当我尝试解码来自youtube api的响应时，json_decode返回null

Question

So I try to create a oauth connection with youtube api but I have a problem with decoding the response. My problem is here:

public function getCallbackUrl($code)
{

    // Grab the returned code and extract the access token.
    $this->params = [
        'code'          => $code,
        'client_id'     => '#####',
        'client_secret' => '####',
        'redirect_uri'  => '######',
        'grant_type'    => 'authorization_code'
    ];

    // Get access token
    $command = 'curl --data "' . http_build_query($this->params) . '" https://accounts.google.com/o/oauth2/token';
    exec($command, $resultToken);
    $resultToken = json_decode($resultToken[0]);

After I make the exec $resultToken returns like this:

array(5) { [0]=> string(1) "{" [1]=> string(93) " "access_token" : "###########"," [2]=> string(26) " "token_type" : "Bearer"," [3]=> string(21) " "expires_in" : 3599" [4]=> string(1) "}" }

But when I try to json_decode to obtain an array: $resultToken = json_decode($resultToken[0]); I get a result NULL Can anyone explain to me why please? Any help is welcomed, thank you for your time!

var_dump($resultToken[0]) = NULL;

Answer 1

You are trying to decode a value which is not valid JSON. Verify whether your API request is returning the correct response. From the documentation:

NULL is returned if the json cannot be decoded or if the encoded data is deeper than the recursion limit.

On a side note, you are using a system call to invoke cURL. Consider using the native PHP cURL extension or a proper library.