Fastapi depends not working. We create an async function lifespan () with yield like this: from contextlib import asynccontextmanager from fastapi But whenever you need them and go and learn them, know that you can already use them directly in FastAPI. responses import StreamingResponse app = fastapi. Rewrite it using router. Any request with an Origin header. . Aug 13, 2021 · Here is many solutions and it depends on what you want to do: Why does FastAPI's Depends() work without any parameter passed to it? 4. Since fastapi-router-controller is not a parting of the fastapi-utils CBV class, I didn't thought at this feature when I implemented it. Mar 3, 2021 · I am currently working on a POC using FastAPI on a complex system. Let's imagine that you have your backend API in some domain. sleep) def print_event(sc): May 23, 2021 · Thanks again @MatsLindh, understand what you mean, but Dependenices generally as the Depends class in Fastapi exists for completely different reasons, not to initialize heavy services, but to make your modules more abstrat dependents. 8+ non-Annotated. any_param = any_param. My API looks as follows. that is why the caching is not working properly. To create a Pydantic model and use it to define query parameters, you would need to use Depends () along with the parameter in your endpoint. I use fastapi_cache module and Redis like this: from fastapi import Depends, FastAPI, Query, Nov 21, 2021 · While the answer above about writing a middleware does work, if you don't want a middleware, you just want to use the include_router, then you can take the authenticate_and_decode_JWT method and extend it to write the JWT payload into the request object and then later have your routes read from that out from the request object. 3 – FastAPI Dependency Injection using Classes. inferring_router import InferringRouter def get_x(): return 10 app = FastAPI() router = InferringRouter() # Step 1: Create a router @cbv(router) # Step 2: Create and decorate a class to hold the endpoints class Foo: # Step 3: Add dependencies as class Oct 11, 2023 · return response. Connect and share knowledge within a single location that is structured and easy to search. The second issue is about working with swagger. Starlette (and FastAPI) are based on AnyIO, which makes it compatible with both Python's standard library asyncio and Trio. route directly. Apr 14, 2021 · 8. And to create fluffy, you are "calling" Cat. I'm running a FastAPI app in Python using uvicorn on a Windows machine without a frontend (e. If you want to execute it in a thread, then you can use the FastAPI tools: import asyncio. FastAPI doesn't require you to use a SQL (relational) database. Jan 20, 2022 · 127. get and it should work. The path operation decorator receives an optional argument dependencies. If the query parameters are known when starting the API but you still wish to have them dynamically set: from fastapi import FastAPI, Depends. 5 – Add Dependencies to FastAPI Path Operation Decorators. app = FastAPI() # Put your query arguments in this dict. Next. scheduler(time. on_event. Function that is used to validate the token in the case that it requires it. So in a normal endpoint you might define a path parameter like so: return {"item_id": item_id} Now if you want to use that parameter in a dependency, you can simply do: return {"item_id": item_id} return my_dependency. Now that we have all the security flow, let's make the application actually secure, using JWT tokens and secure password hashing. from fastapi import FastAPI. 61. finally: db. The original dependency could be used in a path operation function, a path operation decorator (when you don't use the return value), a . add adds that ORM object to the session (i. In reality it is dependencies=[Depends(permission_required(resource, Operation. 0, the parameter was called regex instead of pattern, but it's now deprecated. Here is a minimal example: import os import time import fastapi from fastapi import Depends, HTTPException, status, Request from fastapi. 6+ based on standard Python type hints. And it will save the returned value in a "cache" and pass it to all the "dependants Apr 27, 2023 · Stack Overflow Public questions & answers; Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Talent Build your employer brand Apr 22, 2020 · Alternatively, you can try removing the "async" from def background_task. Jun 9, 2020 · 14. """. The fake database gets created but still, the real one is being used by the tests (which is a huge problem). " To best understand it, let’s look at an example: Oct 5, 2020 · It does not necessarily have to be best or simplest approach. db = SessionLocal() try: yield db. I just mentioned what limits FastAPI Depends has, to emphasize that it doesn't fixes my problem. The key point is that i want to use a python Enum and i want to be able to use the Enum's names in the additional data (query parameters). Nevertheless thanks for your suggestion anyway. Having dropped all dependencies in one test, you will not pass the subsequent ones that use common dependencies. I am using dependencies to get database session. Session is yielded value. , to query parameters, you could wrap the Query () in a Field (). Aug 18, 2023 · I have a simple crud app. 100. Problem is with the response /logout endpoint is returning. 