PHP's json_encode Failure with Single Quotes

In a scenario involving a PHP stdClass object ($post), the json_encode() function unexpectedly fails to encode the post_title property, resulting in a null value in the JSON output. Despite the apparent UTF-8 encoding of the database, it appears that the data retrieval process may not be correctly configured.

Cause: Incorrect Encoding

The JSON encoding issue stems from incorrect encoding of the single quote character in the post_title. Specifically, the character is encoded in Windows-1252, resulting in a hex value of 92, which is not a valid UTF-8 character.

Solution: Set Database Connection Encoding

To resolve this problem, it is necessary to set the database connection encoding to UTF-8. The method used depends on the API employed:

• MySQL: mysql_set_charset("utf8")
• MySQLi: mysqli_set_charset("utf8")
• PDO (PHP >= 5.3.6): charset parameter in connection string
• PDO (earlier versions): SET NAMES utf8

Additional Considerations

It's important to note that setting the connection encoding ensures that data retrieved from the database is properly encoded in UTF-8. However, if the data is stored in an incorrect encoding, such as Windows-1252, manual conversion through utf8_encode() or other means may be necessary.