From the pydantic docs I understand this:

import pydanticclass User(pydantic.BaseModel):id: intname: strclass Student(pydantic.BaseModel):semester: int# this works as expected
class Student_User(User, Student):building: strprint(Student_User.__fields__.keys())
#> dict_keys(['semester', 'id', 'name', 'building'])

However, when I want to create a similar object dynamically (following the section dynamic-model-creation):

# this results in a TypeError
pydantic.create_model("Student_User2", __base__=(User, Student))

I get:

TypeError: metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases

Question: How to dynamically create a class like Student_User

Its not the answer to the original question, but if you are like me and all you care about is having a model which holds fields of other models, this should be a solutions.

Student_User = pydantic.create_model("Student_User", **{**{key: (value.type_, value.default) for key, value in User.__fields__.items()},**{key: (value.type_, value.default) for key, value in Student.__fields__.items()},**{"building": (str, '')},
})

Essentially, we are dynamically creating a new pydantic model and we are setting its fields to be the fields of our other models plus an additional custom field.

Note: OP included these lines in his question:

print(Student_User.__fields__.keys())
#> dict_keys(['semester', 'id', 'name', 'building'])

So, my guess is that his end goal was copying the fields from the other models and having a model created from multiple bases was just a method of achieving it.