Which field attributes only matter for schema generation?

When I discovered that TextField doesn't currently allow unique=True, it got me thinking... does it matter?

I don't use Tortoise to generate my schema, so there's no point setting field attributes that only matter for schema generation — other than as a form of documentation, which can be accomplished just as well in a comment.

So I did some skimming of the code and confirmed that index does, indeed, only matter for the sake of schema generation.

So, the next question is — which field attributes affect Tortoise behavior, and which only matter for schema generation? And might it be useful to describe that in the docs?

After some more skimming, I reached the following conclusions:

• Attributes that affect Tortoise behavior: auto_now, auto_now_add, default, generated, max_length, null, pk
• Attributes that only matter for schema generation: index, on_delete, unique[1]
• Attributes that only matter for schema generation, but are required by the field constructor so you have to specify them anyway: max_digits, decimal_digits

Note: I skipped a few that don't currently matter to me.

Would the authors like to comment on this topic, and also, would they appreciate a patch to add something like this to the docs?

[1] The exception is if configuring a ForeignKeyField or OneToOneField with to_field attribute pointed at a non-pk field. In that case, you do need to specify unique=True on the target field or Tortoise will complain.

No files or tests are named. Start by reviewing the field definitions and schema-generation documentation, focusing on the listed attributes and the TextField and relationship exceptions; verify the runtime-versus-schema distinction, then document it clearly, including the to_field/unique=True exception.