✨ Add parameter dependencies to path operation decorators and include_router (#235)

* ✨ Implement dependencies in decorator and .include_router

* 📝 Add docs for parameter dependencies

* ✅ Add tests for dependencies parameter

* 🔥 Remove debugging prints in tests

* 📝 Update release notes

docs/release-notes.md

@@ -1,5 +1,17 @@
 ## Next release
 
+* Add support for `dependencies` parameter:
+    * A parameter in *path operation decorators*, for dependencies that should be executed but the return value is not important or not used in the *path operation function*.
+    * A parameter in the `.include_router()` method of FastAPI applications and routers, to include dependencies that should be executed in each *path operation* in a router.
+        * This is useful, for example, to require authentication or permissions in specific group of *path operations*.
+        * Different `dependencies` can be applied to different routers.
+    * These `dependencies` are run before the normal parameter dependencies. And normal dependencies are run too. They can be combined.
+    * Dependencies declared in a router are executed first, then the ones defined in *path operation decorators*, and then the ones declared in normal parameters. They are all combined and executed.
+    * All this also supports using `Security` with `scopes` in those `dependencies` parameters, for more advanced OAuth 2.0 security scenarios with scopes.
+    * New documentation about [dependencies in *path operation decorators*](https://fastapi.tiangolo.com/tutorial/dependencies/dependencies-in-path-operation-decorators/).
+    * New documentation about [dependencies in the `include_router()` method](https://fastapi.tiangolo.com/tutorial/bigger-applications/#include-an-apirouter-with-a-prefix-tags-responses-and-dependencies).
+    * PR [#235](https://github.com/tiangolo/fastapi/pull/235).
+
 * Fix OpenAPI documentation of Starlette URL convertors. Specially useful when using `path` convertors, to take a whole path as a parameter, like `/some/url/{p:path}`. PR [#234](https://github.com/tiangolo/fastapi/pull/234) by [@euri10](https://github.com/euri10).
 
 * Make default parameter utilities exported from `fastapi` be functions instead of classes (the new functions return instances of those classes). To be able to override the return types and fix `mypy` errors in FastAPI's users' code. Applies to `Path`, `Query`, `Header`, `Cookie`, `Body`, `Form`, `File`, `Depends`, and `Security`. PR [#226](https://github.com/tiangolo/fastapi/pull/226) and PR [#231](https://github.com/tiangolo/fastapi/pull/231).

docs/src/bigger_applications/app/main.py

@@ -1,13 +1,20 @@
-from fastapi import FastAPI
+from fastapi import Depends, FastAPI, Header, HTTPException
 
 from .routers import items, users
 
 app = FastAPI()
 
+
+async def get_token_header(x_token: str = Header(...)):
+    if x_token != "fake-super-secret-token":
+        raise HTTPException(status_code=400, detail="X-Token header invalid")
+
+
 app.include_router(users.router)
 app.include_router(
     items.router,
     prefix="/items",
     tags=["items"],
+    dependencies=[Depends(get_token_header)],
     responses={404: {"description": "Not found"}},
 )

docs/src/dependencies/tutorial006.py

@@ -1,21 +1,19 @@
-from fastapi import Depends, FastAPI
+from fastapi import Depends, FastAPI, Header, HTTPException
 
 app = FastAPI()
 
 
-class FixedContentQueryChecker:
-    def __init__(self, fixed_content: str):
-        self.fixed_content = fixed_content
-
-    def __call__(self, q: str = ""):
-        if q:
-            return self.fixed_content in q
-        return False
+async def verify_token(x_token: str = Header(...)):
+    if x_token != "fake-super-secret-token":
+        raise HTTPException(status_code=400, detail="X-Token header invalid")
 
 
-checker = FixedContentQueryChecker("bar")
+async def verify_key(x_key: str = Header(...)):
+    if x_key != "fake-super-secret-key":
+        raise HTTPException(status_code=400, detail="X-Key header invalid")
+    return x_key
 
 
-@app.get("/query-checker/")
-async def read_query_check(fixed_content_included: bool = Depends(checker)):
-    return {"fixed_content_in_query": fixed_content_included}
+@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
+async def read_items():
+    return [{"item": "Foo"}, {"item": "Bar"}]

docs/src/dependencies/tutorial007.py

@@ -0,0 +1,21 @@
+from fastapi import Depends, FastAPI
+
+app = FastAPI()
+
+
+class FixedContentQueryChecker:
+    def __init__(self, fixed_content: str):
+        self.fixed_content = fixed_content
+
+    def __call__(self, q: str = ""):
+        if q:
+            return self.fixed_content in q
+        return False
+
+
+checker = FixedContentQueryChecker("bar")
+
+
+@app.get("/query-checker/")
+async def read_query_check(fixed_content_included: bool = Depends(checker)):
+    return {"fixed_content_in_query": fixed_content_included}

docs/tutorial/bigger-applications.md

@@ -22,16 +22,15 @@ Let's say you have a file structure like this:
 
 !!! tip
     There are two `__init__.py` files: one in each directory or subdirectory.
-    
+
     This is what allows importing code from one file into another.
 
