How to use include/exclude with lists?

Question

When using include/exclude with nested structures, how do I specify what to include/exclude when the child model is a list?

Where the child is a single element and I only want the id of that element, I know from the docs that I can do:

A.dict(include={"id": ..., "child": {"id": ...}})

Where the child is a list of a model, and I only want a single element of that list, and only the id of that element, I know from reading #640 that I can do:

A.dict(include={"id": ..., "children": {0: {"id": ...}}})

But what is the syntax (assuming there is a syntax) to specify that I want all children, but only the “id” field for all children?

Also, what would be the syntax (again, assuming it is possible) to specify that for the Parent, I want all top level attributes, but only the “id” of the nested attributes?

Thank you for your help and for the library.

Please complete:

• OS: Linux
• Python version import sys; print(sys.version): 3.7.4
• Pydantic version import pydantic; print(pydantic.VERSION): 1.0

Please read the docs and search through issues to confirm your question hasn’t already been answered.

Where possible please include a self contained code snippet describing your question:

from __future__ import annotations
from typing import List, Optional

from pydantic import BaseModel, VERSION as pydantic_version
from dataclasses import dataclass


class Parent(BaseModel):
    id: int
    child: Child
    children: List[Child] = []

    class Config:
        orm_mode = True

class Child(BaseModel):
    id: int
    age: int

    class Config:
        orm_mode = True

Parent.update_forward_refs()

@dataclass
class OrmChild:
    id: int
    age: int

@dataclass
class OrmParent:
    id: int
    children: List[OrmChild]
    child: OrmChild

c1 = OrmChild(1, 12)
c2 = OrmChild(2, 7)
c3 = OrmChild(3, 2)
a = OrmParent(id=1, children=[c1, c2, c3], child=c1)

A = Parent.from_orm(a)

print(A.dict(
# WHAT GOES HERE?!
)

[parchd-1]

I can only assume what other people would commonly require but I think

But what is the syntax (assuming there is a syntax) to specify that I want all children, but only the “id” field for all children?

This is something I expect people to want quite commonly - more commonly than wanting to have just the _n_th element of a list, which was one of the test cases you discussed when developing the syntax.

Also, what would be the syntax (again, assuming it is possible) to specify that for the Parent, I want all top level attributes, but only the “id” of the nested attributes?

The reason I want this is for an API, with nested models, some of which are quite large, I only want to send to the front end the top level attributes and a subset of children elements to be fetched if required. I think this is also quite commonly needed in APIs, but it is not my area of expertise.

[wendersonj]

when trying to exclude a bool , i got the message:

  File "pydantic\main.py", line 779, in pydantic.main.BaseModel._get_value
  File "pydantic\utils.py", line 479, in pydantic.utils.ValueItems.__init__
TypeError: Unexpected type of exclude value <class 'bool'> ```

answering my question: the error occurs in pydantic version 1.8.2. When updated to version 1.9.0 everything went fine ! cheers