Make email addresses case insensitive

[codingjoe]

No description provided.

[codecov]

Codecov Report

Merging #5 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master     #5   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          12     13    +1     
  Lines         201    223   +22     
=====================================
+ Hits          201    223   +22

Impacted Files	Coverage Δ
mailauth/forms.py	100% <100%> (ø)	⬆️
mailauth/contrib/user/models.py	100% <100%> (ø)	⬆️
...th/contrib/user/migrations/0003_ci_unique_index.py	100% <100%> (ø)

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[SebastianKapunkt]

An option to not to create an extra index would be to always store the emails in lowercase and convert requests to lowercase before search.

[codingjoe]

@SebastianKapunkt very good point. Both methods may yield somewhat unexpected results. If one stores only lower case values, you are essentially overwriting the user input. That is ok though, I would do the same with phone numbers. What I don't like is that this method does not prevent wrong email addresses on a database level. The Index that I am adding has a unique constraint. It prevents you from adding duplicate email addresses on database level.

I believe the cleanest way in PostgreSQL is to use the CIEmailField. I will create a patch that does supports the optimal solution for all DB backends, even it requires a little more code on our side.

[SebastianKapunkt]

Good to go. Tested it manually in a new project.