PHP - json_decode 给出 NULL

Question

I'm trying to use the advice given in How to search through a JSON Array in PHP to lookup country names based on a country code in a .json file.

I have a file, countrycodes.js which is formatted like this:

countries = [
    {code: "GB", name: "United Kingdom"},
    {code: "AF", name: "Afghanistan"},
    // ...
    {code: "ZM", name: "Zambia"},
    {code: "ZW", name: "Zimbabwe"}
];

The variable, countries has to be there because part of the application relies on this.

In PHP I've done the following:

$str = file_get_contents('countrycodes.js');
var_dump($str);

This outputs a string:

string(9642) "countries = [
{code: "GB", name: "United Kingdom"},
{code: "AF", name: "Afghanistan"},
// ...

However, when I try and json_decode it, the following gives NULL :

$str = file_get_contents('countrycodes.js');
$json = json_decode($str);
var_dump($json);

I don't know why this is because json_decode accepts a string, and this is what's given on the link I posted above? I tried removing the JavaScript variable ( countries = ) but this made no difference.

Ultimately what I want to do is be able to give PHP a country code such as 'GB' and get it to return the appropriate name eg 'United Kingdom'. My understanding of this is the json_decode part will need to work before this is possible.

For reference, the reason countries = was being used is for populating a <select> element based on advice given here: Populating select using ajax json array

Answer 1

If you json_decode returns null , this means the input string is not in a valid format. Your file contains a javascript variable and not a JSON string.

This is how the string should probably formatted:

{
    "countries": [
        {"code": "GB", "name": "United Kingdom"},
        {"code": "AF", "name": "Afghanistan"},
        {"code": "ZM", "name": "Zambia"},
        {"code": "ZW", "name": "Zimbabwe"}
    ]
}

Answer 2

Extending on Jerodev's answer, if you cannot will not change the representation, you could do the following.

Modify your file so that you wrap the keys with quotes. Something like,

countries = [
    {"code": "GB", "name": "United Kingdom"},
    {"code": "AF", "name": "Afghanistan"},
    // ...
    {"code": "ZM", "name": "Zambia"},
    {"code": "ZW", "name": "Zimbabwe"}
];

And then just decode the json part.

$str = file_get_contents('countrycodes.js');
$str = substr($str,12, strlen($str)-13); // do not include the semicolon
var_dump(json_decode($str));

However this is not a good approach, so I'd still suggest to look for other ways to populate the data in your element.

Note that 12 is the position where [ starts, if you have made any changes to variable names or spaces, that (and 13 ) needs to change.