Client Reference¶

Client Session¶

Client session is the recommended interface for making HTTP requests.

Session encapsulates a connection pool (connector instance) and supports keepalives by default. Unless you are connecting to a large, unknown number of different servers over the lifetime of your application, it is suggested you use a single session for the lifetime of your application to benefit from connection pooling.

Usage example:

import aiohttp
import asyncio

async def fetch(client):
    async with client.get('http://python.org') as resp:
        assert resp.status == 200
        return await resp.text()

async def main():
    async with aiohttp.ClientSession() as client:
        html = await fetch(client)
        print(html)

loop = asyncio.get_event_loop()
loop.run_until_complete(main())

The client session supports the context manager protocol for self closing.

class aiohttp.ClientSession(base_url=None, *, connector=None, cookies=None, headers=None, skip_auto_headers=None, auth=None, json_serialize=json.dumps, version=aiohttp.HttpVersion11, cookie_jar=None, read_timeout=None, conn_timeout=None, timeout=sentinel, raise_for_status=False, connector_owner=True, auto_decompress=True, read_bufsize=2 ** 16, requote_redirect_url=False, trust_env=False, trace_configs=None)¶

The class for creating client sessions and making requests.

Parameters

base_url –
Base part of the URL (optional) If set it allows to skip the base part in request calls.

New in version 3.8.
connector (aiohttp.BaseConnector) – BaseConnector sub-class instance to support connection pooling.
loop –
event loop used for processing HTTP requests.

If loop is None the constructor borrows it from connector if specified.

asyncio.get_event_loop() is used for getting default event loop otherwise.

Deprecated since version 2.0.
cookies (dict) – Cookies to send with the request (optional)
headers –
HTTP Headers to send with every request (optional).

May be either iterable of key-value pairs or Mapping (e.g. dict, CIMultiDict).
skip_auto_headers –
set of headers for which autogeneration should be skipped.

aiohttp autogenerates headers like User-Agent or Content-Type if these headers are not explicitly passed. Using skip_auto_headers parameter allows to skip that generation. Note that Content-Length autogeneration can’t be skipped.

Iterable of str or istr (optional)
auth (aiohttp.BasicAuth) – an object that represents HTTP Basic Authorization (optional)
version – supported HTTP version, HTTP 1.1 by default.
cookie_jar –
Cookie Jar, AbstractCookieJar instance.

By default every session instance has own private cookie jar for automatic cookies processing but user may redefine this behavior by providing own jar implementation.

One example is not processing cookies at all when working in proxy mode.

If no cookie processing is needed, a aiohttp.DummyCookieJar instance can be provided.
json_serialize (collections.abc.Callable) –
Json serializer callable.

By default json.dumps() function.
raise_for_status (bool) –
Automatically call ClientResponse.raise_for_status() for each response, False by default.

This parameter can be overridden when you making a request, e.g.:
```
client_session = aiohttp.ClientSession(raise_for_status=True)
resp = await client_session.get(url, raise_for_status=False)
async with resp:
    assert resp.status == 200
```
Set the parameter to True if you need raise_for_status for most of cases but override raise_for_status for those requests where you need to handle responses with status 400 or higher.
timeout –

a ClientTimeout settings structure, 300 seconds (5min)
total timeout by default.

New in version 3.3.
read_timeout (float) –
Request operations timeout. read_timeout is cumulative for all request operations (request, redirects, responses, data consuming). By default, the read timeout is 5*60 seconds. Use None or 0 to disable timeout checks.

Deprecated since version 3.3: Use timeout parameter instead.
conn_timeout (float) –
timeout for connection establishing (optional). Values 0 or None mean no timeout.

Deprecated since version 3.3: Use timeout parameter instead.
connector_owner (bool) –
Close connector instance on session closing.

Setting the parameter to False allows to share connection pool between sessions without sharing session state: cookies etc.
auto_decompress (bool) –

Automatically decompress response body,
True by default

New in version 2.3.
read_bufsize (int) –

Size of the read buffer (ClientResponse.content).
64 KiB by default.

New in version 3.7.
trust_env (bool) –
Get proxies information from HTTP_PROXY / HTTPS_PROXY environment variables if the parameter is True (False by default).

Get proxy credentials from ~/.netrc file if present.