4 – Handling Sub-dependencies. FastAPI has an elegant and simple dependency injection system. One of the key advantages of FastAPI is its built-in support for handling user authentication and authorization. Dec 9, 2021 · from fastapi import FastAPI, Body, Depends from starlette. That is the underlying method in Starlette, meaning you bypass all FastAPI specific functionality, like Depends. 8+ Python 3. It takes each request that comes to your application. Dec 4, 2021 · Dependency injection (DI) is a way for your code functions and/or classes to declare things they need to work. Learn more about Teams Jun 17, 2021 · Sorted by: 9. get the other in @app. 7 COPY . @router. Using the same dependency multiple times. 1:37772 - "POST /event/22 HTTP/1. Nov 13, 2023 · From FastApi doc : To override a dependency for testing, you put as a key the original dependency (a function), and as the value, your dependency override (another function). . Oct 22, 2022 · FastAPI does quite a bit of magic to make it work with the request cycle, (I'm halfway guessing this part, but I think this is fairly accurate) and since any method that has their dependencies evaluated is wrapped in another function (i. FastAPI will make sure that the "exit code" in each dependency with yield is run in the correct order. I follow the advice and add a status Classes as dependencies. dependency_overrides["get_msg"] = get_new_msg() You are passing the dependency as string instead of the actual dependency. Aug 11, 2022 · I searched the FastAPI documentation, with the integrated search. 0 Bigger Applications - Multiple Files. def __str__(self): Sep 25, 2020 · In your case, you passing a form data to your endpoint. It's not documented, but you can make non- pydantic classes work with fastapi. If you try interacting with any of the two user interfaces, they will work correctly, because the browser will be able to talk to each specific app or sub-app. 6 – FastAPI Global Dependencies. js, etc. The app is functioning fully it is just the connection to the FastAPI default docs page that doesn't work. Plus the answer(s) to that question would not have solved my issue/question. Dec 15, 2023 · I am creating a fastapi authentication system (register and login) and following documentation. and the caching is being done by fastapi dependency. Dec 9, 2020 · When testing, make sure you add Origin header to your request. These dependencies will be executed/solved the same way as normal dependencies. I used the GitHub search to find a similar issue and didn't find it. Technical Details: root_path ¶ When you mount a sub-application as described above, FastAPI will take care of communicating the mount path for the sub-application using a mechanism from May 10, 2022 · The subscribe. A "middleware" is a function that works with every request before it is processed by any specific path operation. Depends needs a function to call (it expects a callable as you can see in the error). Here is the code to init fastapi-cache @asynccontextmanager async def lifespan(app: FastAPI): redis = aioredis. For example, dependency_c can have a dependency on dependency_b, and dependency_b on dependency_a: Python 3. Learn more about Teams Jan 22, 2021 · Based on this, we can conclude that the author of the framework does not see any danger in this. from fastapi import Form, Depends. routes list. from typing import Annotated from fastapi import Depends async def dependency_a(): dep_a Add dependencies to the path operation decorator. If you need to authenticate certain paths just with JWT, you can use directly that dependency (the same approach applies for only KEY authentication) – lsabi. As @JarroVGIT said, we can use connection pooling to maintain the connection from FastAPI to Redis and reduce open-closing connection costs. 