHP data to JSON format layer by layer.

However, in some cases, we want the json_encode function not to convert the arrays, but to keep them as original PHP arrays. There is a way to achieve this and that is to use special placeholders in the array.

We can replace each subarray in the array with a placeholder, and then use a callback function in the json_encode function to replace these placeholders back to normal subarrays. Here is an example:

$array = array(
    "name" => "John",
    "age" => 30,
    "hobbies" => "[[subarray]]"
);

function replaceSubarrays($data) {
    if(is_array($data)) {
        if(in_array("[[subarray]]", $data)) {
            $data = array_map("replaceSubarrays", $data);
        }
    } elseif ($data == "[[subarray]]") {
        $data = array();
    }
    return $data;
}

$json = json_encode(array_map("replaceSubarrays", $array));

echo $json;

In this example, we replace the value of the "hobbies" key with "[[subarray]]", which is a special placeholder indicating that the value is a subarray . We also define a callback function replaceSubarrays to handle this placeholder. It iterates through all array elements recursively, finds all subarrays containing placeholders, and replaces them with empty arrays. We then use the json_encode function and the array_map function to pass the entire array to the callback function and replace the subarray.

When we run this example, we will get the following string in JSON format:

{
    "name": "John",
    "age": 30,
    "hobbies": "[[subarray]]"
}

As we expected, the value of the "hobbies" key is not converted to a JSON array, but Is reserved as "[[subarray]]" string.

This approach using placeholders does require some extra work, but it allows the json_encode function to retain the original PHP array, allowing us to process the data in a higher level way.

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