See also

.netrc documentation: https://www.gnu.org/software/inetutils/manual/html_node/The-_002enetrc-file.html

New in version 2.3.

Changed in version 3.0: Added support for ~/.netrc file.
requote_redirect_url (bool) –

Apply URL requoting for redirection URLs if
automatic redirection is enabled (True by default).

New in version 3.5.
trace_configs – A list of TraceConfig instances used for client tracing. None (default) is used for request tracing disabling. See Tracing Reference for more information.

closed¶

True if the session has been closed, False otherwise.

A read-only property.

connector¶

aiohttp.BaseConnector derived instance used for the session.

A read-only property.

cookie_jar¶

The session cookies, AbstractCookieJar instance.

Gives access to cookie jar’s content and modifiers.

A read-only property.

requote_redirect_url¶: aiohttp re quote’s redirect urls by default, but some servers require exact url from location header. To disable re-quote system set requote_redirect_url attribute to False.

New in version 2.1.

Note

This parameter affects all subsequent requests.

Deprecated since version 3.5: The attribute modification is deprecated.

loop¶

A loop instance used for session creation.

A read-only property.

Deprecated since version 3.5.

timeout¶: Default client timeouts, ClientTimeout instance. The value can be tuned by passing timeout parameter to ClientSession constructor.

New in version 3.7.

headers¶

HTTP Headers that sent with every request

May be either iterable of key-value pairs or Mapping (e.g. dict, CIMultiDict).

New in version 3.7.

skip_auto_headers¶

Set of headers for which autogeneration skipped.

frozenset of str or istr (optional)

New in version 3.7.

auth¶

An object that represents HTTP Basic Authorization.

BasicAuth (optional)

New in version 3.7.

json_serialize¶

Json serializer callable.

By default json.dumps() function.

New in version 3.7.

connector_owner¶

Should connector be closed on session closing

bool (optional)

New in version 3.7.

raise_for_status¶

Should ClientResponse.raise_for_status() be called for each response

Either bool or collections.abc.Callable

New in version 3.7.

auto_decompress¶

Should the body response be automatically decompressed

bool default is True

New in version 3.7.

trust_env¶

Should get proxies information from HTTP_PROXY / HTTPS_PROXY environment variables or ~/.netrc file if present

bool default is False

New in version 3.7.

trace_config¶: A list of TraceConfig instances used for client tracing. None (default) is used for request tracing disabling. See Tracing Reference for more information.

New in version 3.7.

detach()¶

Detach connector from session without closing the former.

Session is switched to closed state anyway.

Basic API¶

While we encourage ClientSession usage we also provide simple coroutines for making HTTP requests.

Basic API is good for performing simple HTTP requests without keepaliving, cookies and complex connection stuff like properly configured SSL certification chaining.

Connectors¶

Connectors are transports for aiohttp client API.

There are standard connectors:

TCPConnector for regular TCP sockets (both HTTP and HTTPS schemes supported).
UnixConnector for connecting via UNIX socket (it’s used mostly for testing purposes).

All connector classes should be derived from BaseConnector.

By default all connectors support keep-alive connections (behavior is controlled by force_close constructor’s parameter).

BaseConnector¶

class aiohttp.BaseConnector(*, keepalive_timeout=15, force_close=False, limit=100, limit_per_host=0, enable_cleanup_closed=False, loop=None)¶

Base class for all connectors.

Parameters

keepalive_timeout (float) – timeout for connection reusing after releasing (optional). Values 0. For disabling keep-alive feature use force_close=True flag.
limit (int) – total number simultaneous connections. If limit is None the connector has no limit (default: 100).
limit_per_host (int) – limit simultaneous connections to the same endpoint. Endpoints are the same if they are have equal (host, port, is_ssl) triple. If limit is 0 the connector has no limit (default: 0).
force_close (bool) – close underlying sockets after connection releasing (optional).
enable_cleanup_closed (bool) – some SSL servers do not properly complete SSL shutdown process, in that case asyncio leaks ssl connections. If this parameter is set to True, aiohttp additionally aborts underlining transport after 2 seconds. It is off by default.
loop –
event loop used for handling connections. If param is None, asyncio.get_event_loop() is used for getting default event loop.

