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docs/topics/request-response.rst
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Adrian
Add a cookies documentation page (#7947)
09 авг 2026, 20:41
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.. _topics-request-response: ====================== Requests and Responses ====================== .. module:: scrapy.http :synopsis: Request and Response classes Scrapy uses :class:`~scrapy.Request` and :class:`Response` objects for crawling web sites. 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. 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`. Request objects =============== .. 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:`cookie middleware <cookies>`. If you need to set cookies for a request, use the ``cookies`` argument. :type headers: dict :param cookies: the request cookies, as a dict of cookie names and values or as a list of dicts with a cookie each. See :ref:`cookies`. :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 your own data from one spider callback to another, use :attr:`cb_kwargs` instead, see :ref:`callback-data`. 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. .. seealso:: :class:`~scrapy.spidermiddlewares.metacopy.MetaCopyDetectionMiddleware` for a built-in middleware that warns about this issue at run time. .. autoattribute:: dont_filter .. autoattribute:: Request.attributes .. method:: Request.copy() Return a new Request which is a copy of this Request. See also: :ref:`callback-data`. .. 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:`callback-data`. .. automethod:: from_curl .. automethod:: to_curl .. automethod:: to_dict .. _form: 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`. Install it with pip: .. code-block:: bash pip install form2request Select the desired form with CSS or XPath, then build and convert request data: .. 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: .. code-block:: python def parse(self, response): form = response.css("form#checkout") submit = form.css('button[name="pay"]') request_data = form2request(form, click=submit) .. _topics-request-response-ref-request-userlogin: 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: .. 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): ... Other functions related to requests ----------------------------------- .. autofunction:: scrapy.http.request.NO_CALLBACK .. autofunction:: scrapy.utils.request.request_from_dict .. autofunction:: scrapy.utils.httpobj.urlparse_cached .. _request-fingerprints: 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. 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. .. setting:: REQUEST_FINGERPRINTER_CLASS REQUEST_FINGERPRINTER_CLASS ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Default: :class:`scrapy.utils.request.RequestFingerprinter` A :ref:`request fingerprinter class <custom-request-fingerprinter>` or its import path. .. autoclass:: scrapy.utils.request.RequestFingerprinter .. _custom-request-fingerprinter: Writing your own request fingerprinter ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A request fingerprinter is a :ref:`component <topics-components>` that must implement the following method: .. currentmodule:: None .. method:: fingerprint(self, request: scrapy.Request) Return a :class:`bytes` object that uniquely identifies *request*. See also :ref:`request-fingerprint-restrictions`. .. 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: .. 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). For example, to take the value of a request header named ``X-ID`` into account: .. 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: - 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. 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: .. 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: .. 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: .. 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: 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. The following built-in Scrapy components have such restrictions: - :class:`scrapy.extensions.httpcache.FilesystemCacheStorage` (default value of :setting:`HTTPCACHE_STORAGE`) 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: - :attr:`.Spider.name` - first byte of a request fingerprint as hexadecimal - fingerprint as hexadecimal - filenames up to 16 characters long 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:: /home/user/project/.scrapy/httpcache/my_spider/01/0123456789abcdef0123456789abcdef01234567/response_headers - :class:`scrapy.extensions.httpcache.DbmCacheStorage` 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. .. _callbacks: Callbacks ========= A callback is a function that Scrapy calls with the :class:`Response` of a :class:`~scrapy.Request` once that request has been downloaded, so that you can extract data from that response and generate additional requests to continue the crawl: .. code-block:: python from scrapy import Request, Spider class BookSpider(Spider): name = "books" async def start(self): yield Request("https://books.toscrape.com/", callback=self.parse_home) def parse_home(self, response): for url in response.css("h3 a::attr(href)").getall(): yield Request(response.urljoin(url), callback=self.parse_book) def parse_book(self, response): yield {"title": response.css("h1::text").get()} Requests may also define an :ref:`errback <errbacks>`, which Scrapy calls instead of the callback when an exception is raised while processing the request or its response, e.g. a connection error or, by default, a non-2xx response. .. _callback-assignment: Assigning a callback to a request --------------------------------- To assign a callback