✨ Add events docs and tests (#99)

.gitignore

@@ -11,3 +11,4 @@ site
 coverage.xml
 .netlify
 test.db
+log.txt

docs/src/events/tutorial001.py

@@ -0,0 +1,16 @@
+from fastapi import FastAPI
+
+app = FastAPI()
+
+items = {}
+
+
+@app.on_event("startup")
+async def startup_event():
+    items["foo"] = {"name": "Fighters"}
+    items["bar"] = {"name": "Tenders"}
+
+
+@app.get("/items/{item_id}")
+async def read_item(item_id: str):
+    return items[item_id]

docs/src/events/tutorial002.py

@@ -0,0 +1,14 @@
+from fastapi import FastAPI
+
+app = FastAPI()
+
+
+@app.on_event("shutdown")
+def startup_event():
+    with open("log.txt", mode="a") as log:
+        log.write("Application shutdown")
+
+
+@app.get("/items/")
+async def read_items():
+    return [{"name": "Foo"}]

docs/tutorial/events.md

@@ -0,0 +1,43 @@
+
+You can define event handlers (functions) that need to be executed before the application starts up, or when the application is shutting down.
+
+These functions can be declared with `async def` or normal `def`.
+
+## `startup` event
+
+To add a function that should be run before the application starts, declare it with the event `"startup"`:
+
+```Python hl_lines="8"
+{!./src/events/tutorial001.py!}
+```
+
+In this case, the `startup` event handler function will initialize the items "database" (just a `dict`) with some values.
+
+You can add more than one event handler function.
+
+And your application won't start receiving requests until all the `startup` event handlers have completed.
+
+## `shutdown` event
+
+To add a function that should be run when the application is shutting down, declare it with the event `"shutdown"`:
+
+```Python hl_lines="6"
+{!./src/events/tutorial002.py!}
+```
+
+Here, the `shutdown` event handler function will write a text line `"Application shutdown"` to a file `log.txt`.
+
+!!! info
+    In the `open()` function, the `mode="a"` means "append", so, the line will be added after whatever is on that file, without overwriting the previous contents.
+
+!!! tip
+    Notice that in this case we are using a standard Python `open()` function that interacts with a file.
+    
+    So, it involves I/O (input/output), that requires "waiting" for things to be written to disk.
+    
+    But `open()` doesn't use `async` and `await`.
+    
+    So, we declare the event handler function with standard `def` instead of `async def`.
+
+!!! info
+    You can read more about these event handlers in <a href="https://www.starlette.io/events/" target="_blank">Starlette's  Events' docs</a>.

mkdocs.yml

@@ -63,6 +63,7 @@ nav:
         - Application Configuration: 'tutorial/application-configuration.md'
         - GraphQL: 'tutorial/graphql.md'
         - WebSockets: 'tutorial/websockets.md'
+        - 'Events: startup - shutdown': 'tutorial/events.md'
         - Debugging: 'tutorial/debugging.md'
     - Concurrency and async / await: 'async.md'
     - Deployment: 'deployment.md'

tests/test_tutorial/test_events/test_tutorial001.py

@@ -0,0 +1,79 @@
+from starlette.testclient import TestClient
+
+from events.tutorial001 import app
+
+openapi_schema = {
+    "openapi": "3.0.2",
+    "info": {"title": "Fast API", "version": "0.1.0"},
+    "paths": {
+        "/items/{item_id}": {
+            "get": {
+                "responses": {
+                    "200": {
+                        "description": "Successful Response",
+                        "content": {"application/json": {"schema": {}}},
+                    },
+                    "422": {
+                        "description": "Validation Error",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "$ref": "#/components/schemas/HTTPValidationError"
+                                }
+                            }
+                        },
+                    },
+                },
+                "summary": "Read Item Get",
+                "operationId": "read_item_items__item_id__get",
+                "parameters": [
+                    {
+                        "required": True,
+                        "schema": {"title": "Item_Id", "type": "string"},
+                        "name": "item_id",
+                        "in": "path",
+                    }
+                ],
+            }
+        }
+    },
+    "components": {
+        "schemas": {
+            "ValidationError": {
+                "title": "ValidationError",
+                "required": ["loc", "msg", "type"],
+                "type": "object",
+                "properties": {
+                    "loc": {
+                        "title": "Location",
+                        "type": "array",
+                        "items": {"type": "string"},
+                    },
+                    "msg": {"title": "Message", "type": "string"},
+                    "type": {"title": "Error Type", "type": "string"},
+                },
+            },
+            "HTTPValidationError": {
+                "title": "HTTPValidationError",
+                "type": "object",
+                "properties": {
+                    "detail": {
+                        "title": "Detail",
+                        "type": "array",
+                        "items": {"$ref": "#/components/schemas/ValidationError"},
+                    }
+                },
+            },
+        }
+    },
+}
+
+
+def test_events():
+    with TestClient(app) as client:
+        response = client.get("/openapi.json")
+        assert response.status_code == 200
+        assert response.json() == openapi_schema
+        response = client.get("/items/foo")
+        assert response.status_code == 200
+        assert response.json() == {"name": "Fighters"}

tests/test_tutorial/test_events/test_tutorial002.py

@@ -0,0 +1,34 @@
+from starlette.testclient import TestClient
+
+from events.tutorial002 import app
+
+openapi_schema = {
+    "openapi": "3.0.2",
+    "info": {"title": "Fast API", "version": "0.1.0"},
+    "paths": {
+        "/items/": {
+            "get": {
+                "responses": {
+                    "200": {
+                        "description": "Successful Response",
+                        "content": {"application/json": {"schema": {}}},
+                    }
+                },
+                "summary": "Read Items Get",
+                "operationId": "read_items_items__get",
+            }
+        }
+    },
+}
+
+
+def test_events():
+    with TestClient(app) as client:
+        response = client.get("/openapi.json")
+        assert response.status_code == 200
+        assert response.json() == openapi_schema
+        response = client.get("/items/")
+        assert response.status_code == 200
+        assert response.json() == [{"name": "Foo"}]
+    with open("log.txt") as log:
+        assert "Application shutdown" in log.read()