🐛 Handle hash based frontend routing

[Viicos]

Fixes #3362
Linked to open-formulieren/open-forms-sdk#586

This adds a new query parameter redirect_path, that the frontend sdk should special case on window.onload to redirect to the correct path based on the configured routing method.

[sergei-maertens]

I think I'd prefer a query param _action=foo rather than redirect_path so that we can decouple the actions from the actual client-side URLs.

We only need to synchronize the list of literal action names then and our backend and frontend become more agnostic of each other.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (141529b) 95.97% compared to head (a6d6282) 95.96%.

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Files	Patch %	Lines
src/openforms/frontend.py	91.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3574      +/-   ##
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- Coverage   95.97%   95.96%   -0.01%     
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  Lines       21893    21892       -1     
  Branches     2531     2533       +2     
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  Misses        611      611              
- Partials      271      272       +1     

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[Viicos]

One thought that I had: The number of action_args arguments passed in get_frontend_redirect_url could be validated depending on the action used, but this is only beneficial for the developer. overloads could be useful but a bit overkill and cumbersome.

I took a look at the possible redirects from the backend and it seems to be all covered. There're still some old URL formats in tests but I think they mimic what is emitted by the SDK (e.g. in authentication with the next URL).

[sergei-maertens]

so right now with hash based routing, this would result in a URL like example.com/myform?time=...&submission_uuid=...#/afspraak-annuleren while it should be:

example.com/myform#/afspraak-annuleren?time=...&submission_uuid=... - i.e. the time & submission_uuid really should be _action_params as they're directly related to the action.

[Viicos]

There are still some failing tests, mainly because:

open-forms/src/openforms/frontend.py

Lines 23 to 27 in feb37d3

	if action_params:
	# furl takes care of quoting the query parameters if necessary, so we don't use urllib.parse.urlencode
	_query["_of_action_params"] = urllib.parse.urlencode(action_params)
	return f.add(_query).url

This performs a first round of URL encoding, e.g. query={"_of_action_params": "time=00%3A00"} (with action_params={"time": "00:00"})

Then furl does a second round of URL encoding, resulting in ?_of_action_params=time%3D00%253A00:

• = is correctly encoded as %3D
• % was incorrectly encoded as %25

Another option would be to have query=urllib.parse.urlencode(json.dumps(action_params))

Edit: in fact this might be fine

[sergei-maertens]

good to have it (and keep it!), but let's also do the data migration where we clean/sanitize the URLs for existing submissions.

[Viicos]

Added the migration, not sure if it covers all cases? Let me know if you think some other cases should be taken into account into this migration