fastapi pydantic nested models

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My view models below:

class EnvContainersStatusResponse(BaseModel):
    description: str = Field(...)

    class Config:
        orm_mode = True
        allow_population_by_field_name = True


class EnvContainersResponse(BaseModel):
    container_name: str = Field(alias='_name')
    container_status: EnvContainersStatusResponse

    class Config:
        orm_mode = True
        allow_population_by_field_name = True


class EnvResponse(EnvBase):
    env_id: str = Field(alias='environment_name')
    container_collection: List[EnvContainersResponse] = Field(alias='compute_node_containers')

    class Config:
        orm_mode = True
        allow_population_by_field_name = True

my response is like below

{
  "environment_name": "somenewenv",
  "compute_node_containers": [
    {
      "_name": "compute001",
      "container_status": {
        "description": "online"
      }
    }
  ]
}

question: how i can flatten my response model to have below:

want eliminate another dict and have only key value like “container_status”: “online”

{
  "environment_name": "somenewenv",
  "compute_node_containers": [
    {
      "_name": "compute001",
      "container_status": "online"
      
    }
  ]
}

[shrutikaponde]

@aaronstephenson, I solved this by adding response_model_by_alias.

@router.get("/",
            response_model=List[schemas.Command],
            response_model_by_alias=False)

[paloderosa]

@grillazz I actually came up today to the need to implement this functionality in a many-to-many relationship. Here is my implementation of the first proposal. I will assume that you are using SQLAlchemy for ORM, that you are traversing the entities relationships through relationship model attributes and that you have initialized the declarative Base class somewhere.

import functools
from typing import Any, List

from pydantic import BaseModel, Field
from pydantic.utils import GetterDict
from sqlalchemy import Column, String
from sqlalchemy.orm import relationship


# implementation of a recursive getattr
# taken from https://stackoverflow.com/a/31174427
def rgetattr(obj, attr, *args):
    def _getattr(obj, attr):
        return getattr(obj, attr, *args)
    return functools.reduce(_getattr, [obj] + attr.split('.'))


class NestedGetterDict(GetterDict):
    def __getitem__(self, key: str) -> Any:
        try:
            return rgetattr(self._obj, key)
        except AttributeError as e:
            raise KeyError(key) from e

    def get(self, key: Any, default: Any = None) -> Any:
        return rgetattr(self._obj, key, default)


class Container(Base):
    __tablename__ = 'container'
    ...
    container_status = relationship("ContainerStatus", lazy='joined')

class ContainerStatus(Base):
    __tablename__ = 'container_status'
    ...
    description = Column(String, nullable=False)


class EnvContainersResponse(BaseModel):
    container_name: str = Field(alias='_name')
    container_status: str = Field(alias='container_status.description')

    class Config:
        orm_mode = True
        allow_population_by_field_name = True
        getter_dict = NestedGetterDict


class EnvResponse(EnvBase):
    env_id: str = Field(alias='environment_name')
    container_collection: List[EnvContainersResponse] = Field(alias='compute_node_containers')

    class Config:
        orm_mode = True
        allow_population_by_field_name = True

This should result in what you are looking for.