     For example, in `app/main.py` you could have a line like:
-    
+
     ```
     from app.routers import items
     ```
 
-
 * The `app` directory contains everything.
 * This `app` directory has an empty file `app/__init__.py`.
     * So, the `app` directory is a "Python package" (a collection of "Python modules").
@@ -107,7 +106,7 @@ And we don't want to have to explicitly type `/items/` and `tags=["items"]` in e
 {!./src/bigger_applications/app/routers/items.py!}
 ```
 
-### Add some custom `tags` and `responses`
+### Add some custom `tags`, `responses`, and `dependencies`
 
 We are not adding the prefix `/items/` nor the `tags=["items"]` to add them later.
 
@@ -197,12 +196,11 @@ So, to be able to use both of them in the same file, we import the submodules di
 {!./src/bigger_applications/app/main.py!}
 ```
 
-
 ### Include an `APIRouter`
 
 Now, let's include the `router` from the submodule `users`:
 
-```Python hl_lines="7"
+```Python hl_lines="13"
 {!./src/bigger_applications/app/main.py!}
 ```
 
@@ -221,13 +219,12 @@ It will include all the routes from that router as part of it.
 
 !!! check
     You don't have to worry about performance when including routers.
-    
+
     This will take microseconds and will only happen at startup.
-    
+
     So it won't affect performance.
 
-
-### Include an `APIRouter` with a `prefix`, `tags`, and `responses`
+### Include an `APIRouter` with a `prefix`, `tags`, `responses`, and `dependencies`
 
 Now, let's include the router from the `items` submodule.
 
@@ -251,7 +248,9 @@ We can also add a list of `tags` that will be applied to all the *path operation
 
 And we can add predefined `responses` that will be included in all the *path operations* too.
 
-```Python hl_lines="8 9 10 11 12 13"
+And we can add a list of `dependencies` that will be added to all the *path operations* in the router and will be executed/solved for each request made to them.
+
+```Python hl_lines="8 9 10 14 15 16 17 18 19 20"
 {!./src/bigger_applications/app/main.py!}
 ```
 
@@ -262,27 +261,28 @@ The end result is that the item paths are now:
 
 ...as we intended.
 
-They will be marked with a list of tags that contain a single string `"items"`.
+* They will be marked with a list of tags that contain a single string `"items"`.
+* The *path operation* that declared a `"custom"` tag will have both tags, `items` and `custom`.
+    * These "tags" are especially useful for the automatic interactive documentation systems (using OpenAPI).
+* All of them will include the predefined `responses`.
+* The *path operation* that declared a custom `403` response will have both the predefined responses (`404`) and the `403` declared in it directly.
+* All these *path operations* will have the list of `dependencies` evaluated/executed before them.
+    * If you also declare dependencies in a specific *path operation*, **they will be executed too**.
+    * The router dependencies are executed first, then the <a href="https://fastapi.tiangolo.com/tutorial/dependencies/dependencies-in-decorator/" target="_blank">`dependencies` in the decorator</a>, and then the normal parameter dependencies.
+    * You can also add <a href="https://fastapi.tiangolo.com/tutorial/security/oauth2-scopes/" target="_blank">`Security` dependencies with `scopes`</a>.
 
-The *path operation* that declared a `"custom"` tag will have both tags, `items` and `custom`.
-
-These "tags" are especially useful for the automatic interactive documentation systems (using OpenAPI).
-
-And all of them will include the the predefined `responses`.
-
-The *path operation* that declared a custom `403` response will have both the predefined responses (`404`) and the `403` declared in it directly.
+!!! tip
+    Having `dependencies` in a decorator can be used, for example, to require authentication for a whole group of *path operations*. Even if the dependencies are not added individually to each one of them.
 
 !!! check
-    The `prefix`, `tags`, and `responses` parameters are (as in many other cases) just a feature from **FastAPI** to help you avoid code duplication.
-
+    The `prefix`, `tags`, `responses` and `dependencies` parameters are (as in many other cases) just a feature from **FastAPI** to help you avoid code duplication.
 
 !!! tip
     You could also add path operations directly, for example with: `@app.get(...)`.
-    
-    Apart from `app.include_router()`, in the same **FastAPI** app.
-    
-    It would still work the same.
 
+    Apart from `app.include_router()`, in the same **FastAPI** app.
+
+    It would still work the same.
 
 !!! info "Very Technical Details"
     **Note**: this is a very technical detail that you probably can **just skip**.

docs/tutorial/dependencies/advanced-dependencies.md

@@ -22,7 +22,7 @@ Not the class itself (which is already a callable), but an instance of that clas
 To do that, we declare a method `__call__`:
 
