Requests and Responses¶
Scrapy uses Request
and Response
objects for crawling web
sites.
Typically, Request
objects are generated in the spiders and pass
across the system until they reach the Downloader, which executes the request
and returns a Response
object which travels back to the spider that
issued the request.
Both Request
and Response
classes have subclasses which add
functionality not required in the base classes. These are described
below in Request subclasses and
Response subclasses.
Request objects¶
- class scrapy.http.Request(*args: Any, **kwargs: Any)[source]¶
Represents an HTTP request, which is usually generated in a Spider and executed by the Downloader, thus generating a
Response
.- Parameters:
url (str) –
the URL of this request
If the URL is invalid, a
ValueError
exception is raised.callback (collections.abc.Callable) –
the function that will be called with the response of this request (once it’s downloaded) as its first parameter.
In addition to a function, the following values are supported:
None
(default), which indicates that the spider’sparse()
method must be used.
For more information, see Passing additional data to callback functions.
Note
If exceptions are raised during processing,
errback
is called instead.method (str) – the HTTP method of this request. Defaults to
'GET'
.meta (dict) – the initial values for the
Request.meta
attribute. If given, the dict passed in this parameter will be shallow copied.body (bytes or str) – the request body. If a string is passed, then it’s encoded as bytes using the
encoding
passed (which defaults toutf-8
). Ifbody
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 orNone
).headers (dict) –
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 CookiesMiddleware. If you need to set cookies for a request, use theRequest.cookies
parameter. This is a known current limitation that is being worked on.the request cookies. These can be sent in two forms.
Using a dict:
request_with_cookies = Request( url="http://www.example.com", cookies={"currency": "USD", "country": "UY"}, )
Using a list of dicts:
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
andpath
attributes of the cookie. This is only useful if the cookies are saved for later requests.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
dont_merge_cookies
key toTrue
inrequest.meta
causes custom cookies to be ignored.For more info see CookiesMiddleware.
Caution
Cookies set via the
Cookie
header are not considered by the CookiesMiddleware. If you need to set cookies for a request, use theRequest.cookies
parameter. This is a known current limitation that is being worked on.encoding (str) – 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).priority (int) – the priority of this request (defaults to
0
). The priority is used by the scheduler to define the order used to process requests. Requests with a higher priority value will execute earlier. Negative values are allowed in order to indicate relatively low-priority.dont_filter (bool) – indicates that this request should not be filtered by the scheduler. This is used when you want to perform an identical request multiple times, to ignore the duplicates filter. Use it with care, or you will get into crawling loops. Default to
False
.errback (collections.abc.Callable) –
a function that will be called if any exception was raised while processing the request. This includes pages that failed with 404 HTTP errors and such. It receives a
Failure
as first parameter. For more information, see Using errbacks to catch exceptions in request processing below.Changed in version 2.0: The callback parameter is no longer required when the errback parameter is specified.
flags (list) – Flags sent to the request, can be used for logging or similar purposes.
cb_kwargs (dict) – A dict with arbitrary data that will be passed as keyword arguments to the Request’s callback.
- 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.This attribute is read-only. To change the URL of a Request use
replace()
.
- method¶
A string representing the HTTP method in the request. This is guaranteed to be uppercase. Example:
"GET"
,"POST"
,"PUT"
, etc
- headers¶
A dictionary-like object which contains the request headers.
- body¶
The request body as bytes.
This attribute is read-only. To change the body of a Request use
replace()
.
- meta = {}¶
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
meta
attribute of a response.To pass data from one spider callback to another, consider using
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
toTrue
,RetryMiddleware
will never retry that request, even if it fails. See Request.meta special keys.You may also use request metadata in your custom Scrapy components, for example, to keep request state information relevant to your component. For example,
RetryMiddleware
uses theretry_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 downloader middleware method.
Also mind that the
copy()
andreplace()
request methods shallow-copy request metadata.
- 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
Response
object as argument.This dict is shallow copied when the request is cloned using the
copy()
orreplace()
methods, and can also be accessed, in your spider, from theresponse.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 Accessing additional data in errback functions.
- attributes: tuple[str, ...] = ('url', 'callback', 'method', 'headers', 'body', 'cookies', 'meta', 'encoding', 'priority', 'dont_filter', 'errback', 'flags', 'cb_kwargs')¶
A tuple of
str
objects containing the name of all public attributes of the class that are also keyword parameters of the__init__
method.Currently used by
Request.replace()
,Request.to_dict()
andrequest_from_dict()
.
- copy()[source]¶
Return a new Request which is a copy of this Request. See also: Passing additional data to callback functions.
- replace([url, method, headers, body, cookies, meta, flags, encoding, priority, dont_filter, callback, errback, cb_kwargs])[source]¶
Return a Request object with the same members, except for those members given new values by whichever keyword arguments are specified. The
Request.cb_kwargs
andRequest.meta
attributes are shallow copied by default (unless new values are given as arguments). See also Passing additional data to callback functions.
