44 KiB
Requests and Responses
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.. module:: scrapy.http :synopsis: Request and Response classes
Scrapy uses :class:`~scrapy.Request` and :class:`Response` objects for crawling web sites.
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Unknown interpreted text role "class".Typically, :class:`~scrapy.Request` objects are generated in the spiders and pass across the system until they reach the Downloader, which executes the request and returns a :class:`Response` object which travels back to the spider that issued the request.
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Unknown interpreted text role "class".Both :class:`~scrapy.Request` and :class:`Response` classes have subclasses which add functionality not required in the base classes. These are described below in :ref:`topics-request-response-ref-request-subclasses` and :ref:`topics-request-response-ref-response-subclasses`.
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.. autoclass:: scrapy.Request
:param url: the URL of this request
If the URL is invalid, a :exc:`ValueError` exception is raised.
:type url: str
:param callback: sets :attr:`callback`, defaults to ``None``.
:type callback: Callable[Concatenate[Response, ...], Any] | None
:param method: the HTTP method of this request. Defaults to ``'GET'``.
:type method: str
:param meta: the initial values for the :attr:`.Request.meta` attribute. If
given, the dict passed in this parameter will be shallow copied.
:type meta: dict
:param body: the request body. If a string is passed, then it's encoded as
bytes using the ``encoding`` passed (which defaults to ``utf-8``). If
``body`` is not given, an empty bytes object is stored. Regardless of the
type of this argument, the final value stored will be a bytes object
(never a string or ``None``).
:type body: bytes or str
:param headers: the headers of this request. The dict values can be strings
(for single valued headers) or lists (for multi-valued headers). If
``None`` is passed as value, the HTTP header will not be sent at all.
.. caution:: Cookies set via the ``Cookie`` header are not considered by the
:ref:`cookies-mw`. If you need to set cookies for a request, use the
``cookies`` argument. This is a known current limitation that is being
worked on.
:type headers: dict
:param cookies: the request cookies. These can be sent in two forms.
.. invisible-code-block: python
from scrapy import Request
1. Using a dict:
.. code-block:: python
request_with_cookies = Request(
url="http://www.example.com",
cookies={"currency": "USD", "country": "UY"},
)
2. Using a list of dicts:
.. code-block:: python
request_with_cookies = Request(
url="https://www.example.com",
cookies=[
{
"name": "currency",
"value": "USD",
"domain": "example.com",
"path": "/currency",
"secure": True,
},
],
)
The latter form allows for customizing the ``domain`` and ``path``
attributes of the cookie. This is only useful if the cookies are saved
for later requests.
.. reqmeta:: dont_merge_cookies
When some site returns cookies (in a response) those are stored in the
cookies for that domain and will be sent again in future requests.
That's the typical behaviour of any regular web browser.
Note that setting the :reqmeta:`dont_merge_cookies` key to ``True`` in
:attr:`request.meta <scrapy.Request.meta>` causes custom cookies to be
ignored.
For more info see :ref:`cookies-mw`.
.. caution:: Cookies set via the ``Cookie`` header are not considered by the
:ref:`cookies-mw`. If you need to set cookies for a request, use the
:class:`scrapy.Request.cookies <scrapy.Request>` parameter. This is a known
current limitation that is being worked on.
:type cookies: dict or list
:param encoding: the encoding of this request (defaults to ``'utf-8'``).
This encoding will be used to percent-encode the URL and to convert the
body to bytes (if given as a string).
To disable URL percent-encoding for a request, use the
:reqmeta:`verbatim_url` request meta key.
:type encoding: str
:param priority: sets :attr:`priority`, defaults to ``0``.
:type priority: int
:param dont_filter: sets :attr:`dont_filter`, defaults to ``False``.
:type dont_filter: bool
:param errback: sets :attr:`errback`, defaults to ``None``.
:type errback: Callable[[Failure], Any] | None
:param flags: Flags sent to the request, can be used for logging or similar purposes.
:type flags: list
:param cb_kwargs: A dict with arbitrary data that will be passed as keyword arguments to the Request's callback.
:type cb_kwargs: dict
.. attribute:: Request.url
A string containing the URL of this request.
Keep in mind that this attribute contains the escaped URL, so it can
differ from the URL passed in the ``__init__()`` method.
If :reqmeta:`verbatim_url` is set to ``True``, the URL is kept as
passed to ``__init__()``.
This attribute is read-only. To change the URL of a Request use
:meth:`replace`.
.. attribute:: Request.method
A string representing the HTTP method in the request. This is guaranteed to
be uppercase. Example: ``"GET"``, ``"POST"``, ``"PUT"``, etc
.. attribute:: Request.headers
A dictionary-like (:class:`scrapy.http.headers.Headers`) object which contains
the request headers.
.. attribute:: Request.body
The request body as bytes.
This attribute is read-only. To change the body of a Request use
:meth:`replace`.
.. autoattribute:: callback
.. autoattribute:: errback
.. autoattribute:: priority
.. attribute:: Request.cb_kwargs
A dictionary that contains arbitrary metadata for this request. Its contents
will be passed to the Request's callback as keyword arguments. It is empty
for new Requests, which means by default callbacks only get a
:class:`~scrapy.http.Response` object as argument.
