php将字符串化对象作为null

Question

I'm trying to pass a some information to a php page with jquery ajax. I really can't understand why the php page keeps echoing back that the strinified JSON i'm sending is null

//php
if ($type == "new" || $type == "update"){
    $new_address = json_decode($_REQUEST['address'], true);
    echo json_encode($new_address); //Null
}

//js
var string_encoded_address = JSON.stringify(address_obj.address);
string_encoded_address = encodeURIComponent(string_encoded_address);
console.log(string_encoded_address);
$.ajax({
    type: "post",
    url: "order_queries_templates/queries/address.php",
    data: "type=new&user_id=" + user_id + "&address=" + string_encoded_address,
    dataType: "json",
    success: function (returnedData) {
        console.log(returnedData);
    }
});

this gives me a string for my data property:

type=new&user_id=8244&address=%7B%22companyName%22%3A%22test%20company%22%2C%22address1%22%3A%222420%20sample%20Road%22%2C%22city%22%3A%22SIOUX%20CITY%22%2C%22state%22%3A%22IA%22%2C%22zip%22%3A%2251106%22%2C%22cityStateZip%22%3A%22SIOUX%20CITY%2C%20IA%2051106%22%7D 

What could be wrong with it? Thanks!

Answer 1

The reason why your code doesn't work is because you have magic_quotes_gpc enabled. It adds escaping to the double quotes, as can be seen using this cli script:

$s = 'address=%7B%22companyName%22%3A%22test%20company%22%7D';
// parse query string into array
parse_str($s, $a);
// print address portion
echo $a['address'], "
";

php -dmagic_quotes_gpc=On test.php

Output:

{\"companyName\":\"test company\"}

The additional escaping breaks json_decode() so it returns null.

Turning magic_quotes_gpc off will fix this particular issue, either by using .htaccess or editing the php.ini.

However, it's far easier to just let jQuery take care of the serialization for you:

$.ajax({
    ...,
    data: {
      type:'new', 
      user_id: user_id, 
      adress: address_obj.address
    },
    ...
});

In this case you won't have to json_decode() on the server anymore, just reference $_POST['address'] directly.