- classmethod from_curl(curl_command: str, ignore_unknown_options: bool = True, **kwargs: Any) Self [source]¶
Create a Request object from a string containing a cURL command. It populates the HTTP method, the URL, the headers, the cookies and the body. It accepts the same arguments as the
Request
class, taking preference and overriding the values of the same arguments contained in the cURL command.Unrecognized options are ignored by default. To raise an error when finding unknown options call this method by passing
ignore_unknown_options=False
.Caution
Using
from_curl()
fromRequest
subclasses, such asJsonRequest
, orXmlRpcRequest
, as well as having downloader middlewares and spider middlewares enabled, such asDefaultHeadersMiddleware
,UserAgentMiddleware
, orHttpCompressionMiddleware
, may modify theRequest
object.To translate a cURL command into a Scrapy request, you may use curl2scrapy.
- to_dict(*, spider: Spider | None = None) dict[str, Any] [source]¶
Return a dictionary containing the Request’s data.
Use
request_from_dict()
to convert back into aRequest
object.If a spider is given, this method will try to find out the name of the spider methods used as callback and errback and include them in the output dict, raising an exception if they cannot be found.
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 Response
object as its first argument.
Example:
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
Request.cb_kwargs
attribute:
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
Request.cb_kwargs
was introduced in version 1.7
.
Prior to that, using Request.meta
was recommended for passing
information around callbacks. After 1.7
, Request.cb_kwargs
became the preferred way for handling user information, leaving Request.meta
for communication with components like middlewares and extensions.
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 Failure
as first parameter and can
be used to track connection establishment timeouts, DNS errors etc.
Here’s an example spider logging all errors and catching some specific errors if needed:
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
]
def start_requests(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
:
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 DUPEFILTER_CLASS
) or caching responses (see
HTTPCACHE_POLICY
), where you need the ability to generate a short,
unique identifier from a 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
REQUEST_FINGERPRINTER_CLASS
setting.
REQUEST_FINGERPRINTER_CLASS¶
New in version 2.7.
Default: scrapy.utils.request.RequestFingerprinter
A request fingerprinter class or its import path.
- class scrapy.utils.request.RequestFingerprinter(crawler: Crawler | None = None)[source]¶
Default fingerprinter.
It takes into account a canonical version (
w3lib.url.canonicalize_url()
) ofrequest.url
and the values ofrequest.method
andrequest.body
. It then generates an SHA1 hash.See also
REQUEST_FINGERPRINTER_IMPLEMENTATION
.
Writing your own request fingerprinter¶
A request fingerprinter is a class that must implement the following method:
- fingerprint(self, request)¶
Return a
bytes
object that uniquely identifies request.See also Request fingerprint restrictions.
- Parameters:
request (scrapy.http.Request) – request to fingerprint
Additionally, it may also implement the following method:
- classmethod from_crawler(cls, crawler)
If present, this class method is called to create a request fingerprinter instance from a
Crawler
object. It must return a new instance of the request fingerprinter.crawler provides access to all Scrapy core components like settings and signals; it is a way for the request fingerprinter to access them and hook its functionality into Scrapy.
- Parameters:
crawler (
Crawler
object) – crawler that uses this request fingerprinter
The fingerprint()
method of the default request fingerprinter,
scrapy.utils.request.RequestFingerprinter
, uses
scrapy.utils.request.fingerprint()
with its default parameters. For some
common use cases you can use scrapy.utils.request.fingerprint()
as well
in your fingerprint()
method implementation:
- scrapy.utils.request.fingerprint(request: Request, *, include_headers: Iterable[bytes | str] | None = None, keep_fragments: bool = False) bytes [source]¶
Return the request fingerprint.
The request fingerprint is a hash that uniquely identifies the resource the request points to. For example, take the following two urls:
http://www.example.com/query?id=111&cat=222
,http://www.example.com/query?cat=222&id=111
.Even though those are two different URLs both point to the same resource and are equivalent (i.e. they should return the same response).
Another example are cookies used to store session ids. Suppose the following page is only accessible to authenticated users:
http://www.example.com/members/offers.html
.Lots of sites use a cookie to store the session id, which adds a random component to the HTTP Request and thus should be ignored when calculating the fingerprint.
For this reason, request headers are ignored by default when calculating the fingerprint. If you want to include specific headers use the include_headers argument, which is a list of Request headers to include.
Also, servers usually ignore fragments in urls when handling requests, so they are also ignored by default when calculating the fingerprint. If you want to include them, set the keep_fragments argument to True (for instance when handling requests with a headless browser).
For example, to take the value of a request header named X-ID
into
account:
# 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 scrapy.utils.request.fingerprint()
, make sure
you use 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
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:
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 request.meta
when available, and then falls back to
scrapy.utils.request.fingerprint()
. For example:
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
without using the deprecated '2.6'
value of the
REQUEST_FINGERPRINTER_IMPLEMENTATION
setting, use the following
request fingerprinter:
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 request fingerprinter generates.
The following built-in Scrapy components have such restrictions:
scrapy.extensions.httpcache.FilesystemCacheStorage
(default value ofHTTPCACHE_STORAGE
)Request fingerprints must be at least 1 byte long.