Deprecated since version 2.0.

closed¶: Read-only property, True if connector is closed.

force_close¶: Read-only property, True if connector should ultimately close connections on releasing.

limit¶: The total number for simultaneous connections. If limit is 0 the connector has no limit. The default limit size is 100.

limit_per_host¶

The limit for simultaneous connections to the same endpoint.

Endpoints are the same if they are have equal (host, port, is_ssl) triple.

If limit_per_host is None the connector has no limit per host.

Read-only property.

TCPConnector¶

class aiohttp.TCPConnector(*, ssl=None, verify_ssl=True, fingerprint=None, use_dns_cache=True, ttl_dns_cache=10, family=0, ssl_context=None, local_addr=None, resolver=None, keepalive_timeout=sentinel, force_close=False, limit=100, limit_per_host=0, enable_cleanup_closed=False, loop=None)¶

Connector for working with HTTP and HTTPS via TCP sockets.

The most common transport. When you don’t know what connector type to use, use a TCPConnector instance.

TCPConnector inherits from BaseConnector.

Constructor accepts all parameters suitable for BaseConnector plus several TCP-specific ones:

param ssl

SSL validation mode. None for default SSL check
(ssl.create_default_context() is used), False for skip SSL certificate validation, aiohttp.Fingerprint for fingerprint validation, ssl.SSLContext for custom SSL certificate validation.

Supersedes verify_ssl, ssl_context and fingerprint parameters.

New in version 3.0.

Parameters

verify_ssl (bool) –
perform SSL certificate validation for HTTPS requests (enabled by default). May be disabled to skip validation for sites with invalid certificates.

Deprecated since version 2.3: Pass verify_ssl to ClientSession.get() etc.
fingerprint (bytes) –
pass the SHA256 digest of the expected certificate in DER format to verify that the certificate the server presents matches. Useful for certificate pinning.

Note: use of MD5 or SHA1 digests is insecure and deprecated.

Deprecated since version 2.3: Pass verify_ssl to ClientSession.get() etc.
use_dns_cache (bool) –
use internal cache for DNS lookups, True by default.

Enabling an option may speedup connection establishing a bit but may introduce some side effects also.
ttl_dns_cache (int) –
expire after some seconds the DNS entries, None means cached forever. By default 10 seconds (optional).

In some environments the IP addresses related to a specific HOST can change after a specific time. Use this option to keep the DNS cache updated refreshing each entry after N seconds.
limit (int) – total number simultaneous connections. If limit is None the connector has no limit (default: 100).
limit_per_host (int) – limit simultaneous connections to the same endpoint. Endpoints are the same if they are have equal (host, port, is_ssl) triple. If limit is 0 the connector has no limit (default: 0).
resolver (aiohttp.abc.AbstractResolver) –
custom resolver instance to use. aiohttp.DefaultResolver by default (asynchronous if aiodns>=1.1 is installed).

Custom resolvers allow to resolve hostnames differently than the way the host is configured.

The resolver is aiohttp.ThreadedResolver by default, asynchronous version is pretty robust but might fail in very rare cases.
family (int) –
TCP socket family, both IPv4 and IPv6 by default. For IPv4 only use socket.AF_INET, for IPv6 only – socket.AF_INET6.

family is 0 by default, that means both IPv4 and IPv6 are accepted. To specify only concrete version please pass socket.AF_INET or socket.AF_INET6 explicitly.
ssl_context (ssl.SSLContext) –
SSL context used for processing HTTPS requests (optional).

ssl_context may be used for configuring certification authority channel, supported SSL options etc.
local_addr (tuple) – tuple of (local_host, local_port) used to bind socket locally if specified.
force_close (bool) – close underlying sockets after connection releasing (optional).
enable_cleanup_closed (bool) – Some ssl servers do not properly complete SSL shutdown process, in that case asyncio leaks SSL connections. If this parameter is set to True, aiohttp additionally aborts underlining transport after 2 seconds. It is off by default.

family¶

TCP socket family e.g. socket.AF_INET or socket.AF_INET6

Read-only property.

dns_cache¶

Use quick lookup in internal DNS cache for host names if True.

Read-only bool property.

cached_hosts¶

The cache of resolved hosts if dns_cache is enabled.

Read-only types.MappingProxyType property.

clear_dns_cache(self, host=None, port=None)¶

Clear internal DNS cache.

Remove specific entry if both host and port are specified, clear all cache otherwise.

