2018-08-30 12:53:37 +00:00
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2018-10-02 10:26:19 +00:00
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Starlette includes the classes `HTTPEndpoint` and `WebSocketEndpoint` that provide a class-based view pattern for
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handling HTTP method dispatching and WebSocket sessions.
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### HTTPEndpoint
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2018-08-30 12:53:37 +00:00
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2018-09-05 09:29:04 +00:00
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The `HTTPEndpoint` class can be used as an ASGI application:
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2018-08-30 12:53:37 +00:00
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```python
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2018-09-05 09:29:04 +00:00
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from starlette.responses import PlainTextResponse
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from starlette.endpoints import HTTPEndpoint
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2018-09-05 09:29:04 +00:00
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class App(HTTPEndpoint):
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async def get(self, request):
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return PlainTextResponse(f"Hello, world!")
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```
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If you're using a Starlette application instance to handle routing, you can
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dispatch to an `HTTPEndpoint` class by using the `@app.route()` decorator, or the
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2018-08-30 12:53:37 +00:00
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`app.add_route()` function. Make sure to dispatch to the class itself, rather
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than to an instance of the class:
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```python
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2018-09-05 11:50:00 +00:00
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from starlette.applications import Starlette
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from starlette.responses import PlainTextResponse
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2018-09-05 09:29:04 +00:00
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from starlette.endpoints import HTTPEndpoint
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2018-08-30 12:53:37 +00:00
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2018-09-05 09:29:04 +00:00
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app = Starlette()
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2018-08-30 12:53:37 +00:00
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@app.route("/")
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class Homepage(HTTPEndpoint):
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async def get(self, request):
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return PlainTextResponse(f"Hello, world!")
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@app.route("/{username}")
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class User(HTTPEndpoint):
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async def get(self, request, username):
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return PlainTextResponse(f"Hello, {username}")
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```
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2018-09-05 09:29:04 +00:00
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HTTP endpoint classes will respond with "405 Method not allowed" responses for any
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request methods which do not map to a corresponding handler.
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2018-10-02 10:26:19 +00:00
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### WebSocketEndpoint
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The `WebSocketEndpoint` class is an ASGI application that presents a wrapper around
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the functionality of a `WebSocket` instance.
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The ASGI connection scope is accessible on the endpoint instance via `.scope` and
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has an attribute `encoding` which may optionally be set, in order to validate the expected websocket data in the `on_receive` method.
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The encoding types are:
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2018-10-02 10:30:54 +00:00
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* `'json'`
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* `'bytes'`
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* `'text'`
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There are three overridable methods for handling specific ASGI websocket message types:
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* `async def on_connect(websocket, **kwargs)`
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* `async def on_receive(websocket, data)`
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* `async def on_disconnect(websocket, close_code)`
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```python
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from starlette.endpoints import WebSocketEndpoint
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class App(WebSocketEndpoint):
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encoding = 'bytes'
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async def on_connect(self, websocket, **kwargs):
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await websocket.accept()
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async def on_receive(self, websocket, data):
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await websocket.send_bytes(b"Message: " + data)
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async def on_disconnect(self, websocket, close_code):
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pass
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```
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The `WebSocketEndpoint` can also be used with the `Starlette` application class:
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```python
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import uvicorn
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from starlette.applications import Starlette
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from starlette.endpoints import WebSocketEndpoint, HTTPEndpoint
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from starlette.responses import HTMLResponse
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app = Starlette()
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html = """
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<!DOCTYPE html>
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<html>
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<head>
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<title>Chat</title>
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</head>
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<body>
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<h1>WebSocket Chat</h1>
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<form action="" onsubmit="sendMessage(event)">
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<input type="text" id="messageText" autocomplete="off"/>
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<button>Send</button>
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</form>
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<ul id='messages'>
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</ul>
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<script>
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var ws = new WebSocket("ws://localhost:8000/ws");
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ws.onmessage = function(event) {
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var messages = document.getElementById('messages')
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var message = document.createElement('li')
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var content = document.createTextNode(event.data)
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message.appendChild(content)
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messages.appendChild(message)
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};
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function sendMessage(event) {
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var input = document.getElementById("messageText")
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ws.send(input.value)
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input.value = ''
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event.preventDefault()
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}
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</script>
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</body>
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</html>
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"""
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@app.route("/")
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class Homepage(HTTPEndpoint):
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async def get(self, request):
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return HTMLResponse(html)
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@app.websocket_route("/ws")
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class Echo(WebSocketEndpoint):
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encoding = "text"
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async def on_receive(self, websocket, data):
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await websocket.send_text(f"Message text was: {data}")
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if __name__ == "__main__":
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uvicorn.run(app, host="0.0.0.0", port=8000)
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```
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