We Keep Coding

How to validate ObjectId query param in FastAPI

I have an endpoint that recibe and id field used to get data from MongoDB's _id:
from fastapi import APIRouter
from bson import ObjectId
router = APIRouter()
#router.get("/get-data")
async def get_strategies(order_id: ObjectId):
return Manager().get_data(order_id)
I want validate if order_id is valid as ObjectId, if later, inside the function, order_id is a str or ObjectId it doesn't matter.
How can I do this?
Thanks for help!

I found this validator: Query, this is used to validate http GET parameters.
Also there is this validator: Path to validate path parameters, below I left and example:
from fastapi import APIRouter, Path, Query
from bson import ObjectId
router = APIRouter()
#router.get("/get-data")
async def get_strategies(order_id: str = Query(..., regex=r"^[0-9a-f]{24}$")):
return Manager().get_data(order_id)
#router.get("/get-data/{order_id}")
async def get_strategies(order_id: str = Path(..., regex=r"^[0-9a-f]{24}$")):
return Manager().get_data(order_id)
The ... inside Query and Path is to indicate parameter is required.
ObjectId is an hexadecimal string with 24 characters. that is mached with the regex

issue creating an user with calculated field fastAPI

I have a simple API to insert data inside an object type dictionary, my issue is when I try to save a calculated field. Example code:
from fastapi import FastAPI
from pydantic import BaseModel
app = FastAPI()
users = {}
class User(BaseModel):
name: str
email: str
calculated: float
#app.post('/user-create/{id_user}')
def creating_an_user(id_user:int,user:User):
calculated = 1+2+3*2
if id_user in users:
return {"Error":"User ID already exists."}
users[id_user] = {
"name":user.name,
"email":user.email,
"calculated":user.calculated #should I need to put just like that ?
}
return users[id_user]
Obviously I receive an error, I think because my method is waiting a manually insert "calculated" field but is not:
TypeError: Failed to execute 'fetch' on 'Window': Request with GET/HEAD method cannot have body.
I am lost in this concern, can anybody help me on this?

Use FastAPI to parse incoming POST request from Slack

I'm building a FastAPI server to receive requests sent by slack slash command. Using the code below, I could see that the following:
token=BLAHBLAH&team_id=BLAHBLAH&team_domain=myteam&channel_id=BLAHBLAH&channel_name=testme&user_id=BLAH&user_name=myname&command=%2Fwhatever&text=test&api_app_id=BLAHBLAH&is_enterprise_install=false&response_url=https%3A%2F%2Fhooks.slack.com%2Fcommands%BLAHBLAH&trigger_id=BLAHBLAHBLAH
was printed, which is exactly the payload I saw in the official docs. I'm trying to use the payload information to do something, and I'm curious whether there's a great way of parsing this payload info. I can definitely parse this payload using split function or any other beautiful functions, but I'm curious whether there is a 'de facto' way of dealing with slack payload. Thanks in advance!
from fastapi import FastAPI, Request
app = FastAPI()
#app.post("/")
async def root(request: Request):
request_body = await request.body()
print(request_body)

Receive JSON data
You would normally use Pydantic models to declare a request body - if you were about to receive data in JSON form - thus benefiting from the validation that Pydantic has to offer (for more options on how to post JSON data, have a look at this answer). So, you would define a model like this:
from pydantic import BaseModel
class Item(BaseModel):
token: str
team_id: str
team_domain: str
# etc.
#app.post("/")
def root(item: Item):
print(item.dict()) # convert to dictionary (if required)
return item
The payload would look like this:
{
"token": "gIkuvaNzQIHg97ATvDxqgjtO"
"team_id": "Foo",
"team_domain": "bar",
# etc.
}
Receive Form data
If, however, you were about to receive the payload as Form data, just like what slack API does (as shown in the link you provided), you could use Form fileds. With Form fields, your payload will still be validated against those fields and the type you define them with. You would need, however, to define all the parameters in the endpoint, as described in the above link and as shown below:
from fastapi import Form
#app.post("/")
def root(token: str = Form(...), team_id: str = Form(...), team_domain: str = Form(...)):
return {"token": token, "team_id": team_id, "team_domain": team_domain}
or to avoid that, you may want to have a look at this post, which describes how to use Pydantic models with Form fields. As suggested in one of the answers, you can do that even without using Pydantic models, but instead with creating a custom dependency class using the #dataclass decorator, which allows you to define classes with less code. Example:
from dataclasses import dataclass
from fastapi import FastAPI, Form, Depends
#dataclass
class Item:
token: str = Form(...)
team_id: str = Form(...)
team_domain: str = Form(...)
#...
#app.post("/")
def root(data: Item = Depends()):
return data
As FastAPI is actually Starlette underneath, even if you still had to access the request body in the way you do in the question, you should rather use methods such as request.json() or request.form(), as described in Starlette documentation, which allow you to get the request body parsed as JSON or form-data, respectively.

