I’m using @model_validator along with model_validate to check if values match child class:

sample request payload:

{
  "name": "BC",
  "connectorType": "SNOWFLAKE",
  "productName": "bc",
  "secretArn": "foobararn",
  "warehouse": "foobarwarehouse",
  "tableSchema": "foobarschema",
  "database": "bardatabse"

}

Snowflake connector class:

class SnowflakeConnector(SpotApiBaseModel):
    """Snowflake Connector."""
    model_config = ConfigDict(from_attributes=True)

    secretArn: str = Field(description="AWS secret arn")
    warehouse: str = Field(description="Snowflake warehouse. Required for connector type: SNOWFLAKE")
    database: str = Field(description="Database name. Required for connector type: SNOWFLAKE")
    tableSchema: str = Field(description="Database table schema. Required for connector type: SNOWFLAKE")


class ConnectorInterface(BaseConnector):

    @model_validator(mode='before')
    def check_allowed_products(cls, values):
        connector = values.get('connectorType').lower()
        if connector == "s3":
            S3Connector.model_validate(values)
        elif connector == "snowflake":
            SnowflakeConnector.model_validate(values)

When any of the required fields is missing I’m getting expected response:

"Field required: ('body', 'database')"

but when all fields are there, instead of getting correct response I’m getting this:

"Input should be a valid dictionary or object to extract fields from: ('body',)"

Exception:

{"time": "2024-06-18T10:46:45.641Z", "l": "ERROR", "rid": "2558770a-66ff-4da0-b8a2-977afc5043e6", "org": "", "act": "", "message": "An error occurred: [{'type': 'model_attributes_type', 'loc': ('body',), 'msg': 'Input should be a valid dictionary or object to extract fields from', 'input': None, 'url': 'https://errors.pydantic.dev/2.6/v/model_attributes_type'}]", "component": {"name": "/app/common/exceptions/base_exception_handler.py", "version": "0.1.3"}, "exception": "Traceback (most recent call last):n  File "/Library/Caches/pypoetry/virtualenvs/service-Qx3_L5c2-py3.12/lib/python3.12/site-packages/starlette/middleware/exceptions.py", line 68, in __call__n    await self.app(scope, receive, sender)n  File "/Library/Caches/pypoetry/virtualenvs/service-Qx3_L5c2-py3.12/lib/python3.12/site-packages/fastapi/middleware/asyncexitstack.py", line 20, in __call__n    raise en  File "/Library/Caches/pypoetry/virtualenvs/service-Qx3_L5c2-py3.12/lib/python3.12/site-packages/fastapi/middleware/asyncexitstack.py", line 17, in __call__n    await self.app(scope, receive, send)n  File "/Library/Caches/pypoetry/virtualenvs/service-Qx3_L5c2-py3.12/lib/python3.12/site-packages/starlette/routing.py", line 718, in __call__n    await route.handle(scope, receive, send)n  File "/Library/Caches/pypoetry/virtualenvs/service-Qx3_L5c2-py3.12/lib/python3.12/site-packages/starlette/routing.py", line 276, in handlen    await self.app(scope, receive, send)n  File "Library/Caches/pypoetry/virtualenvs/service-Qx3_L5c2-py3.12/lib/python3.12/site-packages/starlette/routing.py", line 66, in appn    response = await func(request)n               ^^^^^^^^^^^^^^^^^^^n  File "/Library/Caches/pypoetry/virtualenvs/service-Qx3_L5c2-py3.12/lib/python3.12/site-packages/fastapi/routing.py", line 273, in appn    raise RequestValidationError(_normalize_errors(errors), body=body)nfastapi.exceptions.RequestValidationError: [{'type': 'model_attributes_type', 'loc': ('body',), 'msg': 'Input should be a valid dictionary or object to extract fields from', 'input': None, 'url': 'https://errors.pydantic.dev/2.6/v/model_attributes_type'}]"}

model validated and request proceed rest of the logic