Python: FastAPI error 422 with post request

Python: FastAPI error 422 with post request

Straight from the documentation:

The function parameters will be recognized as follows:

• If the parameter is also declared in the path, it will be used as a path parameter.
• If the parameter is of a singular type (like int, float, str, bool, etc) it will be interpreted as a query parameter.
• If the parameter is declared to be of the type of a Pydantic model, it will be interpreted as a request body.

So to create a POST endpoint that receives a body with a user field you would do something like:

from fastapi import FastAPI
from pydantic import BaseModel


app = FastAPI()


class Data(BaseModel):
    user: str


@app.post(/)
def main(data: Data):
    return data

In my case, I was calling the python API from different python project like this

queryResponse = requests.post(URL, data= query)

I was using the data property, I changed it to json, then it worked for me

queryResponse = requests.post(URL, json = query)

Python: FastAPI error 422 with post request

For POST Requests for taking in the request body, you need to do as follows

Create a Pydantic Base Model User

from pydantic import BaseModel

class User(BaseModel):
    user_name: str


@app.post(/)
def main(user: User):
   return user