How to partially update data with FastAPI and PyDantic BaseModel using PATCH

I'd like to partly update database via PATCH method in FastAPI. I use Postgres as my database, Postman to test.
I followed the example on FastAPI document, link: https://fastapi.tiangolo.com/tutorial/body-updates/#partial-updates-with-patch
I use GET to fetch the original data in DB, copy the content to body raw json, then change the part where I need to update and choose PATCH, click send in Postman, an error occurs: main.Product() argument after ** must be a mapping, not Product
What is the right approach to PATCH data? I omitted the code to connect to Postgres using psycopg2
from fastapi import FastAPI, Response, status, HTTPException, Path
from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel
app = FastAPI()
class Product(BaseModel):
name: str
price: float
inventory: int
#app.get("/posts/{id}")
def get_a_post(id: int = Path(None, title='Prod ID')):
cursor.execute('''SELECT * FROM public.products WHERE ID = %s''',(str(id),))
post = cursor.fetchone()
if not post:
raise HTTPException(status_code=status.HTTP_404_NOT_FOUND,
detail=f"product with id {id} was not found!")
return post
#app.patch("/posts/{id}", response_model=Product)
def patch_posts(id: int, post: Product):
stored_data = post
stored_model = Product(**stored_data)
update_data = post.dict(exclude_unset=True)
updated_data = stored_model.copy(update=update_data)
post = jsonable_encoder(updated_data)
return{"partially updated product": post}

Looks like your issue is caused by trying to get the key/value pairs via **stored_data, but that variable is of type Product.
In your patch_posts function, change stored_data = post to stored_data = post.dict().
Using the example you provided:
import uvicorn
from fastapi import FastAPI
from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel
app = FastAPI()
class Product(BaseModel):
name: str
price: float
inventory: int
#app.patch("/posts/{id}", response_model=Product)
def patch_posts(id: int, post: Product):
stored_data = post.dict()
stored_model = Product(**stored_data)
update_data = post.dict(exclude_unset=True)
updated_data = stored_model.copy(update=update_data)
post = jsonable_encoder(updated_data)
return post

Changing schema name in OpenAPI docs generated by FastAPI

I'm using FastAPI to create backend for my project. I have a method that allows to upload a file. I implemented it as follows:
from fastapi import APIRouter, UploadFile, File
from app.models.schemas.files import FileInResponse
router = APIRouter()
#router.post("", name="files:create-file", response_model=FileInResponse)
async def create(file: UploadFile = File(...)) -> FileInResponse:
pass
As you can see, I use a dedicated pydantic model for a method result—FileInResponse:
from pathlib import Path
from pydantic import BaseModel
class FileInResponse(BaseModel):
path: Path
And I follow this naming pattern for models (naming models as <Entity>InCreate, <Entity>InResponse, and so on) throughout the API. However, I couldn't create a pydantic model with a field of the type File, so I had to declare it directly in the route definition (i.e. without a model containing it). As a result, I have this long auto generated name Body_files_create_file_api_files_post in the OpenAPI docs:
Is there a way to change the schema name?

If you take a look at response model you see this:
It receives the same type you would declare for a Pydantic model atribute, so it can be a Pydantic model, but it can also be, e.g. a list of Pydantic models, like List[Item].
FastAPI will use this response_model to:
Convert the output data to its type declaration.
Validate the data.
Add a JSON Schema for the response, in the OpenAPI path operation.
Will be used by the automatic documentation systems.
That mean that response model is use to return json not a file like you want to do.
I couldn't create a pydantic model with a field of the type File
This is totaly normal
so I had to declare it directly in the route definition (i.e. without a model containing it)
And that's normal too, remember that File is not a python type nor a pydantic specific type so it can't be part of a model inheritating from pydantic BaseModel.
To do a file response you can follow the official doc:
from fastapi import FastAPI
from fastapi.responses import FileResponse
some_file_path = "large-video-file.mp4"
app = FastAPI()
#app.get("/")
async def main():
return FileResponse(some_file_path)
if you want to return a file like object (i.e. file from an instance of UploadFile) follow this part of the doc:
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
some_file_path = "large-video-file.mp4"
app = FastAPI()
#app.get("/")
def main():
def iterfile():
with open(some_file_path, mode="rb") as file_like:
yield from file_like
return StreamingResponse(iterfile(), media_type="video/mp4")