RomanNum3ral
/
scrapy
mirror of https://github.com/scrapy/scrapy.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
scrapy/docs/topics/downloader-middleware.rst

24 KiB
Raw Blame History

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> </head>

Downloader Middleware

The downloader middleware is a framework of hooks into Scrapy's request/response processing. It's a light, low-level system for globally altering Scrapy's requests and responses.

Activating a downloader middleware

To activate a downloader middleware component, add it to the :setting:`DOWNLOADER_MIDDLEWARES` setting, which is a dict whose keys are the middleware class paths and their values are the middleware orders.

System Message: ERROR/3 (<stdin>, line 16); backlink

Unknown interpreted text role "setting".

Here's an example:

DOWNLOADER_MIDDLEWARES = {
    'myproject.middlewares.CustomDownloaderMiddleware': 543,
}

The :setting:`DOWNLOADER_MIDDLEWARES` setting is merged with the :setting:`DOWNLOADER_MIDDLEWARES_BASE` setting defined in Scrapy (and not meant to be overridden) and then sorted by order to get the final sorted list of enabled middlewares: the first middleware is the one closer to the engine and the last is the one closer to the downloader.

System Message: ERROR/3 (<stdin>, line 26); backlink

Unknown interpreted text role "setting".

System Message: ERROR/3 (<stdin>, line 26); backlink

Unknown interpreted text role "setting".

To decide which order to assign to your middleware see the :setting:`DOWNLOADER_MIDDLEWARES_BASE` setting and pick a value according to where you want to insert the middleware. The order does matter because each middleware performs a different action and your middleware could depend on some previous (or subsequent) middleware being applied.

System Message: ERROR/3 (<stdin>, line 32); backlink

Unknown interpreted text role "setting".

If you want to disable a built-in middleware (the ones defined in :setting:`DOWNLOADER_MIDDLEWARES_BASE` and enabled by default) you must define it in your project's :setting:`DOWNLOADER_MIDDLEWARES` setting and assign None as its value. For example, if you want to disable the off-site middleware:

System Message: ERROR/3 (<stdin>, line 38); backlink

Unknown interpreted text role "setting".

System Message: ERROR/3 (<stdin>, line 38); backlink

Unknown interpreted text role "setting".
DOWNLOADER_MIDDLEWARES = {
    'myproject.middlewares.CustomDownloaderMiddleware': 543,
    'scrapy.contrib.downloadermiddleware.useragent.UserAgentMiddleware': None,
}

Finally, keep in mind that some middlewares may need to be enabled through a particular setting. See each middleware documentation for more info.

Writing your own downloader middleware

Writing your own downloader middleware is easy. Each middleware component is a single Python class that defines one or more of the following methods:

System Message: ERROR/3 (<stdin>, line 57)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware

System Message: ERROR/3 (<stdin>, line 61)

Unknown directive type "method".

.. method:: process_request(request, spider)

   This method is called for each request that goes through the download
   middleware.

   :meth:`process_request` should return either ``None``, a
   :class:`~scrapy.http.Response` object, or a :class:`~scrapy.http.Request`
   object.

   If it returns ``None``, Scrapy will continue processing this request, executing all
   other middlewares until, finally, the appropriate downloader handler is called
   the request performed (and its response downloaded).

   If it returns a :class:`~scrapy.http.Response` object, Scrapy won't bother
   calling ANY other request or exception middleware, or the appropriate
   download function; it'll return that Response. Response middleware is
   always called on every Response.

   If it returns a :class:`~scrapy.http.Request` object, the returned request will be
   rescheduled (in the Scheduler) to be downloaded in the future. The callback of
   the original request will always be called. If the new request has a callback
   it will be called with the response downloaded, and the output of that callback
   will then be passed to the original callback. If the new request doesn't have a
   callback, the response downloaded will be just passed to the original request
   callback.

   If it returns an :exc:`~scrapy.exceptions.IgnoreRequest` exception, the
   entire request will be dropped completely and its callback never called.

   :param request: the request being processed
   :type request: :class:`~scrapy.http.Request` object

   :param spider: the spider for which this request is intended
   :type spider: :class:`~scrapy.spider.BaseSpider` object

System Message: ERROR/3 (<stdin>, line 96)

Unknown directive type "method".

.. method:: process_response(request, response, spider)

   :meth:`process_response` should return a :class:`~scrapy.http.Response`
   object or raise a :exc:`~scrapy.exceptions.IgnoreRequest` exception.

