Fastapi: [QUESTION] Undefined fields

Created on 19 Jan 2020 · 3Comments · Source: tiangolo/fastapi

First check

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Description

Hello. I have BaseModel from pydantic with some fields. From postman I pass another field. My application ignore them. But I want to my application trow exception for this case. How I do this type validation?

question

Source

Hedgehogues

Most helpful comment

@Hedgehogues
Hi! What you are looking for is an extra setting in the pydantic model config.

This works as follows:

from fastapi import FastAPI
from pydantic import BaseModel, BaseConfig

app = FastAPI()


class MyModel(BaseModel):
    field1: str
    field2: int

    class Config(BaseConfig):
        extra = "forbid"


@app.post("/my-route")
async def my_route(model_info: MyModel) -> None:
    # do something
    print(model_info.dict())

Using the httpie client and sending a request to this application, you'll get the following response:

$ http -v POST :8000/my-route field1=fastapi field2=42 field3=extra   
POST /my-route HTTP/1.1
Accept: application/json, */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Content-Length: 56
Content-Type: application/json
Host: localhost:8000
User-Agent: HTTPie/1.0.3

{
    "field1": "fastapi",
    "field2": "42",
    "field3": "extra"
}

HTTP/1.1 422 Unprocessable Entity
content-length: 113
content-type: application/json
date: Sun, 19 Jan 2020 11:55:56 GMT
server: uvicorn

{
    "detail": [
        {
            "loc": [
                "body",
                "model_info",
                "field3"
            ],
            "msg": "extra fields not permitted",
            "type": "value_error.extra"
        }
    ]
}

nsidnev on 19 Jan 2020

👍3

All 3 comments

@Hedgehogues
Hi! What you are looking for is an extra setting in the pydantic model config.

This works as follows:

from fastapi import FastAPI
from pydantic import BaseModel, BaseConfig

app = FastAPI()


class MyModel(BaseModel):
    field1: str
    field2: int

    class Config(BaseConfig):
        extra = "forbid"


@app.post("/my-route")
async def my_route(model_info: MyModel) -> None:
    # do something
    print(model_info.dict())

Using the httpie client and sending a request to this application, you'll get the following response:

$ http -v POST :8000/my-route field1=fastapi field2=42 field3=extra   
POST /my-route HTTP/1.1
Accept: application/json, */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Content-Length: 56
Content-Type: application/json
Host: localhost:8000
User-Agent: HTTPie/1.0.3

{
    "field1": "fastapi",
    "field2": "42",
    "field3": "extra"
}

HTTP/1.1 422 Unprocessable Entity
content-length: 113
content-type: application/json
date: Sun, 19 Jan 2020 11:55:56 GMT
server: uvicorn

{
    "detail": [
        {
            "loc": [
                "body",
                "model_info",
                "field3"
            ],
            "msg": "extra fields not permitted",
            "type": "value_error.extra"
        }
    ]
}

nsidnev on 19 Jan 2020

👍3

Yep. All what @nsidnev said :point_up:

Does that solve your issue @Hedgehogues ? If so, you can close it.