✨ Use Pydantic for parameter validation

[svlandeg]

WIP: please don't comment/review yet, this will still change a lot.

Description

Make Pydantic a required dependency and rely on it for parameter validation.

• Type-specific stuff is in the new module param_types.py
• Pydantic-specific adapter stuff is in the new module adapters.py
• Coercion contracts are in the new module coercion.py

How to review this

• Probably read all of the below first 👇
• Note that _click/types.py and typer/_types.py are deleted
• First look at typer/param_types.py, then typer/adapters.py, then typer/coercion.py
• Look at the changes in typer/core.py
• Check all other changes in typer/*.py
• Check all changes in typer/_click/*.py
• Check all changes in the test suite & documentation

Extended/improved functionality

• More date time formats are now supported by default, instead of just the three [%Y-%m-%d|%Y-%m-%dT%H:%M:%S|%Y-%m-%d %H:%M:%S]
• Started moving towards a TyperParameter, not quite finished yet with some ugly imports from within _click but we'll deal with those in follow-up work

Tests with same behaviour on master

• Added test_bool_convert_valid to ensure that the "bool" conversion has remained the same for all kinds of inputs.
• Rewrote several tests to use Typer public API instead of internals

Breaking changes

(more or less in order of breakingness from most to least)

• Removed support for click_type and open bounds through min_open and max_open. This greatly simplifies the code base while still providing an alternative by setting parser instead.
• metavar variables now show up as the Python type lowercased and in <>, so "<str>" instead of "TEXT" and "<int>" instead of "INTEGER" etc.
• When not providing a default for DateTime, only one example is shown in the metavar column (%Y-%m-%d instead of [%Y-%m-%d|%Y-%m-%dT%H:%M:%S|%Y-%m-%d %H:%M:%S]) even though all three (and more) will work. It's not just those three anymore, so it felt arbitrary to show 3 out of n. We can decide to reverse the change and keep showing those three formats though.
• Validation error messages have changed from Click's to Pydantic's phrasing. This mostly requires updating test suites and otherwise shouldn't impact users too badly.
• Removed repr functionality of param.type. This wasn't really used except for the tests that were recently added in ➖ Vendor Click and streamline Typer's functionality and code base #1774.

Bug fixes (also breaking bwd compat)

• def main(age: int = typer.Option(15.3)) will now throw a validation error by Pydantic instead of int(15.3) converting it to 15. I consider this a bug fix instead of a regression, and have added a test test_int_rejects_float_default for it.
• Types are now inferred from the default if the parameter is untyped. Fixes Default value of `False` cast to `'False'` and is thus True #942, cf. new test test_default_infers_param_type.

Decision points

• _parse_cli_bool was created to ensure we still parse "" as False and to strip whitespace from something like " True ". This is just to mimic old Click behaviour. If we don't do this preprocessing (cleaner code base), the empty string and the non-stripped strings won't pass Pydantic validation and it would be slightly breaking.

AI Disclaimer

Cursor was used as a micro-managed junior. Every edit was reviewed & understood by me.

TODO

• Properly explain Pydantic dep in the docs
• Update the tutorial, focus on display of types & metavar
• Fix coverage

Checklist

• I added tests for the change.
• Coverage stays at 100%.
• The documentation explains the change if needed.

[svlandeg]

This test currently mimics master behaviour 100%.

[github-actions]

📝 Docs preview

Last commit 9c3ddd8 at: https://6603338f.typertiangolo.pages.dev

[github-actions]

This pull request has a merge conflict that needs to be resolved.