How to return an object and not a string with PHP curl request

Question

I am attempting to request data from a url and am having success for most endpoints except for one. Throughout my troubleshooting, I can retrieve the text and display it in the browser, however, when I try to store it as an object, I get nothing. It actually still stores as a string. I would like to iterate through the object so that I can run calculations on the contents.

Is it because the JSON string is malformed? If so, how do I correct? I have tried a variety of solutions with no success.

Important to note that gzip is required, for that reason I have included 'ob_gzhandler'. the contents only echos when I use gzhandler.

THE ECHOS IN THE FUNCTION ARE FOR TROUBLESHOOTING PURPOSES. THEY ILLUSTRATE WHERE STRINGS ARE BEING PRODUCED AND NOT OBJECTS.

function CallAPI_oanda_v20($instruments)
{
    $curl = curl_init();
    $url = 'https://api-fxtrade.oanda.com/v3/instruments/'.$instruments.'/positionBook';
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
    curl_setopt($ch, CURLOPT_HTTPGET,TRUE);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
          'Content-Type: application/json',
          'Authorization: <USE MY API KEY>')); 
    $response = curl_exec($ch);
    echo gettype($response); //returns "string"
    $json = json_decode($response, true);
    echo gettype($json); //returns "NULL"
    curl_close($ch);
    return $json;
}


$call = CallAPI_oanda_v20("GBP_USD");

ob_start('ob_gzhandler');
//$output = ob_get_contents();
echo $call->positionBook; //returns an error:Trying to get property 'positionBook' of non-object
echo gettype($output); //THIS WILL RETURN "string".

$jsonIterator = new RecursiveIteratorIterator(
    new RecursiveArrayIterator(json_decode($output, TRUE)),
    RecursiveIteratorIterator::SELF_FIRST);

foreach ($jsonIterator as $key => $val) {
    if(is_array($val)) {
        echo "$key:\n";
    } else {
        echo "$key => $val\n";
    }
}

In order to troubleshoot that the call is correct, I echo the contents by graying out the following line:

curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);

Here is the json string that prints:

{"positionBook":{"instrument":"GBP_USD","time":"2019-09-02T00:00:00Z","unixTime":"1567382400","price":"1.21584","bucketWidth":"0.00050","buckets":[{"price":"1.19950","longCountPercent":"0.0189","shortCountPercent":"0.0189"},{"price":"1.20000","longCountPercent":"0.0000","shortCountPercent":"0.0189"},{"price":"1.20100","longCountPercent":"0.0000","shortCountPercent":"0.0189"},{"price":"1.20150","longCountPercent":"0.0000","shortCountPercent":"0.0757"}]}}

Not really sure what your question actually is. What issue are you actually facing? The JSON appears to be valid, $call should in theory be an object. — Jonnix
– Jonnix, Commented Sep 2, 2019 at 0:18
The JSON is valid. Have you tried echo $call->positionBook;? If that doesn't work, what about just echo $call;? — Nick
– Nick, Commented Sep 2, 2019 at 0:18
ob_get_contents returns a string, instead just use $call, which has your object — Lawrence Cherone
– Lawrence Cherone, Commented Sep 2, 2019 at 0:19
Your function returns a value; it doesn’t print anything for ob_start to capture — Tim Morton
– Tim Morton, Commented Sep 2, 2019 at 0:21
What Tim said, and once you're using $call (as per Lawrence' comment), don't decode it a second time. — Jonnix
– Jonnix, Commented Sep 2, 2019 at 0:22

Mark R · Accepted Answer · 2019-09-02 00:52:07Z

1

ob_start('ob_gzhandler');
$output = ob_get_contents();
echo gettype($output); //THIS WILL RETURN "string".

This is exactly what you expect. The output buffer is just a big string that is appended to whenever you write to it. When you gettype($output) you're just getting the output of that buffer, which is nothing to do with any of your other code.

As you're not actually writing anything to said buffer, it will be an empty string.

You're not actually using the result of your function ($call) anywhere. You should be passing it to your recursive array iterator. In your top function you probably want to add TRUE as the second argument to json_decode so it's fully array based.

answered Sep 2, 2019 at 0:52

Mark R

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Comments

user1636985 · Accepted Answer · 2019-09-02 04:12:49Z

SOLVED. I was improperly decoding the gzip string.

$response = gzdecode($response);

This was the key, along with removing:

ob_start('ob_gzhandler');
$output = ob_get_contents();

Here is the solved piece of code:

{
    $curl = curl_init();
    $url = 'https://api-fxtrade.oanda.com/v3/instruments/'.$instruments.'/positionBook';
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
    curl_setopt($ch, CURLOPT_HTTPGET,TRUE);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
          'Content-Type: application/json',
          'Authorization: <USE MY API KEY>')); 
    $response = curl_exec($ch);
    $response = gzdecode($response);
    $json = json_decode($response, true);
    curl_close($ch);
    return $json;
}


$call = CallAPI_oanda_v20("GBP_USD");
echo '<pre>';
print_r($call);
echo '<pre>';```

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