1 – What is Dependency Injection? Dependency Injection is a programming approach. Oct 25, 2019 · edited. But their value (if they return any) won't be passed to your path operation function. from threading import Thread. app = FastAPI() Oct 23, 2020 · 5. I have tried several ways to implement it Feb 26, 2020 · The app for the server is server and the nginx app is a different one, at least that's the way all the examples I've seen work. The read_item route uses the get_db_connection dependency to get a database connection from the pool and use it within the route. To do that, we declare a method __call__: Python 3. In particular, you can directly use AnyIO for your advanced concurrency use cases that require more advanced patterns in your own code. Depends function is part of the FastAPI dependency injection system. a session where different ORM objects are tracked and referenced from start to finish. Feb 4, 2022 · I added a very descriptive title to this issue. Feb 1, 2022 · なんとか生きてる ︎. If that's what you want, it was supported from the beginning, and it's in the docs. It can be an async def or normal def function, FastAPI will know how to handle it correctly. While first tests runs through the other test fails: So, FastAPI will take care of filtering out all the data that is not declared in the output model (using Pydantic). You add something like user: User = Depends (auth_function) to the path or function. This project is heavy in business logic and will interact with 50+ different database tables when completed. I already checked if it is not related to FastAPI but to Pydantic. The issue is with this: app. Mar 12, 2023 · Could someone tell me how I can test an endpoint that uses the new lifespan feature from FastAPI? I am trying to set up tests for my endpoints that use resources from the lifespan function, but the test failed since the dict I set up in the lifespan function is not passed to the TestClient as part of the FastAPI app. I'm trying to run pytest in my fastapi app but even if I follow the tutorial line by line it doesn't work. optional_oauth2_scheme = OAuth2PasswordBearer(tokenUrl="auth", auto_error=False) async def get_user_or_none(db: Session = Depends(get_db), token: str | None = Depends(optional_oauth2_scheme)): Dec 10, 2020 · As an example: The dependency class (just the initialization, which captures the dependency parameters): class DatalakeConnection(object): """Using FastAPI's `Depends` Dependency Injection, this class can have all. Mar 30, 2021 · I also read the fastapi-utils documentation and understood what is your expected behavior. You could instead use a repeating Event scheduler for the background task, as below: import sched, time. response_model or Return Type¶. The new docs will include Pydantic v2 and will use SQLModel (which is also based on SQLAlchemy) once it is updated to use Pydantic v2 as well. health from app. works perfectly from command line with Fastapi 0. May 17, 2021 · Still, I have tried all the solutions there are on the internet and could not make it work. query_params = {"name": (str, "me")} query_model = create_model("Query", **query_params) # This is subclass Lifespan. def __init__(. Conclusion. To add description, title, etc. I would like to authenticate with swagger of fastapi. Each model has a service, and some of the more complex business logic has its own service (which then interacts/queries with the different tables through the model May 18, 2020 · FastAPI provides a way to manage dependencies, like DB connection, via its own dependency resolution mechanism. from_url("r Jul 5, 2023 · For my tests I want to use a test database and for that I use dependency overriding. In this case, because the two models are different, if we annotated the function return type as UserOut, the editor and tools would complain that we are returning an invalid type, as those are different classes. Jan 5, 2024 · 3. self. The snippet below contains two dependency_overrides statements, one in a @app. Info. And you have a frontend in another domain or in a different path of the same domain (or in a mobile application). If one of your dependencies is declared multiple times for the same path operation, for example, multiple dependencies have a common sub-dependency, FastAPI will know to call that sub-dependency only once per request. add_api_route. Its documented use-case is in a signature of a FastAPI "endpoint" function, i. This adds the route of the default type APIRoute (with the path, the path operation function, and other elements such as dependencies, response codes etc. include_router () call, etc. But user Vlad is right. Middleware. Describe the bug The request remains open/active until the background task finishes running, making the purpose of BackgroundTasks kind of useless. 