无法在 PHP 中修改 JSON 文件

Question

This is my json.json file content

{
    "Title": "Hello World",
    "Inputs": [
             {
               "Id": "1",
               "Title": "One"
             },
             {
               "Id": "15",
               "Title": "Fifteen"
             }
          ]
 }

I am trying to modify it as the follows -

$text = file_get_contents("json.json");
$json = json_decode($text,true);

foreach($json["Inputs"] as $input){

    if($input["Id"]== "15"){
        $input["Title"] = "This is from me.";
    }       
}

$new = json_encode($json);
file_put_contents('json.json', $new);

But the file is not being updated.

Any idea?

Answer 1

Your JSON in the example is improperly formatted, but the issue you are having is that you do not set the title in the original array. You change the copy that is passed to the foreach loop.

Change your foreach loop to this and your changes should be shown:

foreach($json["Inputs"] as $key => $input){
    if($input["Id"]== "15"){
        $json["Inputs"][$key]["Title"] = "This is from me.";
    }
}

The foreach loop takes the value by reference, so changing the $json['Inputs'] will change the original value, whereas changing $input modifies the copy that is passed to the loop, and does not change the original json data. There are ways to pass by reference to the foreach loop, but this seems like a simpler solution.