UnixConnector¶

class aiohttp.UnixConnector(path, *, conn_timeout=None, keepalive_timeout=30, limit=100, force_close=False, loop=None)¶

Unix socket connector.

Use UnixConnector for sending HTTP/HTTPS requests through UNIX Sockets as underlying transport.

UNIX sockets are handy for writing tests and making very fast connections between processes on the same host.

UnixConnector is inherited from BaseConnector.

Usage:

conn = UnixConnector(path='/path/to/socket')
session = ClientSession(connector=conn)
async with session.get('http://python.org') as resp:
    ...

Constructor accepts all parameters suitable for BaseConnector plus UNIX-specific one:

Parameters: path (str) – Unix socket path

path¶: Path to UNIX socket, read-only str property.

Connection¶

class aiohttp.Connection¶

Encapsulates single connection in connector object.

End user should never create Connection instances manually but get it by BaseConnector.connect() coroutine.

closed¶: bool read-only property, True if connection was closed, released or detached.

loop¶: Event loop used for connection

Deprecated since version 3.5.

transport¶: Connection transport

close()¶: Close connection with forcibly closing underlying socket.

release()¶

Release connection back to connector.

Underlying socket is not closed, the connection may be reused later if timeout (30 seconds by default) for connection was not expired.

Response object¶

class aiohttp.ClientResponse¶

Client response returned by aiohttp.ClientSession.request() and family.

User never creates the instance of ClientResponse class but gets it from API calls.

ClientResponse supports async context manager protocol, e.g.:

resp = await client_session.get(url)
async with resp:
    assert resp.status == 200

After exiting from async with block response object will be released (see release() coroutine).

version¶: Response’s version, HttpVersion instance.

status¶: HTTP status code of response (int), e.g. 200.

reason¶: HTTP status reason of response (str), e.g. "OK".

ok¶: Boolean representation of HTTP status code (bool). True if status is less than 400; otherwise, False.

method¶: Request’s method (str).

url¶: URL of request (URL).

real_url¶: Unmodified URL of request with URL fragment unstripped (URL).

New in version 3.2.

connection¶: Connection used for handling response.

content¶

Payload stream, which contains response’s BODY (StreamReader). It supports various reading methods depending on the expected format. When chunked transfer encoding is used by the server, allows retrieving the actual http chunks.

Reading from the stream may raise aiohttp.ClientPayloadError if the response object is closed before response receives all data or in case if any transfer encoding related errors like misformed chunked encoding of broken compression data.

cookies¶: HTTP cookies of response (Set-Cookie HTTP header, SimpleCookie).

headers¶: A case-insensitive multidict proxy with HTTP headers of response, CIMultiDictProxy.

raw_headers¶: Unmodified HTTP headers of response as unconverted bytes, a sequence of (key, value) pairs.

links¶

Link HTTP header parsed into a MultiDictProxy.

For each link, key is link param rel when it exists, or link url as str otherwise, and value is MultiDictProxy of link params and url at key url as URL instance.

New in version 3.2.

content_type¶: Read-only property with content part of Content-Type header.

Note

Returns value is 'application/octet-stream' if no Content-Type header present in HTTP headers according to RFC 2616. To make sure Content-Type header is not present in the server reply, use headers or raw_headers, e.g. 'CONTENT-TYPE' not in resp.headers.

charset¶

Read-only property that specifies the encoding for the request’s BODY.

The value is parsed from the Content-Type HTTP header.

Returns str like 'utf-8' or None if no Content-Type header present in HTTP headers or it has no charset information.

content_disposition¶

Read-only property that specified the Content-Disposition HTTP header.

Instance of ContentDisposition or None if no Content-Disposition header present in HTTP headers.

history¶: A Sequence of ClientResponse objects of preceding requests (earliest request first) if there were redirects, an empty sequence otherwise.

close()¶

Close response and underlying connection.

For keep-alive support see release().

raise_for_status()¶

Raise an aiohttp.ClientResponseError if the response status is 400 or higher.

Do nothing for success responses (less than 400).

request_info¶: A namedtuple with request URL and headers from ClientRequest object, aiohttp.RequestInfo instance.

get_encoding()¶

Automatically detect content encoding using charset info in Content-Type HTTP header. If this info is not exists or there are no appropriate codecs for encoding then cchardet / charset-normalizer is used.

