I have FastAPI function like this:
@router.post("/test/")
async def test(ids: List[str] = Body(..., )):
# some logic
I want "ids" field as required and pass there values like ["1", "2"]. If I pass a valid list it working fine. But if I pass empty list - [], this is also will be valid param and I dont want that. I can write function that checks it myself pretty easy, but I feel from my expirience with this wonderful framework that FastAPI have it covered already and I just dont know how.
from pydantic import BaseModel, validator
class MyModel(BaseModel):
ids: List[str] = []
@validator('ids', pre=True, always=True)
def validate_ids_length(cls, value):
if len(value) == 0:
raise ValueError("empty list not allowed")
return value
@demo_app.post("/test/")
async def test(data: MyModel = Body(...)):
return datamin_items argument of Field--(Pydantic Doc) classfrom pydantic import BaseModel, Field
class MyModel(BaseModel):
ids: List[str] = Field(..., min_items=1)
@demo_app.post("/test/")
async def test(data: MyModel = Body(...)):
return dataexample cURL request:
curl -X POST "http://0.0.0.0:8000/test/" -H "accept: application/json" -H "Content-Type: application/json" -d "{\"ids\":[\"string\"]}"I finally found a solution (after about half-hour of research) - in pydantic you may pass min_items to indicate minimum amount of items in passing list.
More on options here:
https://pydantic-docs.helpmanual.io/usage/schema/#field-customisation
So in the end, pydantic + FastAPI for my case will be like this:
@router.post("/test/")
async def test(ids: List[str] = Body(..., min_items=1)):
# some logic
In this case we gain functionality of pydantic, but without need of pydantic BaseModel class
I 'd prefer a validator since most endpoints won't be simple like this.
from pydantic import validator, BaseModel
from fastapi import FastAPI, Body
from typing import List
app = FastAPI()
class User(BaseModel):
ids: List[str]
@validator("ids", pre=True, always=True)
def check_ids(cls, ids):
assert len(ids) > 0, "ID's cannot be empty."
return ids
@app.post("/test")
async def get_ids(user: User = Body(...)):
return user
cls in this scenario?