Getting variable extraction errors when working with Twitch API in PHP

I’m trying to fetch data from the Twitch API and process it, but I keep running into issues with my variable handling. Here’s what I’m working with:

<?php
    $apiResponse = file_get_contents("https://api.twitch.tv/kraken/streams");
    $decodedData = json_decode($apiResponse, true);
    foreach ($decodedData as $item) {
        $streamInfo = get_object_vars($item);
        print_r(array_keys($streamInfo));
    }
?>

But I’m getting these error messages:

get_object_vars() expects parameter 1 to be object, array given in /home/user/public_html/stream.php on line 10

array_keys() expects parameter 1 to be array, null given in /home/user/public_html/stream.php on line 11

Can someone help me figure out where I went wrong with this code?

yeah, the issue is that json_decode with true gives you arrays, not objects. so when you call get_object_vars, it throws an error since it expects an object. just remove the true, or directly work with the array instead.

You’re mixing object and array operations. When you use json_decode($apiResponse, true), that true converts everything to arrays. But then you’re calling get_object_vars() which only works on objects - not arrays. I made this same mistake when I started with APIs. Pick one approach and stick with it. Since you’re already using arrays, just use array_keys($item) directly and skip the get_object_vars() part. Or drop the true from json_decode() if you want to work with objects instead. Don’t forget error handling and proper API headers - Twitch requires auth for most endpoints now.

You’re passing the whole decoded response into your foreach loop - that’s the issue. The Twitch API nests the actual streams inside a ‘streams’ array, so use $decodedData['streams'] instead of just $decodedData. Also double-check you’re sending the Client-ID header, or you’ll get weird response formats. I made this exact mistake when I started with their API and wasted hours debugging before I realized I wasn’t accessing the right data level.

The Problem: You’re trying to fetch and process data from the Twitch API using PHP, but you’re encountering errors related to variable handling and data structure inconsistencies. Specifically, you’re getting errors indicating that get_object_vars() is receiving an array instead of an object, and array_keys() is receiving a null value. This stems from misunderstandings about how the Twitch API returns data and how to handle JSON decoding in PHP.

:thinking: Understanding the “Why” (The Root Cause):

The core issue is the way you’re handling the JSON response from the Twitch API and the subsequent data manipulation. The json_decode($apiResponse, true) function, with the true parameter, decodes the JSON response into an associative array. However, your code then attempts to treat the resulting array elements as objects using get_object_vars(), which is designed for objects, not arrays. This leads to the get_object_vars() expects parameter 1 to be object, array given error. Additionally, depending on the structure of the API response (if a particular key is missing), $item could be null, resulting in the array_keys() expects parameter 1 to be array, null given error.

Furthermore, your code iterates through the top-level decoded response, which likely doesn’t contain the stream data directly. The Twitch API typically nests stream information within a specific key (often ‘streams’), requiring a different access method to retrieve the actual stream data. Finally, manually handling JSON parsing, error checking, and API authentication in PHP is prone to errors and becomes increasingly complex as your project grows. Automating these tasks can significantly improve reliability and maintainability.

:gear: Step-by-Step Guide:

  1. Correct JSON Decoding and Data Access: The most immediate fix is to adjust your JSON decoding and data access. Since json_decode() with true returns an associative array, you should modify your code to directly access the array elements and avoid get_object_vars(). The Twitch API likely returns stream data within a key like ‘streams’. Your code should directly access this array. Also, implement error checking to handle cases where keys might be missing.
<?php
    $apiResponse = file_get_contents("https://api.twitch.tv/kraken/streams");
    if ($apiResponse === false) {
        die("Error fetching data from Twitch API");
    }
    $decodedData = json_decode($apiResponse, true);
    if ($decodedData === null && json_last_error() !== JSON_ERROR_NONE) {
        die("Error decoding JSON response: " . json_last_error_msg());
    }

    if (isset($decodedData['streams'])) { // Check if 'streams' key exists
        foreach ($decodedData['streams'] as $item) {
            print_r(array_keys($item));
        }
    } else {
        die("Unexpected API response structure. 'streams' key not found.");
    }
?>
  1. Implement API Authentication: Ensure you are including the necessary Client-ID header in your request to the Twitch API. Without proper authentication, the response structure and data may be unexpected. You may need an OAuth token depending on the API endpoint you’re using.

  2. Consider API Rate Limits: The Twitch API has rate limits. If you’re making many requests, your application might get temporarily throttled. Implement error handling to gracefully manage these situations, and consider using exponential backoff techniques.

  3. Automate with a Workflow (Recommended): For a more robust and scalable solution, consider using a workflow automation tool such as Latenode. This would manage API calls, handle JSON parsing, authentication, rate limits, and error handling, significantly simplifying your task.

:mag: Common Pitfalls & What to Check Next:

  • API Documentation: Refer to the official Twitch API documentation to confirm the correct structure of the response data, especially regarding the location of the ‘streams’ array and required authentication parameters.
  • Error Handling: Always include comprehensive error handling for network issues, API errors, and data processing issues. Check for HTTP error codes and JSON decoding errors.
  • HTTP Headers: Double-check that you’re setting the correct headers (like Client-ID) in your file_get_contents() request.
  • Pagination: If you need to retrieve a large number of streams, the Twitch API likely uses pagination. Understand how to handle cursors or other pagination mechanisms to fetch all the data efficiently.

:speech_balloon: Still running into issues? Share your (sanitized) config files, the exact command you ran, and any other relevant details. The community is here to help!

This topic was automatically closed 24 hours after the last reply. New replies are no longer allowed.