I have several string fields:

class Object(BaseModel):
  color: str
  shape: str

I would wish to validate the value of these fields, since they have a definite format, but the set of values is not finite, so an enum does not work.

In this example:

• color can be not only "red" or "blue" but also e.g. hex codes #ffc8a0, …
• shape can be not only "square", "cube", "hexagon" but also "9-gon", "135-gon", …

So I would want to have

class Color(BaseModel):
   ...

class Shape(BaseModel):
   ...

class Object(BaseModel):
   color: Color
   shape: Shape

But if I have

class Color(BaseModel):
   name: str | None
   hex: str

I still want to be able to parse "red" and get Color(name="red", hex="#ff0000") instead of having to parse {"name": "red", "hex": "#ff0000"}.