Using wp_send_json_error to send JSON error response in WordPress

The wp_send_json_error function is a part of the WordPress core. It is primarily used to send a JSON response back to an AJAX request, indicating that an error has occurred. This function is designed to encode data into a JSON format and automatically send it with the appropriate HTTP header.

When this function is called, it will send a JSON-encoded error message to the client. This can be useful in handling AJAX requests in WordPress, as it allows for a structured response format that can be easily interpreted by the client-side scripts. It simplifies the process of sending error responses and ensures the correct headers are set for the response.

The wp_send_json_error function also terminates script execution, which means that once this function is called, no other code will be executed afterwards. This can be beneficial in scenarios where an error is encountered and further script execution would be unnecessary or potentially harmful.

Parameters Accepted by the wp_send_json_error Function

The wp_send_json_error function in WordPress accepts three parameters, all of which are optional. These parameters are used to encode data as JSON, specify the HTTP status code, and set options for the JSON encoding process.

  • $data (mixed type): This parameter is optional and its default value is null. It is used to specify the data that will be encoded as JSON, printed, and then the function will stop executing.
  • $status_code (integer type): This is another optional parameter with a default value of null. It is used to define the HTTP status code that will be outputted.
  • $options (integer type): This parameter is also optional and its default value is 0. It is used to set options that will be passed to the json_encode() function.

Return Value of the wp_send_json_error Function

The wp_send_json_error function does not return any value. Once it finishes executing, it stops the script. This means that any code following a call to this function will not be executed.

Examples

How to Send a JSON Response with an Error Message

This is a basic example of using wp_send_json_error to send a JSON response with an error message.

if (!current_user_can('edit_posts')) {
 wp_send_json_error('You do not have permission to edit posts.');
}

In this snippet, we are checking if the current user has the capability to edit posts. If they do not, we send a JSON response with an error message stating “You do not have permission to edit posts”.

How to Send a JSON Response with an Error Message and HTTP Status Code

This example demonstrates how to use wp_send_json_error to send a JSON response with an error message and a HTTP status code.

if (!current_user_can('edit_posts')) {
 wp_send_json_error('You do not have permission to edit posts.', 403);
}

In this snippet, we are checking if the current user has the capability to edit posts. If they do not, we send a JSON response with an error message stating “You do not have permission to edit posts” and a HTTP status code of 403, indicating that the request was understood, but it has been refused due to insufficient permissions.

How to Send a JSON Response with an Error Message and Additional Data

This example shows how to use wp_send_json_error to send a JSON response with an error message and additional data.

if (!current_user_can('edit_posts')) {
 $data = array('user_id' => get_current_user_id(), 'message' => 'You do not have permission to edit posts.');
 wp_send_json_error($data);
}

In this snippet, we are checking if the current user has the capability to edit posts. If they do not, we send a JSON response with an error message stating “You do not have permission to edit posts”. Additionally, we also send the ID of the current user as part of the response data.

Conclusion

The wp_send_json_error function is a part of WordPress’s built-in Ajax handling mechanisms that allows developers to send a JSON response back to a client-side script with an error message. This function is typically used when an error occurs during an Ajax request, allowing the developer to return a JSON-encoded error message to the client side for further handling. By utilizing wp_send_json_error, developers can provide more informative and user-friendly error handling in their WordPress applications.

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