This dict is :doc:`shallow copied <library/copy>` when the request is
cloned using the ``copy()`` or ``replace()`` methods, and can also be
accessed, in your spider, from the ``response.cb_kwargs`` attribute.
In case of a failure to process the request, this dict can be accessed as
``failure.request.cb_kwargs`` in the request's errback. For more information,
see :ref:`errback-cb_kwargs`.
.. note:: When :setting:`JOBDIR` is set, requests are serialized to disk
with :mod:`pickle` (see :ref:`request-serialization`). As a result,
the callback receives a deep copy of any object stored in
``cb_kwargs``, so mutating such an object in the callback does not
affect the original. Avoid relying on shared mutable state passed
through ``cb_kwargs`` in that case.
.. attribute:: Request.meta
:value: {}
A dictionary of arbitrary metadata for the request.
You may extend request metadata as you see fit.
Request metadata can also be accessed through the
:attr:`~scrapy.http.Response.meta` attribute of a response.
To pass data from one spider callback to another, consider using
:attr:`cb_kwargs` instead. However, request metadata may be the right
choice in certain scenarios, such as to maintain some debugging data
across all follow-up requests (e.g. the source URL).
A common use of request metadata is to define request-specific
parameters for Scrapy components (extensions, middlewares, etc.). For
example, if you set ``dont_retry`` to ``True``,
:class:`~scrapy.downloadermiddlewares.retry.RetryMiddleware` will never
retry that request, even if it fails. See :ref:`topics-request-meta`.
You may also use request metadata in your custom Scrapy components, for
example, to keep request state information relevant to your component.
For example,
:class:`~scrapy.downloadermiddlewares.retry.RetryMiddleware` uses the
``retry_times`` metadata key to keep track of how many times a request
has been retried so far.
Copying all the metadata of a previous request into a new, follow-up
request in a spider callback is a bad practice, because request
metadata may include metadata set by Scrapy components that is not
meant to be copied into other requests. For example, copying the
``retry_times`` metadata key into follow-up requests can lower the
amount of retries allowed for those follow-up requests.
You should only copy all request metadata from one request to another
if the new request is meant to replace the old request, as is often the
case when returning a request from a :ref:`downloader middleware
<topics-downloader-middleware>` method.
Also mind that the :meth:`copy` and :meth:`replace` request methods
:doc:`shallow-copy <library/copy>` request metadata.
.. autoattribute:: dont_filter
.. autoattribute:: Request.attributes
.. method:: Request.copy()
Return a new Request which is a copy of this Request. See also:
:ref:`topics-request-response-ref-request-callback-arguments`.
.. method:: Request.replace([url, method, headers, body, cookies, meta, flags, encoding, priority, dont_filter, callback, errback, cb_kwargs, cls])
Return a Request object with the same members, except for those members
given new values by whichever keyword arguments are specified. The
:attr:`~scrapy.Request.cb_kwargs` and :attr:`~scrapy.Request.meta` attributes are shallow
copied by default (unless new values are given as arguments). See also
:ref:`topics-request-response-ref-request-callback-arguments`.
.. automethod:: from_curl
.. automethod:: to_dict
Creating requests that submit HTML forms
Use :doc:`form2request <form2request:index>` to build request data from an HTML <form> element and convert it to a :class:`~scrapy.Request`.
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Unknown interpreted text role "class".Install it with pip:
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.. code-block:: bash
pip install form2request
Select the desired form with CSS or XPath, then build and convert request data:
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.. code-block:: python
from form2request import form2request
def parse(self, response):
form = response.css("form#search")
request_data = form2request(form, data={"q": "scrapy"})
yield request_data.to_scrapy(callback=self.parse_results)
Use data to override field values. To drop a field from the resulting request, set its value to None.
By default, form2request simulates clicking the first submit button. To submit without clicking any button, pass click=False. To click a specific submit button, pass its element:
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.. code-block:: python
def parse(self, response):
form = response.css("form#checkout")
submit = form.css('button[name="pay"]')
request_data = form2request(form, click=submit)
Using form2request to simulate a user login
It is usual for web sites to provide pre-populated form fields through <input type="hidden"> elements, such as session related data or authentication tokens (for login pages). Build the request from the form and only override the credentials:
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.. code-block:: python
import scrapy
from form2request import form2request
class LoginSpider(scrapy.Spider):
name = "example.com"
start_urls = ["http://www.example.com/users/login.php"]
def parse(self, response):
form = response.css("form")
request_data = form2request(
form,
data={"username": "john", "password": "secret"},
)
yield request_data.to_scrapy(callback=self.after_login)
def after_login(self, response): ...
Passing additional data to callback functions
The callback of a request is a function that will be called when the response of that request is downloaded. The callback function will be called with the downloaded :class:`Response` object as its first argument.
