Create a class of type List with restricted element type

[debakarr]

Hi,

First of all thanks for the great package!

Now coming to the question, what I wanted to do is:

• Have a model class (Say class User).
• Now have one more model class that supports List operations such as iteration as well as append (say class UserList).
• Have one more class that supports Map operation like add or get (say class MapUserList).

I have the following code for this:

from typing import List, Dict

from pydantic import BaseModel, validate_arguments


class User(BaseModel):
    id: int
    name: str


class UserList(BaseModel):
    userList: List[User] = list()

    @validate_arguments
    def append(self, user: User):
        self.userList.append(user)

    def __getitem__(self, i):
        return self.userList[i]

    def __len__(self):
        return len(self.userList)


class MapUserList(BaseModel):
    mapping: Dict[str, UserList] = dict()

    @validate_arguments
    def addTo(self, key: str, value: User):
        theList = self.mapping.get(key)
        if theList is None:
            theList = UserList()
        theList.append(value)
        self.mapping[key] = theList


mapping = MapUserList()
mapping.addTo("Group A", User(name="John", id=1))
mapping.addTo("Group A", User(name="Marry", id=2))
mapping.addTo("Group A", User(name="Shawn", id=3))
mapping.addTo("Group B", User(name="Billy", id=4))
mapping.addTo("Group B", User(name="Bob", id=5))

jsonStr = mapping.json()  # Serialize
mappingDeSerialized = MapUserList.parse_raw(jsonStr)  # De-Serialize

I want to know if there is a way in Pydantic using which I can eliminate writing those append method in UserList class or addTo in MapUserList class.