Fast API Request Body

Info

Sending data to server/client, the data is sent in the request body.

• API almost has to send response body.
• Client don't have to send often request body.

Datamodel Creation

Note

Datamodels are created with pydantic library.

Same logic with optional, default, required parameters.

Backend gets POST requestResult

from fastapi import FastAPI
from pydantic import BaseModel

class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None

app = FastAPI()

@app.post("/items/")
async def create_item(item: Item):
    return item

Response

{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
},
{
    "name": "Foo",
    "price": 45.2
}

Data Model Usage

Tip

Item Datamodel dict can be updated with new key-value pairs.

class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None

app = FastAPI()

@app.post("/items/")
async def create_item(item: Item):
    item_dict = item.dict()
    if item.tax:
        price_with_tax = item.price + item.tax
        item_dict.update({"price_with_tax": price_with_tax})
    return item_dict

Request Body & Path & Query Parameters

Info

FasAPI detects/defines all parameters name, also in Datamodels.

class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None

app = FastAPI()

@app.put("/items/{item_id}")
async def create_item(item_id: int, item: Item, q: str | None = None):
    result = {"item_id": item_id, **item.dict()}
    if q:
        result.update({"q": q})
    return result

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