PHP - json_decode giving 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 e.g. '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

Ok thanks. Are there any ways to convert it, without having to store it in 2 separate files? — Andy
– Andy, Commented Aug 22, 2017 at 9:03
@RahulMeshram Huh? Passing true to json_decode isn't going to help if the input isn't valid JSON. — Jonnix
– Jonnix, Commented Aug 22, 2017 at 9:08

Jerodev · Accepted Answer · 2017-08-22 09:04:35Z

4

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"}
    ]
}

answered Aug 22, 2017 at 9:04

Jerodev

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5 Comments

Andy Over a year ago

I can reformat the file so it looks like that. However this will inevitably break what I'd had a hard time implementing to populate a select element based on the file contents - details are here stackoverflow.com/questions/45795518/…. So is it possible to populate a select based on the format you've given? I'm trying to think of a solution which will cover both requirements. Thanks.

Jerodev Over a year ago

That is not a very good solution in javascript. You should look at the $.getJSON() function to get the json file at the client side.

Andy Over a year ago

@Jerodev can you confirm that that's how the string should be formatted? Because it's still giving NULL as the output when json_decode()-ing that.

Jerodev Over a year ago

This is most certainly a valid json string. Please update your answer with your new string so we can see what the problem is.

Andy Over a year ago

My fault. When I'd enclosed code and name in quotes I'd put the colon inside the string! It's fixed now. Thanks for your patience/help.

cipher · Accepted Answer · 2017-08-22 09:17:51Z

0

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.

edited Aug 22, 2017 at 9:17

answered Aug 22, 2017 at 9:14

cipher

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2 Comments

Andy Over a year ago

Thanks. I'm more than happy to reformat the file as per Jerodev's suggestion. This problem has originated from advice I was given in stackoverflow.com/questions/45795518/… from someone who had a 9k reputation, and their solution seemed to work for that particular problem. I'm going to reformat my file and look into $.getJSON() as suggested by @Jerodev.

cipher Over a year ago

Cool. Good choice!

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