Post JSON to FastAPI

How to pass JSON to POST request in FastAPI ?

You can pass paramters to the FastAPI POST endpoint using pydantic. But to use pydantic you need to pre define the JSON structure. What if you don’t know the structure?

You can access the passed request body using request. Start by importing request from FastAPI.

from fastapi import Request

Declare the type of the parameter as Request. When passing pre defined JSON structure or model to POST request we had set the parameter type as the pre defined model.

from fastapi import FastAPI, Request
my_app = FastAPI()

@my_app.post("/getInformation")
async def getInformation(info : Request):
    req_info = await info.json()
    return {
        "status" : "SUCCESS",
        "data" : req_info
    }

As seen in the above code, you need to await the info.json() to read the JSON data. Save the changes and hit a POST request to the http://localhost:8000/getInformation and you will get the passed in request in the data key of the response.

I tried posting the following JSON,

{
	"id" : 100,
	"name" : "Jay",
    "city" : "Kochi"
}

Here is the response JSON from the POST endpoint.

{
    "status": "SUCCESS",
    "data": {
        "id": 100,
        "name": "Jay",
        "city":"Kochi"
    }
}