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.. code-block:: python
def parse_page1(self, response):
return scrapy.Request(
"http://www.example.com/some_page.html", callback=self.parse_page2
)
def parse_page2(self, response):
# this would log http://www.example.com/some_page.html
self.logger.info("Visited %s", response.url)
In some cases you may be interested in passing arguments to those callback functions so you can receive the arguments later, in the second callback. The following example shows how to achieve this by using the :attr:`.Request.cb_kwargs` attribute:
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.. code-block:: python
def parse(self, response):
request = scrapy.Request(
"http://www.example.com/index.html",
callback=self.parse_page2,
cb_kwargs=dict(main_url=response.url),
)
request.cb_kwargs["foo"] = "bar" # add more arguments for the callback
yield request
def parse_page2(self, response, main_url, foo):
yield dict(
main_url=main_url,
other_url=response.url,
foo=foo,
)
Caution!
:attr:`.Request.cb_kwargs` was introduced in version 1.7. Prior to that, using :attr:`.Request.meta` was recommended for passing information around callbacks. After 1.7, :attr:`.Request.cb_kwargs` became the preferred way for handling user information, leaving :attr:`.Request.meta` for communication with components like middlewares and extensions.
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Unknown interpreted text role "attr".Using errbacks to catch exceptions in request processing
The errback of a request is a function that will be called when an exception is raise while processing it.
It receives a :exc:`~twisted.python.failure.Failure` as first parameter and can be used to track connection establishment timeouts, DNS errors etc.
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Unknown interpreted text role "exc".Here's an example spider logging all errors and catching some specific errors if needed:
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.. code-block:: python
import scrapy
from scrapy.spidermiddlewares.httperror import HttpError
from twisted.internet.error import DNSLookupError
from twisted.internet.error import TimeoutError, TCPTimedOutError
class ErrbackSpider(scrapy.Spider):
name = "errback_example"
start_urls = [
"http://www.httpbin.org/", # HTTP 200 expected
"http://www.httpbin.org/status/404", # Not found error
"http://www.httpbin.org/status/500", # server issue
"http://www.httpbin.org:12345/", # non-responding host, timeout expected
"https://example.invalid/", # DNS error expected
]
async def start(self):
for u in self.start_urls:
yield scrapy.Request(
u,
callback=self.parse_httpbin,
errback=self.errback_httpbin,
dont_filter=True,
)
def parse_httpbin(self, response):
self.logger.info("Got successful response from {}".format(response.url))
# do something useful here...
def errback_httpbin(self, failure):
# log all failures
self.logger.error(repr(failure))
# in case you want to do something special for some errors,
# you may need the failure's type:
if failure.check(HttpError):
# these exceptions come from HttpError spider middleware
# you can get the non-200 response
response = failure.value.response
self.logger.error("HttpError on %s", response.url)
elif failure.check(DNSLookupError):
# this is the original request
request = failure.request
self.logger.error("DNSLookupError on %s", request.url)
elif failure.check(TimeoutError, TCPTimedOutError):
request = failure.request
self.logger.error("TimeoutError on %s", request.url)
Accessing additional data in errback functions
In case of a failure to process the request, you may be interested in accessing arguments to the callback functions so you can process further based on the arguments in the errback. The following example shows how to achieve this by using Failure.request.cb_kwargs:
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.. code-block:: python
def parse(self, response):
request = scrapy.Request(
"http://www.example.com/index.html",
callback=self.parse_page2,
errback=self.errback_page2,
cb_kwargs=dict(main_url=response.url),
)
yield request
def parse_page2(self, response, main_url):
pass
def errback_page2(self, failure):
yield dict(
main_url=failure.request.cb_kwargs["main_url"],
)
Request fingerprints
There are some aspects of scraping, such as filtering out duplicate requests (see :setting:`DUPEFILTER_CLASS`) or caching responses (see :setting:`HTTPCACHE_POLICY`), where you need the ability to generate a short, unique identifier from a :class:`~scrapy.Request` object: a request fingerprint.
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Unknown interpreted text role "class".You often do not need to worry about request fingerprints, the default request fingerprinter works for most projects.
However, there is no universal way to generate a unique identifier from a request, because different situations require comparing requests differently. For example, sometimes you may need to compare URLs case-insensitively, include URL fragments, exclude certain URL query parameters, include some or all headers, etc.
To change how request fingerprints are built for your requests, use the :setting:`REQUEST_FINGERPRINTER_CLASS` setting.
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.. setting:: REQUEST_FINGERPRINTER_CLASS
REQUEST_FINGERPRINTER_CLASS
Default: :class:`scrapy.utils.request.RequestFingerprinter`
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Unknown interpreted text role "class".A :ref:`request fingerprinter class <custom-request-fingerprinter>` or its import path.
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.. autoclass:: scrapy.utils.request.RequestFingerprinter
Writing your own request fingerprinter
A request fingerprinter is a :ref:`component <topics-components>` that must implement the following method:
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.. currentmodule:: None
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.. method:: fingerprint(self, request: scrapy.Request) Return a :class:`bytes` object that uniquely identifies *request*. See also :ref:`request-fingerprint-restrictions`.
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.. currentmodule:: scrapy.http
The :meth:`fingerprint` method of the default request fingerprinter, :class:`scrapy.utils.request.RequestFingerprinter`, uses :func:`scrapy.utils.request.fingerprint` with its default parameters. For some common use cases you can use :func:`scrapy.utils.request.fingerprint` as well in your :meth:`fingerprint` method implementation:
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.. autofunction:: scrapy.utils.request.fingerprint
By default, request fingerprinting canonicalizes the request URL. If :reqmeta:`verbatim_url` is set to True, fingerprinting does not canonicalize the URL, and the keep_fragments parameter is ignored (it is effectively true).