Beware that it is not always safe to use the result of this function to decode a response. Some encodings detected by cchardet are not known by Python (e.g. VISCII). charset-normalizer is not concerned by that issue.

Raises: RuntimeError – if called before the body has been read, for cchardet usage

New in version 3.0.

ClientWebSocketResponse¶

To connect to a websocket server aiohttp.ws_connect() or aiohttp.ClientSession.ws_connect() coroutines should be used, do not create an instance of class ClientWebSocketResponse manually.

class aiohttp.ClientWebSocketResponse¶

Class for handling client-side websockets.

closed¶: Read-only property, True if close() has been called or CLOSE message has been received from peer.

protocol¶

Websocket subprotocol chosen after start() call.

May be None if server and client protocols are not overlapping.

get_extra_info(name, default=None)¶: Reads extra info from connection’s transport

exception()¶: Returns exception if any occurs or returns None.

Utilities¶

ClientTimeout¶

class aiohttp.ClientTimeout(*, total=None, connect=None, sock_connect=None, sock_read=None)¶

A data class for client timeout settings.

See Timeouts for usage examples.

total¶

Total number of seconds for the whole request.

float, None by default.

connect¶

Maximal number of seconds for acquiring a connection from pool. The time consists connection establishment for a new connection or waiting for a free connection from a pool if pool connection limits are exceeded.

For pure socket connection establishment time use sock_connect.

float, None by default.

sock_connect¶

Maximal number of seconds for connecting to a peer for a new connection, not given from a pool. See also connect.

float, None by default.

sock_read¶

Maximal number of seconds for reading a portion of data from a peer.

float, None by default.

New in version 3.3.

Note

Timeouts larger than 5 seconds are rounded for scheduling on the next second boundary (an absolute time where microseconds part is zero) for the sake of performance.

E.g., assume a timeout is 10, absolute time when timeout should expire is loop.time() + 5, and it points to 12345.67 + 10 which is equal to 12355.67.

The absolute time for the timeout cancellation is 12356.

It leads to grouping all close scheduled timeout expirations to exactly the same time to reduce amount of loop wakeups.

Changed in version 3.7: Rounding to the next seconds boundary is disabled for timeouts smaller than 5 seconds for the sake of easy debugging.

In turn, tiny timeouts can lead to significant performance degradation on production environment.

ETag¶

class aiohttp.ETag(name, is_weak=False)¶

Represents ETag identifier.

value¶: Value of corresponding etag without quotes.

is_weak¶: Flag indicates that etag is weak (has W/ prefix).

New in version 3.8.

RequestInfo¶

class aiohttp.RequestInfo¶

A data class with request URL and headers from ClientRequest object, available as ClientResponse.request_info attribute.

url¶: Requested url, yarl.URL instance.

method¶: Request HTTP method like 'GET' or 'POST', str.

headers¶: HTTP headers for request, multidict.CIMultiDict instance.

real_url¶: Requested url with URL fragment unstripped, yarl.URL instance.

New in version 3.2.

BasicAuth¶

class aiohttp.BasicAuth(login, password='', encoding='latin1')¶

HTTP basic authentication helper.

Parameters

login (str) – login
password (str) – password
encoding (str) – encoding ('latin1' by default)

Should be used for specifying authorization data in client API, e.g. auth parameter for ClientSession.request().

classmethod decode(auth_header, encoding='latin1')¶

Decode HTTP basic authentication credentials.

Parameters

auth_header (str) – The Authorization header to decode.
encoding (str) – (optional) encoding (‘latin1’ by default)

Returns

decoded authentication data, BasicAuth.

classmethod from_url(url)¶

Constructed credentials info from url’s user and password parts.

Returns: credentials data, BasicAuth or None is credentials are not provided.

New in version 2.3.

encode()¶

Encode credentials into string suitable for Authorization header etc.

Returns: encoded authentication data, str.

CookieJar¶

class aiohttp.CookieJar(*, unsafe=False, quote_cookie=True, treat_as_secure_origin=[])¶

The cookie jar instance is available as ClientSession.cookie_jar.

The jar contains Morsel items for storing internal cookie data.

API provides a count of saved cookies:

len(session.cookie_jar)

These cookies may be iterated over:

for cookie in session.cookie_jar:
    print(cookie.key)
    print(cookie["domain"])

The class implements collections.abc.Iterable, collections.abc.Sized and aiohttp.abc.AbstractCookieJar interfaces.