   If it returns a :class:`~scrapy.http.Response` (it could be the same given
   response, or a brand-new one), that response will continue to be processed
   with the :meth:`process_response` of the next middleware in the pipeline.

   If it returns an :exc:`~scrapy.exceptions.IgnoreRequest` exception, the
   response will be dropped completely and its callback never called.

   :param request: the request that originated the response
   :type request: is a :class:`~scrapy.http.Request` object

   :param response: the response being processed
   :type response: :class:`~scrapy.http.Response` object

   :param spider: the spider for which this response is intended
   :type spider: :class:`~scrapy.spider.BaseSpider` object

System Message: ERROR/3 (<stdin>, line 117)

Unknown directive type "method".

.. method:: process_exception(request, exception, spider)

   Scrapy calls :meth:`process_exception` when a download handler
   or a :meth:`process_request` (from a downloader middleware) raises an
   exception.

   :meth:`process_exception` should return either ``None``,
   :class:`~scrapy.http.Response` or :class:`~scrapy.http.Request` object.

   If it returns ``None``, Scrapy will continue processing this exception,
   executing any other exception middleware, until no middleware is left and
   the default exception handling kicks in.

   If it returns a :class:`~scrapy.http.Response` object, the response middleware
   kicks in, and won't bother calling any other exception middleware.

   If it returns a :class:`~scrapy.http.Request` object, the returned request is
   used to instruct an immediate redirection.
   The original request won't finish until the redirected
   request is completed. This stops the :meth:`process_exception`
   middleware the same as returning Response would do.

   :param request: the request that generated the exception
   :type request: is a :class:`~scrapy.http.Request` object

   :param exception: the raised exception
   :type exception: an ``Exception`` object

   :param spider: the spider for which this request is intended
   :type spider: :class:`~scrapy.spider.BaseSpider` object

Built-in downloader middleware reference

This page describes all downloader middleware components that come with Scrapy. For information on how to use them and how to write your own downloader middleware, see the :ref:`downloader middleware usage guide <topics-downloader-middleware>`.

System Message: ERROR/3 (<stdin>, line 153); backlink

Unknown interpreted text role "ref".

For a list of the components enabled by default (and their orders) see the :setting:`DOWNLOADER_MIDDLEWARES_BASE` setting.

System Message: ERROR/3 (<stdin>, line 158); backlink

Unknown interpreted text role "setting".

CookiesMiddleware

System Message: ERROR/3 (<stdin>, line 166)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.cookies
   :synopsis: Cookies Downloader Middleware

This middleware enables working with sites that require cookies, such as those that use sessions. It keeps track of cookies sent by web servers, and send them back on subsequent requests (from that spider), just like web browsers do.

The following settings can be used to configure the cookie middleware:

System Message: ERROR/3 (<stdin>, line 181)

Unknown directive type "reqmeta".

.. reqmeta:: cookiejar

Multiple cookie sessions per spider

System Message: ERROR/3 (<stdin>, line 186)

Unknown directive type "versionadded".

.. versionadded:: 0.15

There is support for keeping multiple cookie sessions per spider by using the :reqmeta:`cookiejar` Request meta key. By default it uses a single cookie jar (session), but you can pass an identifier to use different ones.

System Message: ERROR/3 (<stdin>, line 188); backlink

Unknown interpreted text role "reqmeta".

For example:

for i, url in enumerate(urls):
    yield Request("http://www.example.com", meta={'cookiejar': i},
        callback=self.parse_page)

Keep in mind that the :reqmeta:`cookiejar` meta key is not "sticky". You need to keep passing it along on subsequent requests. For example:

System Message: ERROR/3 (<stdin>, line 198); backlink

Unknown interpreted text role "reqmeta".
def parse_page(self, response):
    # do some processing
    return Request("http://www.example.com/otherpage",
        meta={'cookiejar': response.meta['cookiejar']},
        callback=self.parse_other_page)

System Message: ERROR/3 (<stdin>, line 207)

Unknown directive type "setting".

.. setting:: COOKIES_ENABLED

COOKIES_ENABLED

Default: True

Whether to enable the cookies middleware. If disabled, no cookies will be sent to web servers.

System Message: ERROR/3 (<stdin>, line 217)

Unknown directive type "setting".

.. setting:: COOKIES_DEBUG

COOKIES_DEBUG

Default: False

If enabled, Scrapy will log all cookies sent in requests (ie. Cookie header) and all cookies received in responses (ie. Set-Cookie header).

