易炼红调研全市正风肃纪监督工作

百度 有网友问妙华法师：有人说，合掌有16种含义，也有人说，合掌有25种含义的，到底哪个更准确？妙华法师：合掌虽然动作简单，但却蕴含了无限的含义。

This tutorial details how to automatically calculate and update new derivative metadata based on saved user metadata after a user submits data through a front-end form in WordPress. The article covers methods for correctly obtaining and updating user metadata, the importance of data type conversion, and the details of code implementation, aiming to help developers efficiently manage and maintain user-related information.

In WordPress development, we often need to process user data. Sometimes, a certain data submitted by the user (such as straight_speed) needs to be used as a basis to automatically calculate another derived data (such as straight_speed_percent) and save it. This not only improves the degree of automation of data processing, but also ensures data consistency. This article will guide you on how to implement this feature and point out common pitfalls and best practices.

Core implementation logic

The core process of realizing automatic calculation and update of user metadata includes the following steps:

1. Get current user information: Determine who the current user is.
2. Get basic metadata: Get the original user metadata value used for calculation from the database.
3. Perform calculations: perform mathematical operations on the obtained original value to obtain a new derivative value.
4. Update derivative metadata: Save the calculated new value to another metadata field of the user.

Key functions and precautions

In WordPress, operating user metadata mainly depends on the two core functions: get_user_meta() and update_user_meta(). Understanding their correct usage is the key to success.

1. Get user metadata: get_user_meta()

The get_user_meta() function is used to retrieve user metadata from a database. The basic syntax is:

 get_user_meta( int $user_id, string $key = '', bool $single = false )

• $user_id: Required . The user ID to get the metadata.
• $key: optional. The metadata key name to be retrieved. If empty, all metadata of the user will be returned.
• $single: optional. Boolean value. If set to true, only a single value is returned (even if there are multiple metadata of the same name in the database, only the first one is returned); if set to false, an array is returned. For scenarios where we usually store a single value, it should be set to true.

Common error prompts: In the original attempt, the developer may mistakenly pass the WP_User object returned by wp_get_current_user() directly as the $user_id parameter. This is incorrect. What get_user_meta() requires is the user ID, that is, $current_user->ID.

2. Data type conversion

User metadata retrieved from the database, even if the number is stored in the database, PHP may process it as a string. Before performing math operations, be sure to explicitly convert these strings to numeric types (such as integers (int) or floats) to avoid calculation errors.

For example, '100' * '2' will get 200 in PHP, but relying on this implicit conversion is not a good habit, especially if a string may contain non-numeric characters. Explicit conversions ensure the robustness of the code.

3. Update user metadata: update_user_meta()

The update_user_meta() function is used to update or add user metadata. The basic syntax is:

 update_user_meta( int $user_id, string $meta_key, mixed $meta_value, mixed $prev_value = '' )

• $user_id: Required . The user ID to update the metadata.
• $meta_key: Required . The metadata key name to be updated.
• $meta_value: Required . The metadata value to set.
• $prev_value: optional. Old metadata value. If specified, updates are only made if the existing metadata matches this value. Usually not used.

Common error tips: In the original attempt, the developer might mistakenly wrap the variable $straight_acceleration_percent_value in quotes so that it is treated as the string literal '$straight_acceleration_percent_value' rather than the value of the variable. This is incorrect. The variable name should be passed directly when updating.

Sample code implementation

Combining the above points, the following is the correct code snippet to implement user metadata calculation and update. This code assumes that you have successfully saved the straight_speed value through a front-end form such as the Elementor Pro form, and this calculation logic will be triggered after the straight_speed value is updated.

 <?php /**
 * After the user metadata is updated, the derivative metadata is automatically calculated and updated.
 *
 * @param int $user_id User ID.
 */
function calculate_and_update_derived_user_meta( $user_id ) {
    // Get the current user object (although the incoming $user_id is used here directly, if you need to get the current logged-in user inside the function, wp_get_current_user() is still useful)
    // $current_user = wp_get_current_user();
    // $user_id = $current_user->ID; // Make sure to use the correct user ID

    // 1. Get the underlying metadata 'straight_speed'
    // Note: The first parameter of get_user_meta should be the user ID, and the third parameter is set to true to obtain a single value $straight_speed = get_user_meta( $user_id, 'straight_speed', true );

    // 2. Check whether the underlying value exists and is valid if ( $straight_speed !== '' && $straight_speed !== false ) {
        // 3. Perform calculation // Be sure to convert the obtained string value into an integer or a floating point number and then calculate to ensure accuracy $straight_speed_percent_value = (int)$straight_speed * 100;

        // 4. Update derivative metadata 'straight_speed_percent'
        // Note: The third parameter of update_user_meta should be the variable itself, rather than the variable name updated_user_meta wrapped in quotes ( $user_id, 'straight_speed_percent', $straight_speed_percent_value );
    }
}

// Mount this function to the appropriate WordPress hook// If your Elementor Pro form triggers a specific action when submitting, you can mount to that action.
// Common hooks include 'profile_update' (triggered when user profiles are updated) or custom submission hooks for Elementor forms.
// Assume that the Elementor Pro form will trigger a similar hook for 'elementor_form_submit_success' after submitting it,
// Or more generally, if the form updates the user profile, you can use the 'profile_update' hook.
add_action( 'profile_update', 'calculate_and_update_derived_user_meta', 10, 1 );

// If the Elementor Pro form has its specific successful submission hook, for example:
// add_action( 'elementor_pro/forms/new_record', 'calculate_and_update_derived_user_meta_for_elementor', 10, 2 );
// function calculate_and_update_derived_user_meta_for_elementor( $record, $handler ) {
// // Suppose you can get the user ID and the submitted straight_speed value from $record // // $user_id = get_current_user_id(); // or parse from $record // // $straight_speed_data = $record->get_field( 'straight_speed' );
// // calculate_and_update_derived_user_meta( $user_id ); // Call the main function // }

?>

Code placement: You can add the above code to your theme's functions.php file, or, more recommended, encapsulate it in a custom plugin.

Summarize

By correctly understanding and using the get_user_meta() and update_user_meta() functions, and paying attention to the details of data type conversion and variable references, you can easily implement the ability to automatically calculate and update user metadata after a WordPress front-end form is submitted. Choosing the right WordPress hook (such as profile_update or specific form submission hook) to trigger your calculation logic will ensure that the data is kept up to date and accurate every time the user updates the relevant information. This not only improves the management efficiency of user data, but also lays a solid foundation for subsequent data analysis and function expansion.

The above is the detailed content of Guide to calculate and automatic update of user metadata after submission of WordPress front-end form. For more information, please follow other related articles on the PHP Chinese website!