The mysql2date function in WordPress

This function is a part of WordPress and is used to convert a MySQL date string into a different format. It provides flexibility in converting dates by allowing the user to specify the desired format using a PHP date format string. The function also handles translation of the date and format string if needed.

Let's go through the code line by line:

 
/**
 * Converts given MySQL date string into a different format.
 *
 *  - \`$format\` should be a PHP date format string.
 *  - 'U' and 'G' formats will return an integer sum of timestamp with timezone offset.
 *  - \`$date\` is expected to be local time in MySQL format (\`Y-m-d H:i:s\`).
 *
 * Historically UTC time could be passed to the function to produce Unix timestamp.
 *
 * If \`$translate\` is true then the given date and format string will
 * be passed to \`wp_date()\` for translation.
 *
 * @since 0.71
 *
 * @param string $format    Format of the date to return.
 * @param string $date      Date string to convert.
 * @param bool   $translate Whether the return date should be translated. Default true.
 * @return string|int|false Integer if \`$format\` is 'U' or 'G', string otherwise.
 *                          False on failure.
 */

The code begins with a function declaration and a detailed description of the function. It explains the purpose of the function, the expected input parameters, and the return values. It also includes information about the historical usage of the function and the option for translation.

 
function mysql2date( $format, $date, $translate = true ) {

The function is named mysql2date, and it takes three parameters: $format, $date, and $translate. $format is the desired format of the date to be returned, $date is the MySQL date string to convert, and $translate is a boolean parameter indicating whether the returned date should be translated. By default, $translate is set to true.

 
    if ( empty( $date ) ) {
		return false;
	}

The function first checks if the $date parameter is empty. If it is, the function returns false, indicating a failure.

 
	$datetime = date_create( $date, wp_timezone() );

	if ( false === $datetime ) {
		return false;
	}

Next, the function uses the date_create() function to create a DateTime object from the given $date string, using the WordPress timezone (wp_timezone()). If the creation of the DateTime object fails, indicating an invalid date, the function returns false.

 
	if ( 'G' === $format || 'U' === $format ) {
		return $datetime->getTimestamp() + $datetime->getOffset();
	}

The function then checks if the $format parameter is either 'G' or 'U'. If it is, this means the user wants to retrieve the Unix timestamp with the timezone offset included. In this case, the function returns the sum of the DateTime object's timestamp and offset.

 
	if ( $translate ) {
		return wp_date( $format, $datetime->getTimestamp() );
	}

If the $translate parameter is true, indicating that translation is requested, the function calls the wp_date() function with the specified $format and the DateTime object's timestamp as arguments. The wp_date() function handles the translation and returns the translated date in the desired format.

 
	return $datetime->format( $format );

If translation is not requested, the function uses the format() method of the DateTime object to format the date according to the specified $format and returns the formatted date as a string.

The function covers various scenarios and provides flexibility in converting MySQL date strings into different formats, with optional translation support.

Example 1: Converting a MySQL date to a formatted date string

 
$date_string = '2023-06-22 10:30:00';
$formatted_date = mysql2date('F j, Y', $date_string);

echo $formatted_date; // Output: June 22, 2023

In this example, the function is used to convert a MySQL date string ($date_string) to a formatted date string using the format 'F j, Y'. The resulting formatted date is then echoed, displaying "June 22, 2023". This showcases how the function can be used to transform database-stored dates into human-readable formats.

Example 2: Getting a Unix timestamp with timezone offset

 
$date_string = '2023-06-22 10:30:00';
$timestamp = mysql2date('U', $date_string);

echo $timestamp; // Output: 1674377400

In this example, the function is used to convert a MySQL date string ($date_string) to a Unix timestamp using the format code 'U'. The resulting timestamp is then echoed, displaying "1674377400". This demonstrates how the function can be used to obtain Unix timestamps, which are commonly used for various calculations and comparisons.

Example 3: Formatting a date string with translation disabled

 
$date_string = '2023-06-22 10:30:00';
$formatted_date = mysql2date('l, F jS, Y \a\t g:i A', $date_string, false);

echo $formatted_date; // Output: Thursday, June 22nd, 2023 at 10:30 AM

In this example, the function is used to format a MySQL date string ($date_string) with a specific format 'l, F jS, Y \a\t g:i A'. The third parameter $translate is set to false, disabling translation of the formatted date string. The resulting formatted date is then echoed, displaying "Thursday, June 22nd, 2023 at 10:30 AM". This showcases how the function can be used to customize the date format and disable translation if needed.

Each example demonstrates a different aspect of the mysql2date function, such as formatting dates, obtaining Unix timestamps, and customizing the output with or without translation. These examples highlight the versatility of the function in handling various date-related requirements within a WordPress development context.

Example 4: Converting a MySQL date to a formatted date string with translation

 
$date_string = '2023-06-22 10:30:00';
$formatted_date = mysql2date('l, F jS, Y \a\t g:i A', $date_string);

echo $formatted_date; // Output: Thursday, June 22nd, 2023 at 10:30 AM

In this example, the function is used to convert a MySQL date string ($date_string) to a formatted date string using the format 'l, F jS, Y \a\t g:i A'. The resulting formatted date is then echoed, displaying "Thursday, June 22nd, 2023 at 10:30 AM". The function's default behavior of enabling translation is utilized here, allowing for localization of the formatted date string.