4. it needs to get a token directly. Apr 13, 2023 · 13. FastAPI will still be able to override it. that you want it tracked in the database), while commit actually writes the changes to the database. I am using sqlalchemy, postgres and pydantic models. ) so there should NOT be any iteraction between a local frontend and backend like there is in this question. name = name app = FastAPI() @app. Ideally, I'd be able to just call fastapi. Changing to a BackgroundTask for running the logs made it work! Solution: @app. However, my endpoints are also accessing the production database. Jan 27, 2022 · Option 2. It can then do something to that request or run any needed code. from typing import Annotated from fastapi import Depends, FastAPI app = FastAPI() class Mar 2, 2023 · There's not really a difference in what those two do, so either would work just fine - not sure what the problem would be with either case (you can also create a base APIRouter and register the other routers under that one, to avoid having to give a prefix to each router when you include it). Feb 13, 2023 · The reason Depends is not working is, as @MatsLindh is asking about, that you are calling router. FastAPI has built-in support for handling authentication through the use of JSON Web Tokens (JWT). security = HTTPBearer() async def has_access(credentials: HTTPAuthorizationCredentials= Depends(security)): """. get , etc. A simple solution could be to have a unique Dependency that performs the check and calls the correct authentication method (JWT or KEY). Pydantic v1 regex instead of pattern¶ Before Pydantic version 2 and before FastAPI 0. If this was the problem it wouldn't have worked at all. Depends ( get_value ) return decorator. any_other_param = any_other_param. # execute finally on exit from with. The FastAPI dependency injection doesn't work in functions without that decorator. 9+ Python 3. testclient import TestClient. class AnyForm: def __init__(self, any_param: str = Form(), any_other_param: int = Form(1)): self. And as I've stated it's on a local cluster. """. delete_cookies (key="access_token") is able to delete the cookie successfully. But when you the url address bar does not change to the new one and stay the same as before. g. I found a solution for this issue and will post the answer down here. Write your own async code. Oct 22, 2019 · Not sure if you meant because in the route dependency I have permission_required(), but I just omitted the function parameters in this example, sorry if that caused confusion. fixture() def client(): with TestClient(app) as test_client: yield test_client def test_simple(client Sep 8, 2020 · Setting Cookie values currently does not work via SwaggerUI due to browser security restrictions. Which is working locally with uvicorn main:app, but not when I build using this Dockerfile: FROM tiangolo/uvicorn-gunicorn-fastapi:python3. And also with every response before returning it. It is just a standard function that can receive parameters. What is dependency injection? Dependency injection is a fancy way of saying "functions/objects should have the variables they depend on passed into them, instead of constructing it themselves. import uvicorn. I have some dependencies I want to inject, like some logging and data access classes, for testing purposes (being able to mock them out for unit testing). FastAPI Learn Tutorial - User Guide Security Security - First Steps¶. Tip. Jan 21, 2024 · The answer of yurii-motov is correct but can be slightly improved. The recommended style with FastAPI seems to be to use Dependencies. Anyway, If this could your work, I'll implement it as a new feature in a future version. And your FastAPI application with WebSockets will respond back: You can send (and receive) many messages: And all of them will use the same WebSocket connection. You might notice that to create an instance of a Python class, you use that same syntax. – Nov 14, 2022 · Yes, the dependency should be resolved as expecting int as the input parameter; the signature in the view function itself is what the function can expect the type of x to be in that function. It should also be noted that one could use the Literal type instead of Enum, as described here and here. e. exception_handler Jul 27, 2023 · the reason is that each time I am passing a value to the Dep class it is creating a new object and the call method is that of a new object each time. Feb 25, 2022 · This is covered in the FastAPI reference manual, albeit just as a small note: async def read_items(q: Optional[str] = None): FastAPI will know that the value of q is not required because of the default value = None. pass. close() return SomeService(db) Now in my tests I'd like to test SomeService but without making any requests to the app. FastAPI() def ask_statesman(query: str): completion_reason = None while not completion_reason or completion_reason == "length": for line in range(10): completion_reason = f"hello{line Jun 12, 2023 · To implement authentication for a FastAPI endpoint, I want to make use of the Depends functionality offered in the latest versions (>=0. You need to use a different OAuth2PasswordBearer for these optionally authenticated endpoints with auto_error=False, e. Not the class itself (which is already a callable), but an instance of that class. Answering your second question, I would not advice for such complex dependencies. return value return fastapi. Jul 20, 2020 · from fastapi. Seems to work as expected. My code is: Jun 6, 2021 · 3. The Optional in Optional [str] is not used by FastAPI, but will allow your editor to give you better support and detect errors. /app /app RUN pip install -r requirements. |auth \\ . 