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Unknown interpreted text role "reqmeta".For example, to take the value of a request header named X-ID into account:
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.. code-block:: python
# my_project/settings.py
REQUEST_FINGERPRINTER_CLASS = "my_project.utils.RequestFingerprinter"
# my_project/utils.py
from scrapy.utils.request import fingerprint
class RequestFingerprinter:
def fingerprint(self, request):
return fingerprint(request, include_headers=["X-ID"])
You can also write your own fingerprinting logic from scratch.
However, if you do not use :func:`scrapy.utils.request.fingerprint`, make sure you use :class:`~weakref.WeakKeyDictionary` to cache request fingerprints:
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Unknown interpreted text role "class".Caching saves CPU by ensuring that fingerprints are calculated only once per request, and not once per Scrapy component that needs the fingerprint of a request.
Using :class:`~weakref.WeakKeyDictionary` saves memory by ensuring that request objects do not stay in memory forever just because you have references to them in your cache dictionary.
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For example, to take into account only the URL of a request, without any prior URL canonicalization or taking the request method or body into account:
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.. code-block:: python
from hashlib import sha1
from weakref import WeakKeyDictionary
from scrapy.utils.python import to_bytes
class RequestFingerprinter:
cache = WeakKeyDictionary()
def fingerprint(self, request):
if request not in self.cache:
fp = sha1()
fp.update(to_bytes(request.url))
self.cache[request] = fp.digest()
return self.cache[request]
If you need to be able to override the request fingerprinting for arbitrary requests from your spider callbacks, you may implement a request fingerprinter that reads fingerprints from :attr:`request.meta <scrapy.Request.meta>` when available, and then falls back to :func:`scrapy.utils.request.fingerprint`. For example:
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.. code-block:: python
from scrapy.utils.request import fingerprint
class RequestFingerprinter:
def fingerprint(self, request):
if "fingerprint" in request.meta:
return request.meta["fingerprint"]
return fingerprint(request)
If you need to reproduce the same fingerprinting algorithm as Scrapy 2.6, use the following request fingerprinter:
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.. code-block:: python
from hashlib import sha1
from weakref import WeakKeyDictionary
from scrapy.utils.python import to_bytes
from w3lib.url import canonicalize_url
class RequestFingerprinter:
cache = WeakKeyDictionary()
def fingerprint(self, request):
if request not in self.cache:
fp = sha1()
fp.update(to_bytes(request.method))
fp.update(to_bytes(canonicalize_url(request.url)))
fp.update(request.body or b"")
self.cache[request] = fp.digest()
return self.cache[request]
Request fingerprint restrictions
Scrapy components that use request fingerprints may impose additional restrictions on the format of the fingerprints that your :ref:`request fingerprinter <custom-request-fingerprinter>` generates.
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Unknown interpreted text role "ref".The following built-in Scrapy components have such restrictions:
:class:`scrapy.extensions.httpcache.FilesystemCacheStorage` (default value of :setting:`HTTPCACHE_STORAGE`)
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Request fingerprints must be at least 1 byte long.
Path and filename length limits of the file system of :setting:`HTTPCACHE_DIR` also apply. Inside :setting:`HTTPCACHE_DIR`, the following directory structure is created:
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-
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- first byte of a request fingerprint as hexadecimal
- fingerprint as hexadecimal
- filenames up to 16 characters long
- fingerprint as hexadecimal
- first byte of a request fingerprint as hexadecimal
For example, if a request fingerprint is made of 20 bytes (default), :setting:`HTTPCACHE_DIR` is '/home/user/project/.scrapy/httpcache', and the name of your spider is 'my_spider' your file system must support a file path like:
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/home/user/project/.scrapy/httpcache/my_spider/01/0123456789abcdef0123456789abcdef01234567/response_headers
-
:class:`scrapy.extensions.httpcache.DbmCacheStorage`
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The underlying DBM implementation must support keys as long as twice the number of bytes of a request fingerprint, plus 5. For example, if a request fingerprint is made of 20 bytes (default), 45-character-long keys must be supported.
Request.meta special keys
The :attr:`.Request.meta` attribute can contain any arbitrary data, but there are some special keys recognized by Scrapy and its built-in extensions.
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-
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:reqmeta:`autothrottle_dont_adjust_delay`
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-
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-
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-
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-
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:reqmeta:`dont_obey_robotstxt`
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-
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-
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:reqmeta:`download_fail_on_dataloss`
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-
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-
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-
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-
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-
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ftp_password (See :setting:`FTP_PASSWORD` for more info)
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ftp_user (See :setting:`FTP_USER` for more info)
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Unknown interpreted text role "setting".
-
System Message: ERROR/3 (<stdin>, line 725); backlink
Unknown interpreted text role "reqmeta".
:reqmeta:`handle_httpstatus_all`
System Message: ERROR/3 (<stdin>, line 726); backlink
Unknown interpreted text role "reqmeta".
:reqmeta:`handle_httpstatus_list`
System Message: ERROR/3 (<stdin>, line 727); backlink
Unknown interpreted text role "reqmeta".