to a request, use the ``callback`` parameter of :class:`~scrapy.Request`, which sets the :attr:`.Request.callback` attribute: .. code-block:: python from scrapy import Request def parse_home(response): ... request = Request("https://books.toscrape.com/", callback=parse_home) Requests with no callback, i.e. with :attr:`~scrapy.Request.callback` set to ``None``, are handled by the :meth:`~scrapy.Spider.parse` method of the spider: .. code-block:: python request = Request("https://books.toscrape.com/") # Handled by parse() If a request is never meant to reach a spider callback, e.g. because a :ref:`component <topics-components>` sends it and handles its response itself, assign the special :func:`~scrapy.http.request.NO_CALLBACK` value to it instead, so that :ref:`downloader middlewares <topics-downloader-middleware>` can tell such requests apart. While :attr:`~scrapy.Request.callback` only accepts callables, some spider classes let you also define a callback by name: both :attr:`CrawlSpider.rules <scrapy.spiders.CrawlSpider.rules>` and :attr:`SitemapSpider.sitemap_rules <scrapy.spiders.SitemapSpider.sitemap_rules>` accept the name of a spider method as a string. .. _writing-callbacks: Writing a callback ------------------ Any callable can be a callback, as long as it takes the response as its first positional parameter, and any :ref:`additional callback data <callback-data>` as keyword parameters. Spider methods are the most common choice, but plain functions, lambda expressions and other callable objects work as well. .. note:: If you enable :ref:`job persistence <topics-jobs>` through the :setting:`JOBDIR` setting, callbacks must be methods of the running spider. Requests with any other callback cannot be serialized, so they are kept in memory only and lost when you pause the crawl. See :ref:`request-serialization`. A callback can be: - A regular function: .. code-block:: python def parse(self, response): return {"url": response.url} - A generator function: .. code-block:: python def parse(self, response): yield {"url": response.url} - A coroutine function, i.e. defined with ``async def``: .. code-block:: python async def parse(self, response): return {"url": response.url} - An asynchronous generator function: .. code-block:: python async def parse(self, response): yield {"url": response.url} The last two allow using ``await``, ``async for`` and ``async with`` in your callback. See :ref:`topics-coroutines`. .. _callback-output: Callback output --------------- A callback may return or yield any of the following: - ``None``, which does nothing. Callbacks that produce no output at all, e.g. callbacks that only log information about the response, are perfectly valid. ``None`` values within an iterable of callback output are ignored as well. - A :class:`~scrapy.Request` object, which Scrapy schedules, downloads and eventually sends to its own callback. - An :ref:`item object <topics-items>`, which Scrapy sends to the :ref:`item pipelines <topics-item-pipeline>`. Any object that is neither ``None`` nor a :class:`~scrapy.Request` object is treated as an item. - An iterable of any of the values above, e.g. a list or, more commonly, a generator. :term:`Asynchronous iterables <asynchronous iterable>`, e.g. an :term:`asynchronous generator`, are also supported. .. note:: When a callback *returns* an object, Scrapy iterates that object if it supports iteration, except for :class:`dict`, :class:`~scrapy.Item`, :class:`str` and :class:`bytes` objects, which are always handled as single items. .. note:: In a generator callback, a ``return`` statement with a value does not produce any output, since such a value is not part of what the generator yields. Scrapy logs a warning when it detects such a callback, see :setting:`WARN_ON_GENERATOR_RETURN_VALUE`. Before Scrapy acts on the output of a callback, that output goes through the :meth:`~scrapy.spidermiddlewares.SpiderMiddleware.process_spider_output` method of your :ref:`spider middlewares <topics-spider-middleware>`, which may modify it or drop part of it. If a callback raises an exception, the :attr:`~scrapy.Request.errback` of the request is *not* called. The exception goes through the :meth:`~scrapy.spidermiddlewares.SpiderMiddleware.process_spider_exception` method of your spider middlewares instead and, unless one of them handles it, Scrapy logs it and sends the :signal:`spider_error` signal. .. _callback-data: .. _topics-request-response-ref-request-callback-arguments: Passing additional data to callback functions --------------------------------------------- In some cases you may be interested in passing data to a callback in addition to the response, e.g. data extracted from the response that triggered the request. The following example shows how to achieve this by using the :attr:`.Request.cb_kwargs` attribute: .. code-block:: python from scrapy import Request def parse(self, response): request = 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, ) :attr:`.Request.cb_kwargs` is the recommended way to pass your own data to a callback. Use :attr:`.Request.meta` only for data aimed at :ref:`components <topics-components>`, such as middlewares and extensions. .. _errbacks: .. _topics-request-response-ref-errbacks: Errbacks ======== 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. If an errback raises an exception, Scrapy logs it and sends the :signal:`spider_error` signal, unless the exception is the one that the errback received, which Scrapy logs as a download error instead. Here's an example spider logging all errors and catching some specific errors if needed: .. code-block:: python from scrapy import Request, Spider from