Option to not install formatters

[jbmoorhouse]

Is your feature request related to a problem? Please describe.
For codebases that generate models only via generate_dynamic_models, an option to skip installing code formatters dependencies would be very useful 🙏

pip install datamodel_code_generator

currently installs isort and black which aren't required or dynamic models (maybe argcomplete also)?

[ilovelinux]

They are required because the generated code is formatted by default before being exported¹.

However, despite there's an option to disable formatting² and some use-cases that don't care about formatting (as the one you mentioned), there's no way to opt-out to formatters dependencies.

I think we should:

• Automatically disable formatting with a warning if:
  • Default formatters are not found.
  • No --formatters option is declared.
• Not raise the warning if formatting has been explicitly disabled.
• ⚠️ Move formatters to custom dependency.
• ⚠️ Make formatters installation opt-in.

Since the last two steps are breaking changes, they should be discussed broadly.

I'm not aware of a way to mark some optional dependency to being installed by default, but allowing the user to opt-out at installation time, as Rust does with feature flags. This would avoid the breaking change.

Footnotes

1. https://datamodel-code-generator.koxudaxi.dev/formatting/#available-formatters ↩

2. https://datamodel-code-generator.koxudaxi.dev/formatting/#disable-formatting ↩