Implements cookie storage adhering to RFC 6265.

Parameters

unsafe (bool) – (optional) Whether to accept cookies from IPs.
quote_cookie (bool) –

(optional) Whether to quote cookies according to
RFC 2109. Some backend systems (not compatible with RFC mentioned above) does not support quoted cookies.

New in version 3.7.
treat_as_secure_origin –
(optional) Mark origins as secure
for cookies marked as Secured. Possible types are

Possible types are:
- tuple or list of str or yarl.URL
- str
- yarl.URL
New in version 3.8.

update_cookies(cookies, response_url=None)¶

Update cookies returned by server in Set-Cookie header.

Parameters

cookies – a collections.abc.Mapping (e.g. dict, SimpleCookie) or iterable of pairs with cookies returned by server’s response.
response_url (URL) – URL of response, None for shared cookies. Regular cookies are coupled with server’s URL and are sent only to this server, shared ones are sent in every client request.

filter_cookies(request_url)¶

Return jar’s cookies acceptable for URL and available in Cookie header for sending client requests for given URL.

Parameters: response_url (URL) – request’s URL for which cookies are asked.
Returns: http.cookies.SimpleCookie with filtered cookies for given URL.

save(file_path)¶

Write a pickled representation of cookies into the file at provided path.

Parameters: file_path – Path to file where cookies will be serialized, str or pathlib.Path instance.

load(file_path)¶

Load a pickled representation of cookies from the file at provided path.

Parameters: file_path – Path to file from where cookies will be imported, str or pathlib.Path instance.

clear(predicate=None)¶

Removes all cookies from the jar if the predicate is None. Otherwise remove only those Morsel that predicate(morsel) returns True.

Parameters

predicate –

callable that gets Morsel as a parameter and returns True if this Morsel must be deleted from the jar.

New in version 4.0.

clear_domain(domain)¶

Remove all cookies from the jar that belongs to the specified domain or its subdomains.

Parameters: domain (str) – domain for which cookies must be deleted from the jar.

New in version 4.0.

class aiohttp.DummyCookieJar(*, loop=None)¶

Dummy cookie jar which does not store cookies but ignores them.

Could be useful e.g. for web crawlers to iterate over Internet without blowing up with saved cookies information.

To install dummy cookie jar pass it into session instance:

jar = aiohttp.DummyCookieJar()
session = aiohttp.ClientSession(cookie_jar=DummyCookieJar())

class aiohttp.Fingerprint(digest)¶

Fingerprint helper for checking SSL certificates by SHA256 digest.

Parameters: digest (bytes) – SHA256 digest for certificate in DER-encoded binary form (see ssl.SSLSocket.getpeercert()).

To check fingerprint pass the object into ClientSession.get() call, e.g.:

import hashlib

with open(path_to_cert, 'rb') as f:
    digest = hashlib.sha256(f.read()).digest()

await session.get(url, ssl=aiohttp.Fingerprint(digest))

New in version 3.0.

FormData¶

A FormData object contains the form data and also handles encoding it into a body that is either multipart/form-data or application/x-www-form-urlencoded. multipart/form-data is used if at least one field is an io.IOBase object or was added with at least one optional argument to add_field (content_type, filename, or content_transfer_encoding). Otherwise, application/x-www-form-urlencoded is used.

FormData instances are callable and return a aiohttp.payload.Payload on being called.

class aiohttp.FormData(fields, quote_fields=True, charset=None)¶

Helper class for multipart/form-data and application/x-www-form-urlencoded body generation.

Parameters

fields –

A container for the key/value pairs of this form.

Possible types are:

dict
tuple or list
io.IOBase, e.g. a file-like object
multidict.MultiDict or multidict.MultiDictProxy

If it is a tuple or list, it must be a valid argument for add_fields.

For dict, multidict.MultiDict, and multidict.MultiDictProxy, the keys and values must be valid name and value arguments to add_field, respectively.

add_field(name, value, content_type=None, filename=None, content_transfer_encoding=None)¶

Add a field to the form.

