New in version 0.10.
For implementing web server at first create request handler.
Handler is a coroutine or regular function that accepts only request parameter of type Request and returns Response instance:
import asyncio
from aiohttp import web
@asyncio.coroutine
def hello(request):
return web.Response(request, b"Hello, world")
Next you have to create Application instance and register handler in application’s router pointing HTTP method, path and handler:
app = web.Application()
app.router.add_route('GET', '/', hello)
After that create server and run asyncio loop as usual:
loop = asyncio.get_event_loop()
f = loop.create_server(app.make_handler, '0.0.0.0', 8080)
srv = loop.run_until_complete(f)
print('serving on', srv.sockets[0].getsockname())
try:
loop.run_forever()
except KeyboardInterrupt:
pass
That’s it.
Handler is an any callable that accepts single Request argument and returns StreamResponse derived (e.g. Response) instance.
Handler can be a coroutine, aiohttp.web will unyield returned result by applying yield from to handler.
Handlers connected to Application via routes:
handler = Handler()
app.router.add_route('GET', '/', handler)
You can also use variable routes. If route contains string like '/a/{name}/c' that means the route matches to path like '/a/b/c' or '/a/1/c'.
Parsed path part will be available in request handler as request.match_info['name']:
@asyncio.coroutine
def variable_handler(request):
return web.Response(
request,
"Hello, {}".format(request.match_info['name']).encode('utf8'))
app.router.add_route('GET', '/{name}', variable_handler)
Handlers can be first-class functions like:
@asyncio.coroutine
def hello(request):
return web.Response(request, b"Hello, world")
app.router.add_route('GET', '/', hello)
Sometimes you would like to group logically coupled handlers into python class.
aiohttp.web doesn’t dictate any implementation details, application developer can use classes if he want:
class Handler:
def __init__(self):
pass
def handle_intro(self, request):
return web.Response(request, b"Hello, world")
@asyncio.coroutine
def handle_greeting(self, request):
name = request.match_info.get('name')
txt = "Hello, {}".format(name)
return web.Response(request, txt.encode('utf-8')
handler = Handler()
app.router.add_route('GET', '/intro', handler.handle_intro)
app.router.add_route('GET', '/greet/{name}', handler.handle_greeting)
There are two parts necessary for handling file uploads. The first is to make sure you have a form that’s been setup correctly to accept files. This means adding enctype attribute to your form element with the value of multipart/form-data. A very simple example would be a form that accepts an mp3 file. Notice we’ve setup the form as previously explained and also added an input element of the file type:
<form action="/store_mp3" method="post" accept-charset="utf-8"
enctype="multipart/form-data">
<label for="mp3">Mp3</label>
<input id="mp3" name="mp3" type="file" value="" />
<input type="submit" value="submit" />
</form>
The second part is handling the file upload in your request handler (above, assumed to answer on /store_mp3). The uploaded file is added to the request object as a FileField object accessible through the Request.POST() coroutine. The two properties we’re interested in are the file and filename and we’ll use those to read file name and content:
import os
import uuid
from pyramid.response import Response
def store_mp3_view(request):
data = yield from request.POST()
# ``filename`` contains the name of the file in string format.
filename = data['mp3'].filename
# ``input_file`` contains the actual file data which needs to be
# stored somewhere.
input_file = data['mp3'].file
content = input_file.read()
return aiohttp.web.Response(request, content,
headers=MultiDict([('CONTENT-DISPOSITION', input-file)])
Request object contains all information about incoming HTTP request.
Every handler accepts request instance as first positional parameter.
Note
You should never create Request instance by hands – aiohttp.web does it for you.
HTTP method, read only property.
The value is upper-cased str like "GET", "POST", "PUT" etc.
HTTP version of request, read only property.
Returns aiohttp.protocol.HttpVersion instance.
HOST header of request, read only property.
Returns str or None if HTTP request has no HOST header.
The URL including PATH_INFO and the query string. e.g, /app/blog?id=10
Read only str property.
The URL including PATH INFO without the host or scheme. e.g., /app/blog
Read only str property.
A multidict with all the variables in the query string.
Read only MultiDict lazy property.
A case-insensitive multidict with all headers.
Read only CaseInsensitiveMultiDict lazy property.
True if keep-alive connection enabled by HTTP client and protocol version supports it, otherwise False.
Read only bool property.
Read only property with AbstractMatchInfo instance for result of route resolving.
Note
Exact type of property depends on used router. If app.router is UrlDispatcher the property contains UrlMappingMatchInfo instance.
An Application instance used to call request handler, read only property.
An transport used to process request, read only property.
The property can be used, for example, for getting IP address of client peer:
peername = request.transport.get_extra('peername')
if peername is not None:
host, port = peername
A multidict of all request’s cookies.