 ```Python hl_lines="10"
-{!./src/dependencies/tutorial006.py!}
+{!./src/dependencies/tutorial007.py!}
 ```
 
 In this case, this `__call__` is what **FastAPI** will use to check for additional parameters and sub-dependencies, and this is what will be called to pass a value to the parameter in your *path operation function* later.
@@ -32,7 +32,7 @@ In this case, this `__call__` is what **FastAPI** will use to check for addition
 And now, we can use `__init__` to declare the parameters of the instance that we can use to "parameterize" the dependency:
 
 ```Python hl_lines="7"
-{!./src/dependencies/tutorial006.py!}
+{!./src/dependencies/tutorial007.py!}
 ```
 
 In this case, **FastAPI** won't ever touch or care about `__init__`, we will use it directly in our code.
@@ -42,7 +42,7 @@ In this case, **FastAPI** won't ever touch or care about `__init__`, we will use
 We could create an instance of this class with:
 
 ```Python hl_lines="16"
-{!./src/dependencies/tutorial006.py!}
+{!./src/dependencies/tutorial007.py!}
 ```
 
 And that way we are able to "parameterize" our dependency, that now has `"bar"` inside of it, as the attribute `checker.fixed_content`.
@@ -60,7 +60,7 @@ checker(q="somequery")
 ...and pass whatever that returns as the value of the dependency in our path operation function as the parameter `fixed_content_included`:
 
 ```Python hl_lines="20"
-{!./src/dependencies/tutorial006.py!}
+{!./src/dependencies/tutorial007.py!}
 ```
 
 !!! tip

docs/tutorial/dependencies/dependencies-in-path-operation-decorators.md

@@ -0,0 +1,60 @@
+In some cases you don't really need the return value of a dependency inside your *path operation function*.
+
+Or the dependency doesn't return a value.
+
+But you still need it to be executed/solved.
+
+For those cases, instead of declaring a *path operation function* parameter with `Depends`, you can add a `list` of `dependencies` to the *path operation decorator*.
+
+## Add `dependencies` to the *path operation decorator*
+
+The *path operation decorator* receives an optional argument `dependencies`.
+
+It should be a `list` of `Depends()`:
+
+```Python hl_lines="17"
+{!./src/dependencies/tutorial006.py!}
+```
+
+These dependencies will be executed/solved the same way normal dependencies. But their value (if they return any) won't be passed to your *path operation function*.
+
+!!! tip
+    Some editors check for unused function parameters, and show them as errors.
+
+    Using these `dependencies` in the *path operation decorator* you can make sure they are executed while avoiding editor/tooling errors.
+
+    It might also help avoiding confusion for new developers that see an un-used parameter in your code and could think it's unnecessary.
+
+## Dependencies errors and return values
+
+You can use the same dependency *functions* you use normally.
+
+### Dependency requirements
+
+They can declare request requirements (like headers) or other sub-dependencies:
+
+```Python hl_lines="6 11"
+{!./src/dependencies/tutorial006.py!}
+```
+
+### Raise exceptions
+
+These dependencies can `raise` exceptions, the same as normal dependencies:
+
+```Python hl_lines="8 13"
+{!./src/dependencies/tutorial006.py!}
+```
+
+### Return values
+
+And they can return values or not, the values won't be used.
+
+So, you can re-use a normal dependency (that returns a value) you already use somewhere else, and even though the value won't be used, the dependency will be executed:
+
+```Python hl_lines="9 14"
+{!./src/dependencies/tutorial006.py!}
+```
+
+## Dependencies for a group of *path operations*
+
+Later, when reading about how to <a href="https://fastapi.tiangolo.com/tutorial/bigger-applications/" target="_blank">structure bigger applications</a>, possibly with multiple files, you will learn how to declare a single `dependencies` parameter for a group of *path operations*.

docs/tutorial/security/oauth2-scopes.md

@@ -244,3 +244,7 @@ The most secure is the code flow, but is more complex to implement as it require
     But in the end, they are implementing the same OAuth2 standard.
 
 **FastAPI** includes utilities for all these OAuth2 authentication flows in `fastapi.security.oauth2`.
+
+## `Security` in decorator `dependencies`
+
+The same way you can define a `list` of <a href="https://fastapi.tiangolo.com/tutorial/dependencies/dependencies-in-decorator/" target="_blank">`Depends` in the decorator's `dependencies` parameter</a>, you could also use `Security` with `scopes` there.