Parameters

name (str) – Name of the field
value –
Value of the field

Possible types are:
- str
- bytes, bytearray, or memoryview
- io.IOBase, e.g. a file-like object
content_type (str) – The field’s content-type header (optional)
filename (str) –
The field’s filename (optional)

If this is not set and value is a bytes, bytearray, or memoryview object, the name argument is used as the filename unless content_transfer_encoding is specified.

If filename is not set and value is an io.IOBase object, the filename is extracted from the object if possible.
content_transfer_encoding (str) – The field’s content-transfer-encoding header (optional)

add_fields(fields)¶

Add one or more fields to the form.

Parameters

fields –

An iterable containing:

io.IOBase, e.g. a file-like object
multidict.MultiDict or multidict.MultiDictProxy
tuple or list of length two, containing a name-value pair

Client exceptions¶

Exception hierarchy has been significantly modified in version 2.0. aiohttp defines only exceptions that covers connection handling and server response misbehaviors. For developer specific mistakes, aiohttp uses python standard exceptions like ValueError or TypeError.

Reading a response content may raise a ClientPayloadError exception. This exception indicates errors specific to the payload encoding. Such as invalid compressed data, malformed chunked-encoded chunks or not enough data that satisfy the content-length header.

All exceptions are available as members of aiohttp module.

exception aiohttp.ClientError¶

Base class for all client specific exceptions.

Derived from Exception

class aiohttp.ClientPayloadError¶

This exception can only be raised while reading the response payload if one of these errors occurs:

invalid compression
malformed chunked encoding
not enough data that satisfy Content-Length HTTP header.

Derived from ClientError

exception aiohttp.InvalidURL¶

URL used for fetching is malformed, e.g. it does not contain host part.

Derived from ClientError and ValueError

url¶: Invalid URL, yarl.URL instance.

class aiohttp.ContentDisposition¶

Represent Content-Disposition header

value¶

A str instance. Value of Content-Disposition header itself, e.g. attachment.

filename¶

A str instance. Content filename extracted from parameters. May be None.

parameters¶

Read-only mapping contains all parameters.

Response errors¶

exception aiohttp.ClientResponseError¶

These exceptions could happen after we get response from server.

Derived from ClientError

request_info¶: Instance of RequestInfo object, contains information about request.

status¶: HTTP status code of response (int), e.g. 400.

message¶: Message of response (str), e.g. "OK".

headers¶: Headers in response, a list of pairs.

history¶

History from failed response, if available, else empty tuple.

A tuple of ClientResponse objects used for handle redirection responses.

code¶: HTTP status code of response (int), e.g. 400.

Deprecated since version 3.1.

class aiohttp.WSServerHandshakeError¶

Web socket server response error.

Derived from ClientResponseError

class aiohttp.ContentTypeError¶

Invalid content type.

Derived from ClientResponseError

New in version 2.3.

class aiohttp.TooManyRedirects¶

Client was redirected too many times.

Maximum number of redirects can be configured by using parameter max_redirects in request.

Derived from ClientResponseError

New in version 3.2.

Connection errors¶

class aiohttp.ClientConnectionError¶

These exceptions related to low-level connection problems.

Derived from ClientError

class aiohttp.ClientOSError¶

Subset of connection errors that are initiated by an OSError exception.

Derived from ClientConnectionError and OSError

class aiohttp.ClientConnectorError¶

Connector related exceptions.

Derived from ClientOSError

class aiohttp.ClientProxyConnectionError¶: Derived from ClientConnectorError

class aiohttp.UnixClientConnectorError¶: Derived from ClientConnectorError

class aiohttp.ServerConnectionError¶: Derived from ClientConnectionError

class aiohttp.ClientSSLError¶: Derived from ClientConnectorError

class aiohttp.ClientConnectorSSLError¶

Response ssl error.

Derived from ClientSSLError and ssl.SSLError

class aiohttp.ClientConnectorCertificateError¶

Response certificate error.

Derived from ClientSSLError and ssl.CertificateError

class aiohttp.ServerDisconnectedError¶

Server disconnected.

Derived from ServerConnectionError

message¶: Partially parsed HTTP message (optional).

class aiohttp.ServerTimeoutError¶

Server operation timeout: read timeout, etc.

Derived from ServerConnectionError and asyncio.TimeoutError

class aiohttp.ServerFingerprintMismatch¶

Server fingerprint mismatch.

Derived from ServerConnectionError

Hierarchy of exceptions¶

ClientError