Why is `json_encode()` returning null values for properties with single quotes?

JSON Encoding Failure: Resolving Discrepancies with Single Quotes

Developers frequently encounter silent failures when attempting to encode objects using PHP's json_encode() function. In this context, a user encountered an issue where encoding a stdClass object resulted in null values for properties containing single quotes.

Analysis

Upon examining the issue, it was discovered that the underlying cause was the inability of json_encode() to correctly handle characters outside the ASCII range. The single quote character, represented as x92 in a hex dump, was particularly problematic.

Solution

To resolve the issue, it is essential to ensure that the data being encoded is properly encoded in UTF-8. This can be achieved by setting the MySQL connection encoding appropriately, dependent on the API employed:

• Old (Deprecated) API: mysql_set_charset("utf8")
• mysqli: mysqli_set_charset("utf8")
• PDO: Add the charset parameter to the connection string or execute SET NAMES utf8 if using PHP 5.3.6 or earlier.

Alternative Approach

An alternative solution can involve using utf8_decode() to convert the text into a format that is correctly encoded. However, this may not always yield the desired result, as it assumes that the text is encoded in ISO-8859-1.

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