Read only MultiDict lazy property.
A FlowControlStreamReader instance, input stream for reading request’s BODY.
Read only property.
Read only property with content part of Content-Type header.
Returns str like 'text/html'
Note
Returns value is 'application/octet-stream' if no Content-Type header present in HTTP headers according to RFC 2616
Read only property that specifies encoding for request BODY.
The value is parsed from Content-Type HTTP header.
Returns str like 'utf-8' or None if Content-Type has no charset information.
Read only property that returns length of request BODY.
The value is parsed from Content-Length HTTP header.
Returns int or None if Content-Length is absent.
Read request body, returns bytes object with body content.
The method is a coroutine.
Warning
The method doesn’t store read data internally, subsequent read() call will return empty bytes b''.
Read request body, decode it using charset encoding or UTF-8 if no encoding was specified in MIME-type.
Returns str with body content.
The method is a coroutine.
Warning
The method doesn’t store read data internally, subsequent text() call will return empty string ''.
Read request body decoded as json.
The method is just a boilerplate coroutine implemented as:
@asyncio.coroutine
def json(self, *, loader=json.loads):
body = yield from self.text()
return loader(body)
Parameters: | loader (callable) – any callable that accepts str and returns dict with parsed JSON (json.loads() by default). |
---|
Warning
The method doesn’t store read data internally, subsequent json() call will raise an exception.
A coroutine that reads POST parameters from request body.
Returns MultiDict instance filled with parsed data.
If method is not POST, PUT or PATCH or content_type is not empty or application/x-www-form-urlencoded or multipart/form-data returns empty multidict.
Warning
The method does store read data internally, subsequent POST() call will return the same value.
Release request.
Eat unread part of HTTP BODY if present.
The method is a coroutine.
Note
User code may never call release(), all required work will be processed by aiohttp.web internal machinery.
For now aiohttp.web has two classes for HTTP response: StreamResponse and Response.
Usually you need to use the second one. StreamResponse intended for streaming data, Response contains HTTP BODY as attribute and sends own content as single piece with correct Content-Length HTTP header.
For sake of design decisions Response is derived from StreamResponse parent class.
The response supports keep-alive handling out-of-the-box if request supports it.
You can disable keep-alive by force_close() though.
The common case for sending answer from web handler is returning Response instance:
def handler(request):
return Response(request, "All right!")
The base class for HTTP response handling.
Contains methods for setting HTTP response headers, cookies, response status code, writing HTTP response BODY and so on.
The most important thing you should know about response — it is Finite State Machine.
That means you can do any manipulations on headers, cookies and status code only before send_headers() called.
Once you call send_headers() or write() any change of HTTP header part will raise RuntimeError exception.
Any write() call after write_eof() is forbidden also.
Parameters: |
|
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Read-only property, copy of Request.keep_alive by default.
Can be switched to False by force_close() call.
Disable keep_alive for connection. There are no ways to enable it back.
An instance of http.cookies.SimpleCookie for outgoing cookies.
Warning
Direct setting up Set-Cookie header may be overwritten by explicit calls to cookie manipulation.
We are encourage using of cookies and set_cookie(), del_cookie() for cookie manipulations.
Convenient way for setting cookies, allows to point additional cookie properties like max_age in single call.
Parameters: |
|
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Deletes cookie.
Parameters: |
---|
Send HTTP header. You should not change any header data after calling the method.
Send byte-ish data as part of response BODY.
Calls send_headers() if not been called.
Raises TypeError if data is not bytes, bytearray or memoryview instance.
Raises RuntimeError if write_eof() has been called.
A coroutine may be called as mark of finish HTTP response processing.
Internal machinery will call the method at the end of request processing if needed.
After write_eof() call any manipulations with response object are forbidden.
The most usable response class, inherited from StreamResponse.
Accepts body argument for setting HTTP response BODY.
Actual body sending is done in overridden write_eof().
Parameters: |
|
---|
Read-write attribute for storing response’s content aka BODY, bytes.
Setting body also recalculates content_length value.
Resetting body (assigning None) set content_length to None also, dropping Content-Length HTTP header.
Application is a synonym for web-server.
To get fully working example you have to make application, register supported url in router and create server socket with make_handler() as protocol factory.
Application contains router instance and list of callbacks that will be called on application finishing.
Application is a dict, so you can use it as registry for arbitrary properies for later acceess to registered values from handler via Request.app property:
app = Application(loop=loop)
app['database'] = yield from aiopg.create_engine(**db_config)
@asyncio.coroutine
def handler(request):
with (yield from request.app['database']) as conn:
conn.execute("DELETE * FROM table")
The class inherits dict.