-
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Unknown interpreted text role "reqmeta".
-
System Message: ERROR/3 (<stdin>, line 729); backlink
Unknown interpreted text role "reqmeta".
-
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Unknown interpreted text role "reqmeta".
-
System Message: ERROR/3 (<stdin>, line 731); backlink
Unknown interpreted text role "reqmeta".
-
System Message: ERROR/3 (<stdin>, line 732); backlink
Unknown interpreted text role "reqmeta".
-
System Message: ERROR/3 (<stdin>, line 733); backlink
Unknown interpreted text role "reqmeta".
-
System Message: ERROR/3 (<stdin>, line 734); backlink
Unknown interpreted text role "reqmeta".
-
System Message: ERROR/3 (<stdin>, line 735); backlink
Unknown interpreted text role "reqmeta".
-
System Message: ERROR/3 (<stdin>, line 736); backlink
Unknown interpreted text role "reqmeta".
-
System Message: ERROR/3 (<stdin>, line 737); backlink
Unknown interpreted text role "reqmeta".
System Message: ERROR/3 (<stdin>, line 739)
Unknown directive type "reqmeta".
.. reqmeta:: bindaddress
bindaddress
The default local outgoing address for download-handler connections.
This meta value can be either:
- a host address as a string (e.g. "127.0.0.2"), in which case the local port is chosen automatically, or
- a (host, port) tuple (e.g. ("127.0.0.2", 50000)) to bind to both a specific local interface and a specific local port.
For example:
System Message: WARNING/2 (<stdin>, line 756)
Cannot analyze code. Pygments package not found.
.. code-block:: python
Request(
"https://example.org",
meta={"bindaddress": "127.0.0.2"},
)
System Message: WARNING/2 (<stdin>, line 763)
Cannot analyze code. Pygments package not found.
.. code-block:: python
Request(
"https://example.org",
meta={"bindaddress": ("127.0.0.2", 50000)},
)
If not set, built-in HTTP download handlers use the value of :setting:`DOWNLOAD_BIND_ADDRESS` as the default bind address. Set the :reqmeta:`bindaddress` request meta key to override it for a specific request.
System Message: ERROR/3 (<stdin>, line 770); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 770); backlink
Unknown interpreted text role "reqmeta".This meta key is not supported by :class:`~scrapy.core.downloader.handlers._httpx.HttpxDownloadHandler`, but the :setting:`DOWNLOAD_BIND_ADDRESS` is supported by it.
System Message: ERROR/3 (<stdin>, line 775); backlink
Unknown interpreted text role "class".System Message: ERROR/3 (<stdin>, line 775); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 779)
Unknown directive type "reqmeta".
.. reqmeta:: download_timeout
download_timeout
The amount of time (in secs) that the downloader will wait before timing out. See also: :setting:`DOWNLOAD_TIMEOUT`.
System Message: ERROR/3 (<stdin>, line 784); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 787)
Unknown directive type "reqmeta".
.. reqmeta:: download_latency
download_latency
The amount of time spent to fetch the response, since the request has been started, i.e. HTTP message sent over the network. This meta key only becomes available when the response has been downloaded. While most other meta keys are used to control Scrapy behavior, this one is supposed to be read-only.
System Message: ERROR/3 (<stdin>, line 797)
Unknown directive type "reqmeta".
.. reqmeta:: download_fail_on_dataloss
download_fail_on_dataloss
Whether or not to fail on broken responses. See: :setting:`DOWNLOAD_FAIL_ON_DATALOSS`.
System Message: ERROR/3 (<stdin>, line 802); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 805)
Unknown directive type "reqmeta".
.. reqmeta:: give_up_log_level
give_up_log_level
System Message: ERROR/3 (<stdin>, line 810)
Unknown directive type "versionadded".
.. versionadded:: 2.17.0
:ref:`Logging level <levels>` used for the message logged when a request exceeds its retries. See :setting:`RETRY_GIVE_UP_LOG_LEVEL` for details.
System Message: ERROR/3 (<stdin>, line 812); backlink
Unknown interpreted text role "ref".System Message: ERROR/3 (<stdin>, line 812); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 815)
Unknown directive type "reqmeta".
.. reqmeta:: http_auth_domain
http_auth_domain
System Message: ERROR/3 (<stdin>, line 820)
Unknown directive type "versionadded".
.. versionadded:: 2.17.0
Overrides :setting:`HTTPAUTH_DOMAIN` for this request.
System Message: ERROR/3 (<stdin>, line 822); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 824)
Unknown directive type "reqmeta".
.. reqmeta:: http_pass
http_pass
System Message: ERROR/3 (<stdin>, line 829)
Unknown directive type "versionadded".
.. versionadded:: 2.17.0
Overrides :setting:`HTTPAUTH_PASS` for this request.
System Message: ERROR/3 (<stdin>, line 831); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 833)
Unknown directive type "reqmeta".
.. reqmeta:: http_user
http_user
System Message: ERROR/3 (<stdin>, line 838)
Unknown directive type "versionadded".
.. versionadded:: 2.17.0
Overrides :setting:`HTTPAUTH_USER` for this request.
System Message: ERROR/3 (<stdin>, line 840); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 842)
Unknown directive type "reqmeta".
