Getting file upload size in WordPress with check_upload_size

The check_upload_size function in WordPress is a mechanism that checks the size of an uploaded file. It is used in the context of file upload operations in WordPress. The primary task of this function is to compare the size of the uploaded file against the maximum upload size limit set in the WordPress configuration.

When an upload operation is performed, the check_upload_size function is invoked to ensure that the file being uploaded does not exceed the specified maximum size limit. If the uploaded file size is larger than the maximum allowed size, the function will return an error. This helps in maintaining the storage efficiency and ensures that the website does not get overloaded with large files.

This function is a part of WordPress’s file handling API and is typically used in the file upload process, which involves uploading media files, themes, plugins, or other types of files to the WordPress site. The function plays a crucial role in managing the file upload process and maintaining the overall performance and efficiency of the WordPress site.

Parameters Accepted by the check_upload_size Function

The check_upload_size function in WordPress accepts one required parameter. The parameter is as follows:

  • $file (array): This is a compulsory parameter which represents a specific file from the $_FILES array.

Return Value of the check_upload_size Function

The check_upload_size function returns an array. This array is essentially the $_FILES array element. If the file size is beyond the allowed quota, the ‘error’ key within the array is set. In case the file size is within the permissible limit, the ‘error’ key remains empty.

Examples

How to Check if Uploaded File Size Exceeds Quota

 $file = $_FILES['upload_file']; // get the uploaded file
 $checked_file = check_upload_size($file); // check the file size

 if (!empty($checked_file['error'])) { // if there is an error
 echo '<p>File size exceeds quota.</p>';
 } else {
 echo '<p>File size is within quota.</p>';
 }

In this example, we first get the uploaded file from the $_FILES array. We then pass this file to the check_upload_size function. If the function returns an array with a non-empty ‘error’ key, it means the file size exceeds the quota. Otherwise, the file size is within the quota.

How to Handle File Size Exceeding Quota Error

 $file = $_FILES['upload_file']; // get the uploaded file
 $checked_file = check_upload_size($file); // check the file size

 if (!empty($checked_file['error'])) { // if there is an error
 die('<p>File size exceeds quota. Please upload a smaller file.</p>');
 }

 // continue with file processing

In this example, we halt the script execution if the uploaded file size exceeds the quota. We use the die function to display an error message and stop the script.

How to Return File Size Error as JSON

 $file = $_FILES['upload_file']; // get the uploaded file
 $checked_file = check_upload_size($file); // check the file size

 if (!empty($checked_file['error'])) { // if there is an error
 echo json_encode(['error' => 'File size exceeds quota.']);
 } else {
 echo json_encode(['success' => 'File size is within quota.']);
 }

In this example, we return the result of the file size check as a JSON response. We use the json_encode function to convert an array to a JSON string. If the file size exceeds the quota, we return an error message. Otherwise, we return a success message.

Conclusion

The check_upload_size function in WordPress is a built-in mechanism designed to validate the size of an uploaded file against the maximum upload size limit set on the server. This function plays a crucial role in ensuring that the server’s resources are not overwhelmed by excessively large file uploads. It is commonly used in scenarios where file uploads are involved, such as media uploads, theme installations, and plugin installations, to name a few. By utilizing the check_upload_size function, developers can provide a more controlled and stable environment for file uploads in their WordPress projects.

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