Individual event colours do not sync

[Sorrel-kun]

I'm currently looking into DAVx5 and Simple Calendar due to needing to set up a new phone and wanting to migrate away from stock google apps, a first step in a long journey of de-googling my life.
https://github.com/SimpleMobileTools
https://github.com/bitfireAT/davx5-ose

I have a google calendar.
The calendar has a colour set (purple), which all events default to. This is synchronised correctly.
I use colours for individual events within the calendar to differentiate certain things (blue).
These events' colours do not seem to be synchronised correctly, ie. they still show purple, but should be blue.

I am trying to troubleshoot whether this issue originates from DAVx5 or the Simple Calendar.

These suggest that event colours should be working in DAVx5:
https://www.davx5.com/faq/change-calendar-color/
https://manual.davx5.com/settings.html#caldav
https://manual.davx5.com/accounts_collections.html#refreshing-the-collection-list

The settings for the account are, I believe, correct:
Manage calendar colours - true (calendar colours are reset at each sync)
Event colour support - true (event colours are synced)

When loading up the calendar in Simple Calendar, nothing crashes; it all appears to work.
The only thing that does not synchronise are events with colours that are not the same as the calendar colour, and even then, it's just their colour that doesn't come over.

These suggest that event colouring should be working in Simple Calendar:
SimpleMobileTools/Simple-Calendar#360
SimpleMobileTools/Simple-Calendar#2028
SimpleMobileTools/Simple-Calendar#2041
SimpleMobileTools/Simple-Calendar#2062

So I'm at a bit of a loss about what to do now.
Has anyone else seen this behaviour in action?
Got any advice?

Thanks all,
Sorrel

[ArnyminerZ]

Hi, first of all, I recommend that you stop using Simple Mobile Tools and start using Fossify. They are exactly the same apps, but Simple Mobile Tools was acquired by a company with very doubtful security policies, and that's why Fossify was created. You can access its repo at https://github.com/FossifyOrg/Calendar

I can't confirm whether it actually works, since Nextcloud's support for per-event colors seems to be broken, or at least doesn't work correctly for me. But I think everything should work fine, it's updating correctly, at least on my device, and I think to the server as well.

Which server are you using? Are you sure it supports per-event colors?

[exstntlmsnthrp]

I can't confirm whether it actually works, since Nextcloud's support for per-event colors seems to be broken, or at least doesn't work correctly for me.

I believe it is still broken. I cannot get per-event colours to work on Nextcloud 30 at the moment (unless I'm doing something incorrectly). I have to use multiple calendars to differentiate colours for events.

[Sorrel-kun]

Hi, first of all, I recommend that you stop using Simple Mobile Tools and start using Fossify.

Alright, that's done.
Still observing the same lack of event-specific-colour behaviour.
(Since you've said Fossify is basically the same code, this is not surprising.)

Which server are you using? Are you sure it supports per-event colors?

It's a google calendar, so I'm guessing it's a google server. The Address (URL) of the calendar starts with https://apidata.googleusercontent.com/caldav/v2/
I know google calendar definitely supports per-event colours within its own google ecosystem.
For example, I can set an event's colour via the google web calendar interface (ie. just going to calendar.google.com in any desktop web browser), and that change will be reflected in, eg. the google calendar app on my phone.

This is my first time attempting to use a non-google calendar app though.
I don't currently know anything about the CalDAV protocol, so it's conceivable to me that the server fails to properly send per-event colour info, to places that exist outside of the google ecosystem.
If that's the case, I don't know how I'd go about debugging that.

I did find this:
https://developers.google.com/calendar/caldav/v2/guide
Which led me to this:
https://developers.google.com/calendar/api/v3/reference/events#resource-representations
Which has a colorId attribute/property, so presumably, yes, the server does support per-event colours.

[exstntlmsnthrp]

Not to be pedantic, but I've seen some arguments that the Fossify (and Simple before it) calendar is not a true calendar app. Rather it simply reads and displays calendar data from other services and because it previously did not have the ability to create it's own local calendar. I'm not sure whether I agree or disagree, personally; but, I digress.

Regardless, after Simple was purchased, I moved to using Etar (GitHub or F-Droid) on my device and I've been very happy with it. It works very well with DavX⁵ and the app does support per-event colours; even if the Nextcloud implementation of that is broken.

[ArnyminerZ]

I've seen some arguments that the Fossify (and Simple before it) calendar is not a true calendar app.

Technically, in Android, calendar apps are not "true calendar apps" as you say. Android has a shared calendar (and contacts) database, from which all apps can obtain data; that's where you grant access when an app asks for "calendar permission" or "contacts permission". You can take a look at the developer guide here if you are curious.

So technically, as you have said, no, Fossify Calendar is not a "true calendar app", but you can also say the same about other calendar applications, they at most create one new calendar in this shared database, or in the case of Google Calendar or Outlook for example, they have their own synchronization protocols that add all the data from their respective servers to this database, which is exactly what DAVx⁵ does.

I hope this information is helpful.

Also, we can really recommend using Etar or aCalendar+ for example. Actually most calendar apps have their own way of setting colors when not supported by the provider, for example by adding the color to the description, that's probably what Etar is doing. However, feel free to use whatever calendar app suits you better.

[ArnyminerZ]

@Sorrel-kun I've done a quick google search, and I couldn't find any information regarding the supported features by Google's CalDAV API. However, by asking Gemini I got this answer:

Regarding the VEVENT COLOR property, it's highly unlikely that Google Calendar's CalDAV API supports it. This feature is often specific to individual calendar applications and isn't a standard part of the CalDAV protocol.

Which I think is not even true, because COLOR is a standard property, but I guess it was introduced in a future patch, and since it's not a "super-important feature" most providers don't support it.

That's almost everything that I can say. See also my comment from before regarding custom color implementations by specific apps, but to sum up, if the calendar provider doesn't support the COLOR property for VEVENT we can't really do much. There are this workarounds for the apps, but it's really unlikely that they will work both on the website and the app. Sorry for the inconvenience.

[exstntlmsnthrp]

Technically, in Android, calendar apps are not "true calendar apps" as you say.

Thank you. I was unaware of that. I've learnt something new today.

You can take a look at the developer guide here if you are curious.

Absolutely. Thank you for sharing.

So technically, as you have said, no, Fossify Calendar is not a "true calendar app", but you can also say the same about other calendar applications, they at most create one new calendar in this shared database, or in the case of Google Calendar or Outlook for example, they have their own synchronization protocols that add all the data from their respective servers to this database, which is exactly what DAVx⁵ does.

I hope this information is helpful.

Yes, very helpful. Thank you for sharing. It gives me a better understanding of how the backend is working.