Describe the bug
I would like to set a field passed from a $ref (let's say A) as required. If I simply put it in the required on my schema (let's say B), then I get some import errors.

If I follow another syntax, like here, I get no import error but the field is simply not required

To Reproduce
Create a simple folder <my-folder> and place these two files:

---
type: object
title: A
properties:
  a_field: 
    type: string
    enum: [base_schema]
    default: base_schema

---
type: object
title: B
allOf:
  - A
required:
  - a_field

Of course, here I could simply set a_field as required directly in A but this is just a basic example.

Or this one with the other syntax tried:

---
type: object
title: B
allOf:
  - A
    required:
      - a_field

Command to generate models
Run:
datamodel-codegen --input-file-type jsonschema --input <my-folder> --output <output-folder>

For some reason, I cannot make it work with yaml as input-file-type ...

Expected behavior
I expect the B model to be generated like this (or something alike):

from __future__ import annotations

from enum import Enum

class AField(Enum):
    base_schema = 'base_schema'

class B():
    a_field: AField = 'base_schema'

We could also imagine importing AField from file A

Instead I either get this (with the import errors):

from __future__ import annotations

from .a import A


class B(A):
    a_field: AField

Or this one with the field not required:

from __future__ import annotations

from .a import A


class B(A):
    pass

Version:

• OS: Windows + Linux
• Python version: 3.11
• datamodel-code-generator version: 0.25.1