.. reqmeta:: max_retry_times
max_retry_times
The meta key is used set retry times per request. When set, the :reqmeta:`max_retry_times` meta key takes higher precedence over the :setting:`RETRY_TIMES` setting.
System Message: ERROR/3 (<stdin>, line 847); backlink
Unknown interpreted text role "reqmeta".System Message: ERROR/3 (<stdin>, line 847); backlink
Unknown interpreted text role "setting".System Message: ERROR/3 (<stdin>, line 851)
Unknown directive type "reqmeta".
.. reqmeta:: verbatim_url
verbatim_url
System Message: ERROR/3 (<stdin>, line 856)
Unknown directive type "versionadded".
.. versionadded:: 2.17.0
Set this key to True to keep the request URL as passed to :class:`~scrapy.Request`, without URL percent-encoding.
System Message: ERROR/3 (<stdin>, line 858); backlink
Unknown interpreted text role "class".When this key is enabled, :func:`~scrapy.utils.request.fingerprint` does not canonicalize the request URL, so requests whose URLs differ only in characters that would otherwise be canonicalized get different fingerprints.
System Message: ERROR/3 (<stdin>, line 861); backlink
Unknown interpreted text role "func".In this mode, the keep_fragments parameter is ignored, and it is effectively true.
Stopping the download of a Response
Raising a :exc:`~scrapy.exceptions.StopDownload` exception from a handler for the :class:`~scrapy.signals.bytes_received` or :class:`~scrapy.signals.headers_received` signals will stop the download of a given response. See the following example:
System Message: ERROR/3 (<stdin>, line 873); backlink
Unknown interpreted text role "exc".System Message: ERROR/3 (<stdin>, line 873); backlink
Unknown interpreted text role "class".System Message: ERROR/3 (<stdin>, line 873); backlink
Unknown interpreted text role "class".System Message: WARNING/2 (<stdin>, line 877)
Cannot analyze code. Pygments package not found.
.. code-block:: python
import scrapy
class StopSpider(scrapy.Spider):
name = "stop"
start_urls = ["https://docs.scrapy.org/en/latest/"]
@classmethod
def from_crawler(cls, crawler):
spider = super().from_crawler(crawler)
crawler.signals.connect(
spider.on_bytes_received, signal=scrapy.signals.bytes_received
)
return spider
def parse(self, response):
# 'last_chars' show that the full response was not downloaded
yield {"len": len(response.text), "last_chars": response.text[-40:]}
def on_bytes_received(self, data, request, spider):
raise scrapy.exceptions.StopDownload(fail=False)
which produces the following output:
2020-05-19 17:26:12 [scrapy.core.engine] INFO: Spider opened
2020-05-19 17:26:12 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2020-05-19 17:26:13 [scrapy.core.downloader.handlers.http11] DEBUG: Download stopped for <GET https://docs.scrapy.org/en/latest/> from signal handler StopSpider.on_bytes_received
2020-05-19 17:26:13 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://docs.scrapy.org/en/latest/> (referer: None) ['download_stopped']
2020-05-19 17:26:13 [scrapy.core.scraper] DEBUG: Scraped from <200 https://docs.scrapy.org/en/latest/>
{'len': 279, 'last_chars': 'dth, initial-scale=1.0">\n \n <title>Scr'}
2020-05-19 17:26:13 [scrapy.core.engine] INFO: Closing spider (finished)
By default, resulting responses are handled by their corresponding errbacks. To call their callback instead, like in this example, pass fail=False to the :exc:`~scrapy.exceptions.StopDownload` exception.
System Message: ERROR/3 (<stdin>, line 911); backlink
Unknown interpreted text role "exc".Request subclasses
Here is the list of built-in :class:`~scrapy.Request` subclasses. You can also subclass it to implement your own custom functionality.
System Message: ERROR/3 (<stdin>, line 921); backlink
Unknown interpreted text role "class".FormRequest
System Message: ERROR/3 (<stdin>, line 927)
Unknown directive type "autoclass".
.. autoclass:: scrapy.FormRequest
JsonRequest
The JsonRequest class extends the base :class:`~scrapy.Request` class with functionality for dealing with JSON requests.
System Message: ERROR/3 (<stdin>, line 932); backlink
Unknown interpreted text role "class".System Message: ERROR/3 (<stdin>, line 935)
Invalid class attribute value for "class" directive: "JsonRequest(url, [... data, dumps_kwargs])".
.. class:: JsonRequest(url, [... data, dumps_kwargs])
The :class:`JsonRequest` class adds two new keyword parameters to the ``__init__()`` method. The
remaining arguments are the same as for the :class:`~scrapy.Request` class and are
not documented here.
Using the :class:`JsonRequest` will set the ``Content-Type`` header to ``application/json``
and ``Accept`` header to ``application/json, text/javascript, */*; q=0.01``
:param data: is any JSON serializable object that needs to be JSON encoded and assigned to body.
If the :attr:`~scrapy.Request.body` argument is provided this parameter will be ignored.
If the :attr:`~scrapy.Request.body` argument is not provided and the
``data`` argument is provided the :attr:`~scrapy.Request.method` will be
set to ``'POST'`` automatically.
