Allow markdown rendering to handle no-ops

[bunsenmcdubbs]

When creating new events, the client sends off an errant request to the server to render markdown that isn't yet there (sends a request directly to http://localhost:8080/admin/api/utils/render-commonmark)

GET /admin/api/utils/render-commonmark

This causes an error on the server because the endpoint expects an query parameter text.

00:41:04.854 [qtp51376124-21] ERROR alfio.controller.ControllerExceptionHandler - unexpected exception
org.springframework.web.bind.MissingServletRequestParameterException: Required String parameter 'text' is not present

This should be a simple fix on both client and server side. I can take care of it in a PR.

[cbellone]

thank you 👍

[bunsenmcdubbs]

I decided to leave the server alone because it makes sense to fail when there is no text param. Do you think I should make the text parameter optional and return an empty string when it isn't provided? @cbellone

[bunsenmcdubbs]

Pressing the "Preview" button in the displayCommonmarkPreview directive will have nothing show up when there is no text (provided to the directive -- there maybe text in the input but ng-minlength can eliminate any input).

I added the default value for the renderCommonmark endpoint in the previous commit (929b246) but I'm not sure if that is actually good. On second thought it might be better to have the API "fail fast" when there is no text parameter provided at all (different from an empty string text parameter which should always work regardless).

[cbellone]

Hi @bunsenmcdubbs,

I would suggest the following:

1. intercept the exception at Spring controller level, see https://github.com/exteso/alf.io/blob/master/src/main/java/alfio/controller/api/AttendeeApiController.java#L56 (the exception to be caught here could be org.springframework.web.bind.MissingServletRequestParameterException) and return an HTTP 400 (bad request) status. That would be nice to have.
2. add a check in the Angular directive https://github.com/exteso/alf.io/blob/master/src/main/webapp/resources/js/admin/directive/admin-directive.js#L560 in order to call the server API only if needed (and doing nothing otherwise)

how does it sound?

[bunsenmcdubbs]

Sounds good. I created PR #141

[syjer]

merged! thank you!