Here's an example of a log with :setting:`COOKIES_DEBUG` enabled:

System Message: ERROR/3 (<stdin>, line 227); backlink

Unknown interpreted text role "setting".
2011-04-06 14:35:10-0300 [diningcity] INFO: Spider opened
2011-04-06 14:35:10-0300 [diningcity] DEBUG: Sending cookies to: <GET http://www.diningcity.com/netherlands/index.html>
        Cookie: clientlanguage_nl=en_EN
2011-04-06 14:35:14-0300 [diningcity] DEBUG: Received cookies from: <200 http://www.diningcity.com/netherlands/index.html>
        Set-Cookie: JSESSIONID=B~FA4DC0C496C8762AE4F1A620EAB34F38; Path=/
        Set-Cookie: ip_isocode=US
        Set-Cookie: clientlanguage_nl=en_EN; Expires=Thu, 07-Apr-2011 21:21:34 GMT; Path=/
2011-04-06 14:49:50-0300 [diningcity] DEBUG: Crawled (200) <GET http://www.diningcity.com/netherlands/index.html> (referer: None)
[...]

DefaultHeadersMiddleware

System Message: ERROR/3 (<stdin>, line 243)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.defaultheaders
   :synopsis: Default Headers Downloader Middleware

This middleware sets all default requests headers specified in the :setting:`DEFAULT_REQUEST_HEADERS` setting.

System Message: ERROR/3 (<stdin>, line 248); backlink

Unknown interpreted text role "setting".

DownloadTimeoutMiddleware

System Message: ERROR/3 (<stdin>, line 254)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.downloadtimeout
   :synopsis: Download timeout middleware

This middleware sets the download timeout for requests specified in the :setting:`DOWNLOAD_TIMEOUT` setting.

System Message: ERROR/3 (<stdin>, line 259); backlink

Unknown interpreted text role "setting".

HttpAuthMiddleware

System Message: ERROR/3 (<stdin>, line 265)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.httpauth
   :synopsis: HTTP Auth downloader middleware

This middleware authenticates all requests generated from certain spiders using Basic access authentication (aka. HTTP auth).

To enable HTTP authentication from certain spiders, set the http_user and http_pass attributes of those spiders.

Example:

class SomeIntranetSiteSpider(CrawlSpider):

    http_user = 'someuser'
    http_pass = 'somepass'
    name = 'intranet.example.com'

    # .. rest of the spider code omitted ...

HttpCacheMiddleware

System Message: ERROR/3 (<stdin>, line 292)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.httpcache
   :synopsis: HTTP Cache downloader middleware

This middleware provides low-level cache to all HTTP requests and responses. It has to be combined with a cache storage backend as well as a cache policy.

Scrapy ships with two HTTP cache storage backends:

You can change the HTTP cache storage backend with the :setting:`HTTPCACHE_STORAGE` setting. Or you can also implement your own storage backend.

System Message: ERROR/3 (<stdin>, line 305); backlink

Unknown interpreted text role "setting".

Scrapy ships with two HTTP cache policies:

You can change the HTTP cache policy with the :setting:`HTTPCACHE_POLICY` setting. Or you can also implement your own policy.

System Message: ERROR/3 (<stdin>, line 313); backlink

Unknown interpreted text role "setting".

Dummy policy (default)

This policy has no awareness of any HTTP Cache-Control directives. Every request and its corresponding response are cached. When the same request is seen again, the response is returned without transferring anything from the Internet.

The Dummy policy is useful for testing spiders faster (without having to wait for downloads every time) and for trying your spider offline, when an Internet connection is not available. The goal is to be able to "replay" a spider run exactly as it ran before.

In order to use this policy, set:

RFC2616 policy

This policy provides a RFC2616 compliant HTTP cache, i.e. with HTTP Cache-Control awareness, aimed at production and used in continuous runs to avoid downloading unmodified data (to save bandwidth and speed up crawls).

what is implemented:

  • Do not attempt to store responses/requests with no-store cache-control directive set
  • Do not serve responses from cache if no-cache cache-control directive is set even for fresh responses
  • Compute freshness lifetime from max-age cache-control directive
  • Compute freshness lifetime from Expires response header
  • Compute freshness lifetime from Last-Modified response header (heuristic used by Firefox)
  • Compute current age from Age response header
  • Compute current age from Date header
  • Revalidate stale responses based on Last-Modified response header
  • Revalidate stale responses based on ETag response header
  • Set Date header for any received response missing it

what is missing:

In order to use this policy, set:

This is the default cache policy.

DBM storage backend (default)

System Message: ERROR/3 (<stdin>, line 378)

Unknown directive type "versionadded".

