Making cURL return in the format of json

Question

I'm currently trying to use a cURL method to POST data to an external server and need it to return data in json formatted code, right now the only format it returns in is xml... but I can't use that data to continue on.

Below is what I've got so far.

$ch = curl_init();
    curl_setopt( $ch, CURLOPT_URL, $flickr_upload ); 
    curl_setopt( $ch, CURLOPT_POST, true );
    curl_setopt( $ch, CURLOPT_POSTFIELDS, $parameters_string );
    $result = curl_exec( $ch ); 
curl_close( $ch );

I've heard / read some stuff about needing to add an HTTPHEADER option, which I have tried doing in the following manner:

curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/json'));

But when I tried this I just got an error from the external site that I'm POST-ing to.

Below is my entire function...

public function uploadPhotos( $photo, $title = null, $tags = null ) {

    // Function specific variables
    $flickr_upload          = $this->flickr_upload_call;
    $access_token               = "my_access_token";
    $access_token_secret        = "my_access_token_secret";

    // Authorization method
    $url  = "format=" . $this->format;
    $url .= "&nojsoncallback=1";
    $url .= "&oauth_consumer_key=" . $this->flickr_key;
    $url .= "&oauth_nonce=" . $this->nonce;
    $url .= "&oauth_signature_method=" . $this->sig_method;
    $url .= "&oauth_timestamp=" . $this->timestamp;
    $url .= "&oauth_token=" . $access_token;
    $url .= "&oauth_version=1.0";

    $baseurl            = "POST&" . urlencode( $flickr_upload ) . "&" . urlencode( $url );
    $hashkey            = $this->flickr_secret . "&" . $access_token_secret;
    $oauth_signature    = base64_encode( hash_hmac( 'sha1', $baseurl, $hashkey, true ));

    $url_parameters = array(
        'format'                =>$this->format,
        'nojsoncallback'        =>'1',
        'oauth_consumer_key'    =>$this->flickr_key,
        'oauth_nonce'           =>$this->nonce,
        'oauth_signature_method'=>$this->sig_method,
        'oauth_timestamp'       =>$this->timestamp,
        'oauth_token'           =>$access_token,
        'oauth_version'         =>'1.0',
        'oauth_signature'       =>$oauth_signature
    );

    //* Now that we have encoded the parameters for our ouath_signature
    //* and have reformated them for the url we need to send... we must
    //* re-urlencode them too. 

    $parameters_string = "";
    foreach ( $url_parameters as $key=>$value )
        $parameters_string .= "$key=" . urlencode( $value ) . "&";

    $parameters_string = rtrim( $parameters_string, '&' );
    $url = $flickr_upload . "&" . $parameters_string;

    $ch = curl_init();
        curl_setopt( $ch, CURLOPT_URL, $flickr_upload ); 
        curl_setopt( $ch, CURLOPT_POST, true );
        curl_setopt( $ch, CURLOPT_POSTFIELDS, $parameters_string );
        $result = curl_exec( $ch ); 
    curl_close( $ch );

    var_dump( json_decode( $result, true ));

    if (!curl_exec( $ch )) {
        // if curl_exec() returned false and thus failed
        echo 'An error has occurred.';
    }

} // end Upload images

I have seen some people json_encodeing the variable that they use for the POSTFIELDS option and I'm wondering if that is why it's not working correctly?

Do you have control over what the external server returns (I.e. is it your server?). If it is returning xml then it is set to return xml. — superphonic, Dec 17 '13 at 15:02
You either need the server to return json, or you need to convert the xml to json. See this http://stackoverflow.com/questions/8830599/php-convert-xml-to-json — Mattt, Dec 17 '13 at 15:03
You will need to parse the xml into a desired array and then json_encode it. If the response is out of your hands or from another company. Maybe ask the people you are sending the request to if there is a parameter to pass to make it a json response — Ryan, Dec 17 '13 at 15:04
@superphonic: No, I do not have control of the external server. It is flickr. — Designer 17, Dec 17 '13 at 16:04
In which case the documentation is your friend. See @Andrew answer below. — superphonic, Dec 17 '13 at 16:05

score 3 · Accepted Answer · edited May 23 '17 at 12:30

You cannot change the return format of a flickr upload request... it always returns xml.

You can, however, quite easily convert this xml snippet to json using the following method:

$xml_snippet = simplexml_load_string( $result );
$json_convert = json_encode( $xml_snippet );
$json = json_decode( $json_convert );

Now any calls that need to use the cURL's returned data just use the $json variable.

Special thanks to @AntonioMax over at: PHP convert XML to JSON

score 2 · Answer 2 · answered Dec 17 '13 at 15:04

2

I assume you use flickr API. Use format=json parameter as stated in official docs at http://www.flickr.com/services/api/response.json.html

answered Dec 17 '13 at 15:04

Andrew

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Yes, I am using flickr's api. Also I am using their format parameter already... that's why I'm so confused. `format = $this->format` is equal to `json`. Not sure why it's returning xml when that param. is set! – Designer 17 Dec 17 '13 at 16:09
Once I add `HTTPHEADER array()` to the cURL method I receive (in xml) `error code: 100 msg="Invalid API Key (Key has invalid format)"` ??? – Designer 17 Dec 17 '13 at 16:49

Making cURL return in the format of json

2 Answers2