:type data: object
:param dumps_kwargs: Parameters that will be passed to underlying :func:`json.dumps` method which is used to serialize
data into JSON format.
:type dumps_kwargs: dict
.. autoattribute:: JsonRequest.attributes
JsonRequest usage example
Sending a JSON POST request with a JSON payload:
System Message: WARNING/2 (<stdin>, line 963)
Cannot analyze code. Pygments package not found.
.. code-block:: python
data = {
"name1": "value1",
"name2": "value2",
}
yield JsonRequest(url="http://www.example.com/post/action", data=data)
Response objects
System Message: ERROR/3 (<stdin>, line 975)
Unknown directive type "autoclass".
.. autoclass:: Response
:param url: the URL of this response
:type url: str
:param status: the HTTP status of the response. Defaults to ``200``.
:type status: int
:param headers: the headers of this response. The dict values can be strings
(for single valued headers) or lists (for multi-valued headers).
:type headers: dict
:param body: the response body. To access the decoded text as a string, use
``response.text`` from an encoding-aware
:ref:`Response subclass <topics-request-response-ref-response-subclasses>`,
such as :class:`TextResponse`.
:type body: bytes
:param flags: is a list containing the initial values for the
:attr:`Response.flags` attribute. If given, the list will be shallow
copied.
:type flags: list
:param request: the initial value of the :attr:`Response.request` attribute.
This represents the :class:`~scrapy.Request` that generated this response.
:type request: scrapy.Request
:param certificate: an object representing the server's SSL certificate.
:type certificate: typing.Any
:param ip_address: The IP address of the server from which the Response originated.
:type ip_address: :class:`ipaddress.IPv4Address` or :class:`ipaddress.IPv6Address`
:param protocol: The protocol that was used to download the response.
For instance: "HTTP/1.0", "HTTP/1.1", "h2"
:type protocol: :class:`str`
.. attribute:: Response.url
A string containing the URL of the response.
This attribute is read-only. To change the URL of a Response use
:meth:`replace`.
.. attribute:: Response.status
An integer representing the HTTP status of the response. Example: ``200``,
``404``.
.. attribute:: Response.headers
A dictionary-like (:class:`scrapy.http.headers.Headers`) object which contains
the response headers. Values can be accessed using
:meth:`~scrapy.http.headers.Headers.get` to return the last header value with
the specified name or :meth:`~scrapy.http.headers.Headers.getlist` to return
all header values with the specified name. For example, this call will give you
all cookies in the headers::
response.headers.getlist('Set-Cookie')
.. attribute:: Response.body
The response body as bytes.
If you want the body as a string, use :attr:`TextResponse.text` (only
available in :class:`TextResponse` and subclasses).
This attribute is read-only. To change the body of a Response use
:meth:`replace`.
.. attribute:: Response.request
The :class:`~scrapy.Request` object that generated this response. This attribute is
assigned in the Scrapy engine, after the response and the request have passed
through all :ref:`Downloader Middlewares <topics-downloader-middleware>`.
In particular, this means that:
- HTTP redirections will create a new request from the request before
redirection. It has the majority of the same metadata and original
request attributes and gets assigned to the redirected response
instead of the propagation of the original request.
- Response.request.url doesn't always equal Response.url
- This attribute is only available in the spider code, and in the
:ref:`Spider Middlewares <topics-spider-middleware>`, but not in
Downloader Middlewares (although you have the Request available there by
other means) and handlers of the :signal:`response_downloaded` signal.
.. attribute:: Response.meta
A shortcut to the :attr:`~scrapy.Request.meta` attribute of the
:attr:`Response.request` object (i.e. ``self.request.meta``).
Unlike the :attr:`Response.request` attribute, the :attr:`Response.meta`
attribute is propagated along redirects and retries, so you will get
the original :attr:`.Request.meta` sent from your spider.
.. seealso:: :attr:`.Request.meta` attribute
.. attribute:: Response.cb_kwargs
A shortcut to the :attr:`~scrapy.Request.cb_kwargs` attribute of the
:attr:`Response.request` object (i.e. ``self.request.cb_kwargs``).
Unlike the :attr:`Response.request` attribute, the
:attr:`Response.cb_kwargs` attribute is propagated along redirects and
retries, so you will get the original :attr:`.Request.cb_kwargs` sent from your spider.
.. seealso:: :attr:`.Request.cb_kwargs` attribute
.. attribute:: Response.flags
A list that contains flags for this response. Flags are labels used for
tagging Responses. For example: ``'cached'``, ``'redirected'``', etc. And
they're shown on the string representation of the Response (``__str__()``
method) which is used by the engine for logging.
.. attribute:: Response.certificate
An object representing the server's SSL certificate. Its type and
contents depend on the download handler that produced the response.
Only populated for ``https`` responses, ``None`` otherwise.
.. attribute:: Response.ip_address
The IP address of the server from which the Response originated.
This attribute is currently only populated by the HTTP download
handlers, i.e. for ``http(s)`` responses. For other handlers,
:attr:`ip_address` is always ``None``.
.. attribute:: Response.protocol
The protocol that was used to download the response.