需要ないかもだけど、そもそも依存性なんぞな人間が、FastAPIでDependsと関数呼び出しとかで混乱したので(理解とかじゃなく、実装時にあれれってなった感じ)メモ. credentials. Depends (get_database, singleton=True) (or something like that). one decorated with @app. Feb 18, 2021 · 20. For now, I think we'll have to fall back to the deprecated lifecycle events pattern or something like this: Aug 8, 2022 · Fastapi - run a function with dependencies outside of request. cbv import cbv from fastapi_utils. from starlette. main import app # this is my application (FastAPI instance) with the `router` attached @pytest. You could still see some code using it: Nov 29, 2020 · Being very new to FastAPI I am strugling to test slightly more difficult code than I saw in the tutorial. Feb 8, 2020 · If you're only looking at abstracting the form data into a class you can do it with a plain class. Share. If you are building an application or a web API, it's rarely the case that you can put everything on a single file. background = BackgroundTask(write_log_data, request, response) return response. 95) of FastAPI. ) to the Fastapi. You may have a dependency common to several tests and a dependency used only in one test. In a nutshell, you declare what you need in a function signature, and FastAPI will call the functions(or classes) you mentioned and inject the correct results when the handler is called. Nov 7, 2020 · 633 12 27. I already read and followed all the tutorial in the docs and didn't find an answer. It will try to jsonify them using vars (), so only straight forward data containers will work - no using property, __slots__ or stuff like that [1]. txt and start with Feb 3, 2023 · FastAPI is a modern, fast (high-performance), web framework for building APIs with Python 3. Something like this would work: from fastapi import FastAPI. That gets called before your endpoint function, similar to how a decorator wraps it. import greetings_service. 1" 405 Method Not Allowed OK, I see that for some reason a POST request is called instead of a GET request. That is why when I call an endpoint for the next times, I do not see new logs Sep 11, 2020 · from fastapi import Depends, FastAPI from fastapi_utils. from contextlib import contextmanager. decorated with a route), this function is what resolves the dependencies for a given situation (and can May 30, 2023 · Teams. testclient import TestClient import app. security import HTTPAuthorizationCredentials, HTTPBearer. Mar 2, 2021 · I am facing an issue with FastAPI and Depends. responses import HTMLResponse from app. Feb 21, 2022 · 1 – What is Dependency Injection? 2 – Intro to FastAPI Dependency Injection. Aug 5, 2021 · A FastAPI dependency function can take any of the arguments that a normal endpoint function can take. When you yield something else it doesn't know what to do with that - since you're now calling the function instead of giving it to Depends. model import PostSchema, UserSchema, UserLoginSchema from app. listen() is also not async. I searched the FastAPI documentation, with the integrated search. responses import JSONResponse class UnicornException(Exception): def __init__(self, name: str): self. Q&A for work. from pydantic import create_model. Looking at the documentation it seemed like using the Depends functionality on the router methods would do what I needed it to do. You can set a dependency override for a dependency used anywhere in your FastAPI application. Create a task function¶ Create a function to be run as the background task. But keep in mind that the code will execute synchronously. time, time. I have two functions that my code Depends on, also the second one depends on the first. Here we'll see an example using SQLAlchemy. And you want to handle this exception globally with FastAPI. name = name fluffy = Cat(name="Mr Fluffy") In this case, fluffy is an instance of the class Cat. Oct 27, 2020 · from fastapi import Depends from handler import ServiceHandler async def get_service_handler(handler=Depends(ServiceHandler)): return handler then the test will Jun 12, 2023 · The FastAPI docs do mention that this is not supported for sub-applications, but perhaps that should be updated to include sub-routers, too. app = FastAPI() s = sched. Using Depends and others¶ In WebSocket endpoints you can import from fastapi and use: Depends; Security; Cookie; Header; Path; Query; They work the same way as for other FastAPI Mar 1, 2024 · My custom field_validator is working when using the model class directly but it is not working as expected, when using it via FastAPI and Depends(). middleware("http") async def custom_middleware_logging(request: Request, call_next): response = await call_next(request) response. The avoid the need of duplicating the getter function I replaced @alru_cache with a small decorator of my own that does the same for my case and returns an async function which is automatically awaited by the dependency injection system of fastAPI as desired. My Structure Code: src \\ . READ))], I assume it not to be relevant here, but will edit it above. get ("/status", response_model=Status) Sep 7, 2022 · it is a good practice to redirect user to the next endpoint after login and get access token. In that case the task should run in a thread pool instead which would then also not block. FastAPI will create the object of type BackgroundTasks for you and pass it as that parameter. For this reason i am using a custom validator to only Sep 1, 2022 · Depends will evaluate every time your function got a request, so your second example will create a new connection for each request. In this case the middleware will pass the request through as normal, but will include In Python there's a way to make an instance of a class a "callable". exception_handler (): from fastapi import FastAPI, Request from fastapi. Let's start with an example and then see it in detail. Sep 4, 2019 · What I'm understanding from the original issue is that the idea is to be able to instantiate an object of some class, passing the parameters needed for class creation, and then use that singleton parameterized object as a dependency. For example: class Cat: def __init__(self, name: str): self. token = credentials. And then FastAPI will call that override instead of the original dependency. If you want to get more technical: Dependency injection relies on composition, and is a method for achieving inversion of control. You can define this startup and shutdown logic using the lifespan parameter of the FastAPI app, and a "context manager" (I'll show you what that is in a second). 2022年1月31日 17:06. It resembles a pytest fixture system. May 26, 2022 · In 'normal' routes (like your /get route), the route is added to the Fastapi application with the Fastapi. Feb 22, 2021 · This might be slightly bike shedding, but if there's a quick fix to work around this limitation in any way I'd be interested to find a way to both achieve validation (either through Depends() or in some alternative way without doing it explicitly in each API route function that requires that functionality) and a flat JSON layout that matches my . Otherwise CORSMiddleware will not send back the cors headers. But you can use any relational database that you want. To process it, you need to install python-multipart via pip and rewrite your function a little: May 11, 2021 · Teams. What you need to do is: Tell pydantic that using arbitrary classes is fine. – Aug 11, 2022 · I searched the FastAPI documentation, with the integrated search. On creating TemplateResponse object while returning, it creates a new response copying the same cookies from the request and kind of shadow the change (delete cookies FastAPI Learn Tutorial - User Guide Security OAuth2 with Password (and hashing), Bearer with JWT tokens¶. At least for the time being. You can add middleware to FastAPI applications. I search for an explanation and find that the RedirectResponse object defaults to code 307 and calls POST link. You could add a custom exception handler with @app. import pytest from unittest import mock from fastapi import HTTPException from starlette. Mar 10, 2021 · with contextmanager(get_db)() as session: # execute until yield. So your get_db function needs to return a function that yields the database, where the string has Nov 17, 2022 · session here refers to the database session - i. As shown below, the line response. If the dependencies are at the router level, you can simply add them to the router, using the parameter depends=[] and providing a list of dependency classes/functions. Which I understand as : this is meant to override a function, not a class. Aug 30, 2021 · The fastapi. It should also have access to the req-resp context. The startup_event and shutdown_event functions use FastAPI's on_event system to create and close the database connection pool, respectively. FastAPI provides a convenience tool to structure your application while keeping all the flexibility. auth Oct 4, 2022 · Oct 4, 2022 at 20:17. 0. api. It may not be clear at first, but it is written here in the documentation: Simple requests. This is basically the same as what @sm-Fifteen suggests in issue 726, but neatly wrapped in a function. Jun 6, 2022 · In this post we'll go over what it is and how to effectively use it, with FastAPI ’s depends. I already searched in Google "How to X in FastAPI" and didn't find any information. elements needed to connect to a data lake. tj zm vz hu si sm wg ur gf ed