Pydantic how to create a model with required fields and dynamic fields?

Question

I have a dynamic json like:

{
  "ts": 1111111,  // this field is required
  ...             // others are dynamic
}

The fields are all dynamic except ts. E.g:

{"ts":111,"f1":"aa","f2":"bb"}

{"ts":222,"f3":"cc","f4":"dd"}

How to declare this model with Pydantic?

class JsonData(BaseModel):
    ts: int
    ...  # and then?

Equivalent to typescript:

interface JsonData {
  ts: number;
  [key: string]: any;
}

Thanks.