For instance: "HTTP/1.0", "HTTP/1.1"
This attribute is currently only populated by the HTTP download
handlers, i.e. for ``http(s)`` responses. For other handlers,
:attr:`protocol` is always ``None``.
.. autoattribute:: Response.attributes
.. method:: Response.copy()
Returns a new Response which is a copy of this Response.
.. method:: Response.replace([url, status, headers, body, request, flags, certificate, ip_address, protocol, cls])
Returns a Response object with the same members, except for those members
given new values by whichever keyword arguments are specified. The
attribute :attr:`Response.meta` is copied by default.
.. method:: Response.urljoin(url)
Constructs an absolute url by combining the Response's :attr:`url` with
a possible relative url.
This is a wrapper over :func:`~urllib.parse.urljoin`, it's merely an alias for
making this call::
urllib.parse.urljoin(response.url, url)
.. automethod:: Response.follow
.. automethod:: Response.follow_all
Response subclasses
Here is the list of available built-in Response subclasses. You can also subclass the Response class to implement your own functionality.
TextResponse objects
System Message: ERROR/3 (<stdin>, line 1155)
Invalid class attribute value for "class" directive: "TextResponse(url, [encoding[, ...]])".
.. class:: TextResponse(url, [encoding[, ...]])
:class:`TextResponse` objects adds encoding capabilities to the base
:class:`Response` class, which is meant to be used only for binary data,
such as images, sounds or any media file.
:class:`TextResponse` objects support a new ``__init__()`` method argument, in
addition to the base :class:`Response` objects. The remaining functionality
is the same as for the :class:`Response` class and is not documented here.
:param encoding: is a string which contains the encoding to use for this
response. If you create a :class:`TextResponse` object with a string as
body, it will be converted to bytes encoded using this encoding. If
*encoding* is ``None`` (default), the encoding will be looked up in the
response headers and body instead.
:type encoding: str
:class:`TextResponse` objects support the following attributes in addition
to the standard :class:`Response` ones:
.. attribute:: TextResponse.text
Response body, as a string.
The same as ``response.body.decode(response.encoding)``, but the
result is cached after the first call, so you can access
``response.text`` multiple times without extra overhead.
.. note::
``str(response.body)`` is not a correct way to convert the response
body into a string:
.. code-block:: pycon
>>> str(b"body")
"b'body'"
.. attribute:: TextResponse.encoding
A string with the encoding of this response. The encoding is resolved by
trying the following mechanisms, in order:
1. the encoding passed in the ``__init__()`` method ``encoding`` argument
2. the encoding declared in the Content-Type HTTP header. If this
encoding is not valid (i.e. unknown), it is ignored and the next
resolution mechanism is tried.
3. the encoding declared in the response body. The TextResponse class
doesn't provide any special functionality for this. However, the
:class:`HtmlResponse` and :class:`XmlResponse` classes do.
4. the encoding inferred by looking at the response body. This is the more
fragile method but also the last one tried.
.. attribute:: TextResponse.selector
A :class:`~scrapy.Selector` instance using the response as
target. The selector is lazily instantiated on first access.
.. autoattribute:: TextResponse.attributes
:class:`TextResponse` objects support the following methods in addition to
the standard :class:`Response` ones:
.. method:: TextResponse.jmespath(query)
A shortcut to ``TextResponse.selector.jmespath(query)``::
response.jmespath('object.[*]')
.. method:: TextResponse.xpath(query)
A shortcut to ``TextResponse.selector.xpath(query)``::
response.xpath('//p')
.. method:: TextResponse.css(query)
A shortcut to ``TextResponse.selector.css(query)``::
response.css('p')
.. automethod:: TextResponse.follow
.. automethod:: TextResponse.follow_all
.. automethod:: TextResponse.json()
Returns a Python object from deserialized JSON document.
The result is cached after the first call.
.. method:: TextResponse.urljoin(url)
Constructs an absolute url by combining the Response's base url with
a possible relative url. The base url shall be extracted from the
``<base>`` tag, or just :attr:`Response.url` if there is no such
tag.
HtmlResponse objects
System Message: ERROR/3 (<stdin>, line 1261)
Invalid class attribute value for "class" directive: "HtmlResponse(url[, ...])".
.. class:: HtmlResponse(url[, ...])
The :class:`HtmlResponse` class is a subclass of :class:`TextResponse`
which adds encoding auto-discovering support by looking into the HTML `meta
http-equiv`_ attribute. See :attr:`TextResponse.encoding`.
XmlResponse objects
System Message: ERROR/3 (<stdin>, line 1272)
Invalid class attribute value for "class" directive: "XmlResponse(url[, ...])".
.. class:: XmlResponse(url[, ...])
The :class:`XmlResponse` class is a subclass of :class:`TextResponse` which
adds encoding auto-discovering support by looking into the XML declaration
line. See :attr:`TextResponse.encoding`.
JsonResponse objects
System Message: ERROR/3 (<stdin>, line 1283)
Invalid class attribute value for "class" directive: "JsonResponse(url[, ...])".
.. class:: JsonResponse(url[, ...])
The :class:`JsonResponse` class is a subclass of :class:`TextResponse`
that is used when the response has a `JSON MIME type
<https://mimesniff.spec.whatwg.org/#json-mime-type>`_ in its `Content-Type`
header.