.. versionadded:: 0.13

A DBM storage backend is available for the HTTP cache middleware.

By default, it uses the anydbm module, but you can change it with the :setting:`HTTPCACHE_DBM_MODULE` setting.

System Message: ERROR/3 (<stdin>, line 382); backlink

Unknown interpreted text role "setting".

In order to use this storage backend, set:

Filesystem storage backend

A file system storage backend is also available for the HTTP cache middleware.

In order to use this storage backend, set:

Each request/response pair is stored in a different directory containing the following files:

  • request_body - the plain request body
  • request_headers - the request headers (in raw HTTP format)
  • response_body - the plain response body
  • response_headers - the request headers (in raw HTTP format)
  • meta - some metadata of this cache resource in Python repr() format (grep-friendly format)
  • pickled_meta - the same metadata in meta but pickled for more efficient deserialization

The directory name is made from the request fingerprint (see scrapy.utils.request.fingerprint), and one level of subdirectories is used to avoid creating too many files into the same directory (which is inefficient in many file systems). An example directory could be:

/path/to/cache/dir/example.com/72/72811f648e718090f041317756c03adb0ada46c7

HTTPCache middleware settings

The :class:`HttpCacheMiddleware` can be configured through the following settings:

System Message: ERROR/3 (<stdin>, line 424); backlink

Unknown interpreted text role "class".

System Message: ERROR/3 (<stdin>, line 427)

Unknown directive type "setting".

.. setting:: HTTPCACHE_ENABLED

HTTPCACHE_ENABLED

System Message: ERROR/3 (<stdin>, line 432)

Unknown directive type "versionadded".

.. versionadded:: 0.11

Default: False

Whether the HTTP cache will be enabled.

System Message: ERROR/3 (<stdin>, line 438)

Unknown directive type "versionchanged".

.. versionchanged:: 0.11
   Before 0.11, :setting:`HTTPCACHE_DIR` was used to enable cache.

System Message: ERROR/3 (<stdin>, line 441)

Unknown directive type "setting".

.. setting:: HTTPCACHE_EXPIRATION_SECS

HTTPCACHE_EXPIRATION_SECS

Default: 0

Expiration time for cached requests, in seconds.

Cached requests older than this time will be re-downloaded. If zero, cached requests will never expire.

System Message: ERROR/3 (<stdin>, line 453)

Unknown directive type "versionchanged".

.. versionchanged:: 0.11
   Before 0.11, zero meant cached requests always expire.

System Message: ERROR/3 (<stdin>, line 456)

Unknown directive type "setting".

.. setting:: HTTPCACHE_DIR

HTTPCACHE_DIR

Default: 'httpcache'

The directory to use for storing the (low-level) HTTP cache. If empty, the HTTP cache will be disabled. If a relative path is given, is taken relative to the project data dir. For more info see: :ref:`topics-project-structure`.

System Message: ERROR/3 (<stdin>, line 463); backlink

Unknown interpreted text role "ref".

System Message: ERROR/3 (<stdin>, line 467)

Unknown directive type "setting".

.. setting:: HTTPCACHE_IGNORE_HTTP_CODES

HTTPCACHE_IGNORE_HTTP_CODES

System Message: ERROR/3 (<stdin>, line 472)

Unknown directive type "versionadded".

.. versionadded:: 0.10

Default: []

Don't cache response with these HTTP codes.

System Message: ERROR/3 (<stdin>, line 478)

Unknown directive type "setting".

.. setting:: HTTPCACHE_IGNORE_MISSING

HTTPCACHE_IGNORE_MISSING

Default: False

If enabled, requests not found in the cache will be ignored instead of downloaded.

System Message: ERROR/3 (<stdin>, line 487)

Unknown directive type "setting".

.. setting:: HTTPCACHE_IGNORE_SCHEMES

HTTPCACHE_IGNORE_SCHEMES

System Message: ERROR/3 (<stdin>, line 492)

Unknown directive type "versionadded".

.. versionadded:: 0.10

Default: ['file']

Don't cache responses with these URI schemes.

System Message: ERROR/3 (<stdin>, line 498)

Unknown directive type "setting".

.. setting:: HTTPCACHE_STORAGE

HTTPCACHE_STORAGE

Default: 'scrapy.contrib.httpcache.DbmCacheStorage'

The class which implements the cache storage backend.

System Message: ERROR/3 (<stdin>, line 507)

Unknown directive type "setting".

