PHP 8.3 adds a new function named json_validate that returns true or false whether the given string is a valid JSON string.

Prior to PHP 8.3, the only way to determine if a given string is a valid JSON string was to attempt to decode it, and see if any errors were emitted. The new json_validate function uses the same underlying JSON parser PHP uses, but consumes less memory and processing as json_decode only analyzes the string without constructing any decoded value.

Applications that have strong measures to prevent invalid JSON strings from being processed may not find the new json_validate function useful, because a json_validate call immediately followed by a json_decode can slightly increase the execution time as the JSON string is analyzed twice, and there is a higher chance of the input JSON string being valid JSON in the place.

Applications that accept user-provided JSON, or connect remote JSON APIs may find the best use of the new json_validate, because there is a significant chance of encountering invalid JSON strings.

Required

1. No change is required but we may want to look at using the new json_validate in places where we currently perform poor-man's validation
2. If we do opt to use the new validation method, we must perform a PHP version check and raise a new MDL to remove the old method when we cease support for PHP 8.2
3. If we do make change, it will be to master only.