Add collation option

[vsalvino]

Fixes #563

This change does not affect existing behavior if the collate option is not specified.

To test this out locally, e.g. in a Django project:

• Make sure you have MySQL or MariaDB C connector, and a C compiler installed.
• pip install git+https://github.com/vsalvino/mysqlclient.git
• Set your database connection as so:

DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.mysql",
        "HOST": "",
        "NAME": "",
        "USER": "",
        "PASSWORD": "",
        "OPTIONS": {
            "charset": "utf8mb4",
            "collation": "utf8mb4_unicode_ci",
        },
    }
}

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.10 🎉

Comparison is base (58465cf) 86.00% compared to head (fe0bb09) 86.10%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #564      +/-   ##
==========================================
+ Coverage   86.00%   86.10%   +0.10%     
==========================================
  Files           6        6              
  Lines         550      554       +4     
==========================================
+ Hits          473      477       +4     
  Misses         77       77              

Impacted Files	Coverage Δ
MySQLdb/connections.py	87.12% <100.00%> (+0.40%)	⬆️

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[vsalvino]

@methane do you have any opinions on this change? I do not want to publish a fork to PyPI, but we are in an impossible situation due to this behavior.

[vanschelven]

@methane any chance you could look at this?

[ViggieM]

@methane please take a look, as it is a pressing issue also for me

[vsalvino]

@methane checking on this again. It is causing major breakage and customer support issues for us. I have no choice but to publish a fork to PyPI and then change the Django and Wagtail documentation to direct users to the fork instead of the official package. I really DO NOT want to do this - relying on a fork is worse for everybody!

If you need help maintaining the package, by all means get in touch and I would be happy to volunteer. My email is salvino@coderedcorp.com.

[methane]

I'm very busy for now. I will take it in a month.

[methane]

Use collation, instead of collate.
https://dev.mysql.com/doc/connector-python/en/connector-python-connectargs.html

[methane]

For the record, I confirmed that MySQL Connector/Python does two queries too.

https://github.com/mysql/mysql-connector-python/blob/735322dbe0b453b01d3e52392cf364717b78bdb8/lib/mysql/connector/abstracts.py#L1113-L1117

[vsalvino]

In the future I would like to try changing the MariaDB and MySQL C libraries to accept collation when setting the character set, to reduce this to a single query, as I think that would be the most "proper" fix. However that would be a breaking API change or require adding a new API; so I imagine it would be unlikely to happen, or require a long time and much debate.

Thanks for your help.

[raisons]

When will the new version be released?

[vsalvino]

Update for anyone following, I published this change as mysqlclient-collate https://pypi.org/project/mysqlclient-collate/