.. setting:: HTTPCACHE_DBM_MODULE

HTTPCACHE_DBM_MODULE

System Message: ERROR/3 (<stdin>, line 512)

Unknown directive type "versionadded".

.. versionadded:: 0.13

Default: 'anydbm'

The database module to use in the :ref:`DBM storage backend <httpcache-storage-dbm>`. This setting is specific to the DBM backend.

System Message: ERROR/3 (<stdin>, line 516); backlink

Unknown interpreted text role "ref".

System Message: ERROR/3 (<stdin>, line 519)

Unknown directive type "setting".

.. setting:: HTTPCACHE_POLICY

HTTPCACHE_POLICY

System Message: ERROR/3 (<stdin>, line 524)

Unknown directive type "versionadded".

.. versionadded:: 0.18

Default: 'scrapy.contrib.httpcache.DummyPolicy'

The class which implements the cache policy.

HttpCompressionMiddleware

System Message: ERROR/3 (<stdin>, line 534)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.httpcompression
   :synopsis: Http Compression Middleware

This middleware allows compressed (gzip, deflate) traffic to be sent/received from web sites.

ChunkedTransferMiddleware

System Message: ERROR/3 (<stdin>, line 545)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.chunked
   :synopsis: Chunked Transfer Middleware

This middleware adds support for chunked transfer encoding

HttpProxyMiddleware

System Message: ERROR/3 (<stdin>, line 555)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.httpproxy
   :synopsis: Http Proxy Middleware

System Message: ERROR/3 (<stdin>, line 558)

Unknown directive type "versionadded".

.. versionadded:: 0.8

This middleware sets the HTTP proxy to use for requests, by setting the proxy meta value to :class:`~scrapy.http.Request` objects.

System Message: ERROR/3 (<stdin>, line 562); backlink

Unknown interpreted text role "class".

Like the Python standard library modules urllib and urllib2, it obeys the following environment variables:

  • http_proxy
  • https_proxy
  • no_proxy

RedirectMiddleware

System Message: ERROR/3 (<stdin>, line 578)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.redirect
   :synopsis: Redirection Middleware

This middleware handles redirection of requests based on response status.

System Message: ERROR/3 (<stdin>, line 585)

Unknown directive type "reqmeta".

.. reqmeta:: redirect_urls

The urls which the request goes through (while being redirected) can be found in the redirect_urls :attr:`Request.meta <scrapy.http.Request.meta>` key.

System Message: ERROR/3 (<stdin>, line 587); backlink

Unknown interpreted text role "attr".

The :class:`RedirectMiddleware` can be configured through the following settings (see the settings documentation for more info):

System Message: ERROR/3 (<stdin>, line 590); backlink

Unknown interpreted text role "class".

System Message: ERROR/3 (<stdin>, line 596)

Unknown directive type "reqmeta".

.. reqmeta:: dont_redirect

If :attr:`Request.meta <scrapy.http.Request.meta>` contains the dont_redirect key, the request will be ignored by this middleware.

System Message: ERROR/3 (<stdin>, line 598); backlink

Unknown interpreted text role "attr".

RedirectMiddleware settings

System Message: ERROR/3 (<stdin>, line 605)

Unknown directive type "setting".

.. setting:: REDIRECT_ENABLED

REDIRECT_ENABLED

System Message: ERROR/3 (<stdin>, line 610)

Unknown directive type "versionadded".

.. versionadded:: 0.13

Default: True

Whether the Redirect middleware will be enabled.

System Message: ERROR/3 (<stdin>, line 616)

Unknown directive type "setting".

.. setting:: REDIRECT_MAX_TIMES

REDIRECT_MAX_TIMES

Default: 20

The maximum number of redirections that will be follow for a single request.

MetaRefreshMiddleware

This middleware handles redirection of requests based on meta-refresh html tag.

The :class:`MetaRefreshMiddleware` can be configured through the following settings (see the settings documentation for more info):

System Message: ERROR/3 (<stdin>, line 632); backlink

Unknown interpreted text role "class".

This middleware obey :setting:`REDIRECT_MAX_TIMES` setting, :reqmeta:`dont_redirect` and :reqmeta:`redirect_urls` request meta keys as described for :class:`RedirectMiddleware`

System Message: ERROR/3 (<stdin>, line 638); backlink

Unknown interpreted text role "setting".

System Message: ERROR/3 (<stdin>, line 638); backlink

Unknown interpreted text role "reqmeta".

System Message: ERROR/3 (<stdin>, line 638); backlink

Unknown interpreted text role "reqmeta".