Parameters: |
|
---|
Readonly property that returns event loop.
Creates HTTP protocol for handling requests.
You should never call the method by hands but pass it to create_server() instead as protocol_factory parameter like:
loop = asyncio.get_event_loop()
app = Application(loop=loop)
# setup route table
# app.router.add_route(...)
yield from loop.create_server(app.make_handler, '0.0.0.0', 8080)
A coroutine that should be called after on server stopping.
The method executes functions registered by register_on_finish() in LIFO order.
If callback raises exception the error will be stored by call_exception_handler() with keys: message, exception, application.
Register func as a function to be executed at termination. Any optional arguments that are to be passed to func must be passed as arguments to register_on_finish(). It is possible to register the same function and arguments more than once.
At call of finish() all functions registered are called in last in, first out order.
func may be either regular function or coroutine, finish() will un-yield (yield from) the later.
For dispatching URLs to handlers aiohttp.web uses routers.
Router is any object that implements AbstractRouter interface.
aiohttp.web provides single implementation called UrlDispatcher.
Application uses UrlDispatcher as router() by default.
Straightforward url-mathing router.
Before running Application you should to fill route table first by add_route() and add_static() calls.
Handler lookup is performed by iterating on added routes in FIFO order. The first matching route will be used to call corresponding handler.
Append handler to end of route table.
Parameters: |
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Adds router for returning static files.
Useful for handling static content like images, java script and css files.
Warning
Use add_static() for development only, in production static content usually processed by web servers like nginx or apache.
Parameters: |
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A namedtuple() that returned as multidict value by Request.POST() if field is uploaded file.
Field name
File name as specified by uploading (client) side.
MIME type of uploaded file, 'text/plain' by default.
See also
aiohttp.web defines exceptions for list of HTTP status codes.
Each class relates to a single HTTP status code. Each class is a subclass of the HTTPException.
Those exceptions are derived from Response also, so you can eighter return exception object from Handler or raise it.
The follow snippets are equals:
@asyncio.coroutine
def handler(request):
return aiohttp.web.HTTPFound(request, '/redirect')
and:
@asyncio.coroutine
def handler(request):
raise aiohttp.web.HTTPFound(request, '/redirect')
Each exception class has a status code according to RFC 2068: codes with 100-300 are not really errors; 400s are client errors, and 500s are server errors.
Http Exception hierarchy chart:
Exception
HTTPException
HTTPSuccessful
* 200 - HTTPOk
* 201 - HTTPCreated
* 202 - HTTPAccepted
* 203 - HTTPNonAuthoritativeInformation
* 204 - HTTPNoContent
* 205 - HTTPResetContent
* 206 - HTTPPartialContent
HTTPRedirection
* 300 - HTTPMultipleChoices
* 301 - HTTPMovedPermanently
* 302 - HTTPFound
* 303 - HTTPSeeOther
* 304 - HTTPNotModified
* 305 - HTTPUseProxy
* 307 - HTTPTemporaryRedirect
HTTPError
HTTPClientError
* 400 - HTTPBadRequest
* 401 - HTTPUnauthorized
* 402 - HTTPPaymentRequired
* 403 - HTTPForbidden
* 404 - HTTPNotFound
* 405 - HTTPMethodNotAllowed
* 406 - HTTPNotAcceptable
* 407 - HTTPProxyAuthenticationRequired
* 408 - HTTPRequestTimeout
* 409 - HTTPConflict
* 410 - HTTPGone
* 411 - HTTPLengthRequired
* 412 - HTTPPreconditionFailed
* 413 - HTTPRequestEntityTooLarge
* 414 - HTTPRequestURITooLong
* 415 - HTTPUnsupportedMediaType
* 416 - HTTPRequestRangeNotSatisfiable
* 417 - HTTPExpectationFailed
HTTPServerError
* 500 - HTTPInternalServerError
* 501 - HTTPNotImplemented
* 502 - HTTPBadGateway
* 503 - HTTPServiceUnavailable
* 504 - HTTPGatewayTimeout
* 505 - HTTPVersionNotSupported
All http exceptions has constructor like:
HTTPNotFound(request, *, headers=None, reason=None)
if other not directly specified. headers will be added to default response headers.
Classes HTTPMultipleChoices, HTTPMovedPermanently, HTTPFound, HTTPSeeOther, HTTPUseProxy, HTTPTemporaryRedirect has constructor signature like:
HTTPFound(request, location, *, headers=None, reason=None)
where location is value for Location HTTP header.
HTTPMethodNotAllowed constructed with pointing trial method and list of allowed methods:
HTTPMethodNotAllowed(request, method, allowed_methods, *, headers=None, reason=None)