scrapy.spidermiddlewares.httperror import HttpError from twisted.internet.error import DNSLookupError from twisted.internet.error import TimeoutError, TCPTimedOutError class ErrbackSpider(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 Request( u, callback=self.parse_httpbin, errback=self.errback_httpbin, dont_filter=True, ) def parse_httpbin(self, response): self.logger.info(f"Got successful response from {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) .. _errback-cb_kwargs: 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``: .. code-block:: python from scrapy import Request def parse(self, response): request = 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"], ) .. _topics-request-meta: 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. Those are: * :reqmeta:`allow_offsite` * :reqmeta:`autothrottle_dont_adjust_delay` * :reqmeta:`bindaddress` * :reqmeta:`cookiejar` * :reqmeta:`dont_cache` * :reqmeta:`dont_merge_cookies` * :reqmeta:`dont_obey_robotstxt` * :reqmeta:`dont_redirect` * :reqmeta:`dont_retry` * :reqmeta:`download_fail_on_dataloss` * :reqmeta:`download_latency` * :reqmeta:`download_maxsize` * :reqmeta:`download_slot` * :reqmeta:`download_warnsize` * :reqmeta:`download_timeout` * ``ftp_password`` (See :setting:`FTP_PASSWORD` for more info) * ``ftp_user`` (See :setting:`FTP_USER` for more info) * :reqmeta:`give_up_log_level` * :reqmeta:`handle_httpstatus_all` * :reqmeta:`handle_httpstatus_list` * :reqmeta:`http_auth_domain` * :reqmeta:`http_pass` * :reqmeta:`http_user` * :reqmeta:`is_start_request` * :reqmeta:`max_retry_times` * :reqmeta:`proxy` * :reqmeta:`redirect_reasons` * :reqmeta:`redirect_urls` * :reqmeta:`referrer_policy` * :reqmeta:`verbatim_url` .. 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: .. code-block:: python Request( "https://example.org", meta={"bindaddress": "127.0.0.2"}, ) .. 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. This meta key is not supported by :class:`~scrapy.core.downloader.handlers._httpx.HttpxDownloadHandler`, but the :setting:`DOWNLOAD_BIND_ADDRESS` is supported by it. .. reqmeta:: download_timeout download_timeout ---------------- The amount of time (in secs) that the downloader will wait before timing out. See also: :setting:`DOWNLOAD_TIMEOUT`. .. 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. .. reqmeta:: download_fail_on_dataloss download_fail_on_dataloss ------------------------- Whether or not to fail on broken responses. See: :setting:`DOWNLOAD_FAIL_ON_DATALOSS`. .. reqmeta:: give_up_log_level give_up_log_level ----------------- .. 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. .. reqmeta:: http_auth_domain http_auth_domain ---------------- .. versionadded:: 2.17.0 Overrides :setting:`HTTPAUTH_DOMAIN` for this request. .. reqmeta:: http_pass http_pass --------- .. versionadded:: 2.17.0 Overrides :setting:`HTTPAUTH_PASS` for this request. .. reqmeta:: http_user http_user --------- .. versionadded:: 2.17.0 Overrides :setting:`HTTPAUTH_USER` for this request. .. 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. .. reqmeta:: verbatim_url verbatim_url ------------ .. versionadded:: 2.17.0 Set this key to ``True`` to keep the request URL as passed to :class:`~scrapy.Request`, without URL percent-encoding. 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. In this mode, the ``keep_fragments`` parameter is ignored, and it is effectively true. .. _topics-stop-response-download: 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: .. 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. .. _topics-request-response-ref-request-subclasses: Request subclasses ================== Here is the list of built-in :class:`~scrapy.Request` subclasses. You can also subclass it to implement your own custom functionality. FormRequest ----------- .. autoclass:: scrapy.FormRequest JsonRequest ----------- The JsonRequest class extends the base :class:`~scrapy.Request` class with functionality for dealing with JSON requests. .. 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: .. skip: next .. code-block:: python data = { "name1": "value1", "name2": "value2", } yield JsonRequest(url="http://www.example.com/post/action", data=data) Response objects ================ .. 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: .. skip: next .. code-block:: python 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: .. skip: next .. code-block:: python urllib.parse.urljoin(response.url, url) .. automethod:: Response.follow .. automethod:: Response.follow_all .. _topics-request-response-ref-response-subclasses: 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 -------------------- .. 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) .. skip: start A shortcut to ``TextResponse.selector.jmespath(query)``: .. code-block:: python response.jmespath("object.[*]") .. method:: TextResponse.xpath(query) A shortcut to ``TextResponse.selector.xpath(query)``: .. code-block:: python response.xpath("//p") .. method:: TextResponse.css(query) A shortcut to ``TextResponse.selector.css(query)``: .. code-block:: python response.css("p") .. skip: end .. automethod:: TextResponse.follow .. automethod:: TextResponse.follow_all .. automethod:: TextResponse.json() .. 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 -------------------- .. 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`. .. _meta http-equiv: https://www.w3schools.com/TAGS/att_meta_http_equiv.asp XmlResponse objects ------------------- .. 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`. .. _bug in lxml: https://bugs.launchpad.net/lxml/+bug/1665241 JsonResponse objects -------------------- .. 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.