This is the same problem that we had in MDL-52486. When the language
pack with multiple underscores (such as "en_us_k12") is selected, the
html root element's "lang" attribute is set to
<html lang="en-us-12" ...>
which we then map back to the Moodle lang code using the JS function
replace().
What was missed in MDL-52486 was that when replacing a value (and not a
regular expression), only the first instance of the value is replaced.
So the value "en_us-k12" was sent as the lang parameter for the
core_string, which is invalid PARAM_LANG value and the exception was
thrown.
In case of the user_date.js, there was no actual problem experienced and
probably there is none as the language code is used as a cache key
rather than a PARAM_LANG parameter. But we are changing it too for
consistency.
In some cases, underscores in lang codes get replaced with dashes
which causes some JavaScript to be unhappy. This patch simply reverse
the underscore to dash replacement on the JS side.
Now the db/service.php array can contain these extra keys to provide information
on how a webservice may be called:
'ajax' => true (Default is false)
Replaces the xx_is_allowed_from_ajax callback.
'loginrequired' => false (Default is true)
Means that this webservice can be called through lib/ajax/service-nosession.php
which sets NO_MOODLE_COOKIES to true (faster). This is only safe for webservices returning
static public data (e.g. get_string).