Example 5: Handling an empty date string

 
$date_string = '';
$formatted_date = mysql2date('F j, Y', $date_string);

if ($formatted_date === false) {
    echo 'Invalid date'; // Output: Invalid date
}

In this example, the function is called with an empty date string ($date_string). Since the date is empty, the function returns false to indicate failure. The code then checks if the returned value is false and displays the message "Invalid date". This demonstrates how the function can handle scenarios where the input date is invalid or missing.

Example 6: Using a different format code

 
$date_string = '2023-06-22 10:30:00';
$unix_timestamp = mysql2date('U', $date_string);

echo $unix_timestamp; // Output: 1674377400

In this example, the function is used to convert a MySQL date string ($date_string) to a Unix timestamp using the format code 'U'. The resulting Unix timestamp is then echoed, displaying "1674377400". This example showcases the ability to utilize different format codes to obtain specific representations of the date, such as Unix timestamps.

These additional examples further illustrate the versatility and usefulness of the mysql2date function in handling different date-related scenarios within WordPress development. They showcase features like translation, handling empty dates, and utilizing different format codes to cater to various requirements.

Example 7: Custom date format with translation

 
$date_string = '2023-06-22 10:30:00';
$formatted_date = mysql2date('M j, Y \a\t g:i a', $date_string);

echo $formatted_date; // Output: Jun 22, 2023 at 10:30 am

In this example, the function is used to convert a MySQL date string ($date_string) to a custom formatted date string using the format 'M j, Y \a\t g:i a'. The resulting formatted date is then echoed, displaying "Jun 22, 2023 at 10:30 am". This demonstrates how the function can be used to create specific date formats based on the desired representation.

Example 8: Handling an invalid date format

 
$date_string = '2023/06/22 10:30:00';
$formatted_date = mysql2date('F j, Y', $date_string);

if ($formatted_date === false) {
    echo 'Invalid date format'; // Output: Invalid date format
}

In this example, the function is called with a date string ($date_string) that is in an invalid format. Since the format does not match the expected MySQL date format, the function returns false to indicate failure. The code then checks if the returned value is false and displays the message "Invalid date format". This highlights how the function handles cases where the input date string format is incorrect.

Example 9: Formatting a date without translation and handling timezones

 
$date_string = '2023-06-22 10:30:00';
$formatted_date = mysql2date('F j, Y g:i a', $date_string, false);

echo $formatted_date; // Output: June 22, 2023 10:30 am

In this example, the function is used to format a MySQL date string ($date_string) without translation. The format used is 'F j, Y g:i a', which represents the format "June 22, 2023 10:30 am". The third parameter $translate is set to false to disable translation. This showcases how the function can handle time formatting and customization while considering timezones.

Example 10: Converting a MySQL date to a formatted date string in a different language

 
$date_string = '2023-06-22 10:30:00';
$formatted_date = mysql2date('F j, Y', $date_string);

// Assuming translation is set to a different language (e.g., Spanish)
$translated_date = translate_date_to_spanish($formatted_date);

echo $translated_date; // Output: 22 de Junio de 2023

In this example, the function is used to convert a MySQL date string ($date_string) to a formatted date string using the format 'F j, Y'. The resulting formatted date is then processed further using a custom translation function (translate_date_to_spanish) to translate it to a different language (e.g., Spanish). The translated date is then echoed, displaying "22 de Junio de 2023". This demonstrates how the function can be combined with custom translation logic to handle localization requirements.

These additional examples further showcase the flexibility and applicability of the mysql2date function in handling various date-related scenarios, including custom formats, handling invalid formats, timezones, and translations.

Here are some examples of common errors that can occur when using the mysql2date() function:

Invalid date format: If the $date parameter provided to mysql2date() is not in the correct MySQL date format (Y-m-d H:i:s), the function will return false. For example:

 
$format = 'F j, Y';
$date = '2021/05/20 12:30:45'; // Incorrect format
$result = mysql2date($format, $date);
var_dump($result); // Output: bool(false)

Empty date: If the $date parameter is empty, the function will return false. It's important to ensure that the $date parameter is not empty before calling mysql2date(). For example:
```
 
$format = 'F j, Y';
$date = ''; // Empty date
$result = mysql2date($format, $date);
var_dump($result); // Output: bool(false)
```
Invalid format specifier: If an invalid format specifier is provided in the $format parameter, the function may return unexpected results or false. It's crucial to use valid PHP date format specifiers when formatting the date. For example:
```
 
$format = 'Y-d-m'; // Incorrect format specifier
$date = '2022-05-20 12:30:45';
$result = mysql2date($format, $date);
var_dump($result); // Output: bool(false)
```
Translation error: If the $translate parameter is set to true, but the translation fails for some reason, the function may return unexpected results or false. Make sure that the translation functionality is properly set up and functioning correctly. For example:
```
 
$format = 'F j, Y';
$date = '2022-05-20 12:30:45';
$translate = true;
$result = mysql2date($format, $date, $translate);
var_dump($result); // Output: bool(false) (if translation fails)
```

It's important to handle these potential errors appropriately in your code and ensure that the input parameters are valid and correctly formatted to avoid unexpected results or failures.