Errors handling in web services
From MoodleDocs
Exceptions
Format
Exceptions are caught by the server that generate its own error format. For example in REST:
<?xml version="1.0" encoding="UTF-8"?>
<EXCEPTION class="invalid_parameter_exception">
<MESSAGE>Invalid parameter value detected</MESSAGE>
<DEBUGINFO></DEBUGINFO>
</EXCEPTION>
All exceptions contain a translated message + debuginfo.
When to send an exception
- DB WRITE functions must rollback when an exception is raised. We usually throw back the exception to the server.
Warning messages
Format
/**
* Creates a warnings external_multiple_structure
* @return external_multiple_structure
* @since Moodle 2.3
*/
private static function warnings() {
return new external_multiple_structure(
new external_single_structure( array(
'messageid' => new external_value(PARAM_INT, 'message id is a string that can be parsed by the client developer
to find out what kind of error is it. For example: 'userdoesntexist),
'debugmessage' => new external_value(PARAM_TEXT, 'a not translated debug message to help the client developer to
know straight away what is the issue'),
'elementsdescription' => new external_value(PARAM_TEXT, 'explaination of the element. For example:
"elements is a list of failing user id" or
"elements is an array(courseid, contextid, userid)" or
"elements is a list of couple course/category like (courseid1, categoryid1, courseid2, categoryid2...)" '),
'elements' => new external_multiple_structure( new external_value(PARAM_RAW, 'an element - it could be useful
to let the client developer implements some automatic code fixing on the client side')),
), 'warning'), 'list of warnings'
);
}
When to send a warning
TODO