System Message: ERROR/3 (<stdin>, line 638); backlink

Unknown interpreted text role "class".

MetaRefreshMiddleware settings

System Message: ERROR/3 (<stdin>, line 645)

Unknown directive type "setting".

.. setting:: METAREFRESH_ENABLED

METAREFRESH_ENABLED

System Message: ERROR/3 (<stdin>, line 650)

Unknown directive type "versionadded".

.. versionadded:: 0.17

Default: True

Whether the Meta Refresh middleware will be enabled.

System Message: ERROR/3 (<stdin>, line 656)

Unknown directive type "setting".

.. setting:: REDIRECT_MAX_METAREFRESH_DELAY

REDIRECT_MAX_METAREFRESH_DELAY

Default: 100

The maximum meta-refresh delay (in seconds) to follow the redirection.

RetryMiddleware

System Message: ERROR/3 (<stdin>, line 668)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.retry
   :synopsis: Retry Middleware

A middlware to retry failed requests that are potentially caused by temporary problems such as a connection timeout or HTTP 500 error.

Failed pages are collected on the scraping process and rescheduled at the end, once the spider has finished crawling all regular (non failed) pages. Once there are no more failed pages to retry, this middleware sends a signal (retry_complete), so other extensions could connect to that signal.

The :class:`RetryMiddleware` can be configured through the following settings (see the settings documentation for more info):

System Message: ERROR/3 (<stdin>, line 681); backlink

Unknown interpreted text role "class".

About HTTP errors to consider:

You may want to remove 400 from :setting:`RETRY_HTTP_CODES`, if you stick to the HTTP protocol. It's included by default because it's a common code used to indicate server overload, which would be something we want to retry.

System Message: ERROR/3 (<stdin>, line 690); backlink

Unknown interpreted text role "setting".

System Message: ERROR/3 (<stdin>, line 694)

Unknown directive type "reqmeta".

.. reqmeta:: dont_retry

If :attr:`Request.meta <scrapy.http.Request.meta>` contains the dont_retry key, the request will be ignored by this middleware.

System Message: ERROR/3 (<stdin>, line 696); backlink

Unknown interpreted text role "attr".

RetryMiddleware Settings

System Message: ERROR/3 (<stdin>, line 702)

Unknown directive type "setting".

.. setting:: RETRY_ENABLED

RETRY_ENABLED

System Message: ERROR/3 (<stdin>, line 707)

Unknown directive type "versionadded".

.. versionadded:: 0.13

Default: True

Whether the Retry middleware will be enabled.

System Message: ERROR/3 (<stdin>, line 713)

Unknown directive type "setting".

.. setting:: RETRY_TIMES

RETRY_TIMES

Default: 2

Maximum number of times to retry, in addition to the first download.

System Message: ERROR/3 (<stdin>, line 722)

Unknown directive type "setting".

.. setting:: RETRY_HTTP_CODES

RETRY_HTTP_CODES

Default: [500, 502, 503, 504, 400, 408]

Which HTTP response codes to retry. Other errors (DNS lookup issues, connections lost, etc) are always retried.

RobotsTxtMiddleware

System Message: ERROR/3 (<stdin>, line 737)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.robotstxt
   :synopsis: robots.txt middleware

This middleware filters out requests forbidden by the robots.txt exclusion standard.

To make sure Scrapy respects robots.txt make sure the middleware is enabled and the :setting:`ROBOTSTXT_OBEY` setting is enabled.

System Message: ERROR/3 (<stdin>, line 745); backlink

Unknown interpreted text role "setting".

Warning

Keep in mind that, if you crawl using multiple concurrent requests per domain, Scrapy could still download some forbidden pages if they were requested before the robots.txt file was downloaded. This is a known limitation of the current robots.txt middleware and will be fixed in the future.

DownloaderStats

System Message: ERROR/3 (<stdin>, line 757)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.stats
   :synopsis: Downloader Stats Middleware

Middleware that stores stats of all requests, responses and exceptions that pass through it.

To use this middleware you must enable the :setting:`DOWNLOADER_STATS` setting.

System Message: ERROR/3 (<stdin>, line 765); backlink

Unknown interpreted text role "setting".

UserAgentMiddleware

System Message: ERROR/3 (<stdin>, line 771)

Unknown directive type "module".

.. module:: scrapy.contrib.downloadermiddleware.useragent
   :synopsis: User Agent Middleware

Middleware that allows spiders to override the default user agent.

In order for a spider to override the default user agent, its user_agent attribute must be set.

</html>