Let's say you want to POST JSON to one of your FastAPI endpoints and return some response. In this example, curl is used to post JSON to the FastAPI endpoint.

curl \
--request POST \
--url fastapi.example.com/api/v1 \
--header 'content-type: application/json' \
--data '{ "foo": "bar" }'

Here is the boilterplate code to handle the request and provide a response.

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()

class variables(BaseModel):
    foo: str
    bar: str

@app.post("/api/vi")
async def api_v1(item: variables):

  return item

In this example, FastAPI would simply return the JSON that was submitted in the POST request.

~]$ curl --request POST --url fastapi.example.com/api/v1 --header 'content-type: application/json' --data '{ "foo": "Hello", "bar": "World" }'
{"foo":"Hello","bar":"World"}

But what if we only post foo and not bar?

~]$ curl --request POST --url fastapi.example.com/api/v1 --header 'content-type: application/json' --data '{ "foo": "Hello" }' | jq
{
  "detail": [
    {
      "type": "missing",
      "loc": [
        "body",
        "bar"
      ],
      "msg": "Field required",
      "input": {
        "foo": "Hello"
      }
    }
  ]
}

"missing" was returned and makes for a bit of messy output. You can give default values

• None for str (strings)
• True or False for bool (booleans)

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()

class variables(BaseModel):
    foo: str = None
    bar: str = None
    validate: bool = False

@app.post("/api/vi")
async def api_v1(item: variables):

  return item

Often, you are going to want to do something with the value of the JSON.

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()

class variables(BaseModel):
    queue_name: str

@app.post("/api/vi")
async def api_v1(item: variables):

  return item.foo, item.bar