Path and filename length limits of the file system of
HTTPCACHE_DIR
also apply. InsideHTTPCACHE_DIR
, the following directory structure is created: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),
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
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.
Request.meta special keys¶
The Request.meta
attribute can contain any arbitrary data, but there
are some special keys recognized by Scrapy and its built-in extensions.
Those are:
ftp_password
(SeeFTP_PASSWORD
for more info)ftp_user
(SeeFTP_USER
for more info)
bindaddress¶
The IP of the outgoing IP address to use for the performing the request.
download_timeout¶
The amount of time (in secs) that the downloader will wait before timing out.
See also: DOWNLOAD_TIMEOUT
.
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.
download_fail_on_dataloss¶
Whether or not to fail on broken responses. See:
DOWNLOAD_FAIL_ON_DATALOSS
.
max_retry_times¶
The meta key is used set retry times per request. When initialized, the
max_retry_times
meta key takes higher precedence over the
RETRY_TIMES
setting.
Stopping the download of a Response¶
Raising a StopDownload
exception from a handler for the
bytes_received
or headers_received
signals will stop the download of a given response. See the following example:
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
StopDownload
exception.
Request subclasses¶
Here is the list of built-in Request
subclasses. You can also subclass
it to implement your own custom functionality.
FormRequest objects¶
The FormRequest class extends the base Request
with functionality for
dealing with HTML forms. It uses lxml.html forms to pre-populate form
fields with form data from Response
objects.
- class scrapy.http.request.form.FormRequest¶
- class scrapy.http.FormRequest¶
- class scrapy.FormRequest(url[, formdata, ...])¶
The
FormRequest
class adds a new keyword parameter to the__init__
method. The remaining arguments are the same as for theRequest
class and are not documented here.- Parameters:
formdata (dict or collections.abc.Iterable) – is a dictionary (or iterable of (key, value) tuples) containing HTML Form data which will be url-encoded and assigned to the body of the request.
The
FormRequest
objects support the following class method in addition to the standardRequest
methods:- classmethod FormRequest.from_response(response[, formname=None, formid=None, formnumber=0, formdata=None, formxpath=None, formcss=None, clickdata=None, dont_click=False, ...])¶
Returns a new
FormRequest
object with its form field values pre-populated with those found in the HTML<form>
element contained in the given response. For an example see Using FormRequest.from_response() to simulate a user login.The policy is to automatically simulate a click, by default, on any form control that looks clickable, like a
<input type="submit">
. Even though this is quite convenient, and often the desired behaviour, sometimes it can cause problems which could be hard to debug. For example, when working with forms that are filled and/or submitted using javascript, the defaultfrom_response()
behaviour may not be the most appropriate. To disable this behaviour you can set thedont_click
argument toTrue
. Also, if you want to change the control clicked (instead of disabling it) you can also use theclickdata
argument.Caution
Using this method with select elements which have leading or trailing whitespace in the option values will not work due to a bug in lxml, which should be fixed in lxml 3.8 and above.
- Parameters:
response (
Response
object) – the response containing a HTML form which will be used to pre-populate the form fieldsformname (str) – if given, the form with name attribute set to this value will be used.
formid (str) – if given, the form with id attribute set to this value will be used.
formxpath (str) – if given, the first form that matches the xpath will be used.
formcss (str) – if given, the first form that matches the css selector will be used.
formnumber (int) – the number of form to use, when the response contains multiple forms. The first one (and also the default) is
0
.formdata (dict) – fields to override in the form data. If a field was already present in the response
<form>
element, its value is overridden by the one passed in this parameter. If a value passed in this parameter isNone
, the field will not be included in the request, even if it was present in the response<form>
element.clickdata (dict) – attributes to lookup the control clicked. If it’s not given, the form data will be submitted simulating a click on the first clickable element. In addition to html attributes, the control can be identified by its zero-based index relative to other submittable inputs inside the form, via the
nr
attribute.dont_click (bool) – If True, the form data will be submitted without clicking in any element.
The other parameters of this class method are passed directly to the
FormRequest
__init__
method.
Request usage examples¶
Using FormRequest to send data via HTTP POST¶
If you want to simulate a HTML Form POST in your spider and send a couple of
key-value fields, you can return a FormRequest
object (from your
spider) like this:
return [
FormRequest(
url="http://www.example.com/post/action",
formdata={"name": "John Doe", "age": "27"},
callback=self.after_post,
)
]
Using FormRequest.from_response() 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). When scraping, you’ll want these fields to be
automatically pre-populated and only override a couple of them, such as the
user name and password. You can use the FormRequest.from_response()
method for this job. Here’s an example spider which uses it:
import scrapy
def authentication_failed(response):
# TODO: Check the contents of the response and return True if it failed
# or False if it succeeded.
pass
class LoginSpider(scrapy.Spider):
name = "example.com"
start_urls = ["http://www.example.com/users/login.php"]
def parse(self, response):
return scrapy.FormRequest.from_response(
response,
formdata={"username": "john", "password": "secret"},
callback=self.after_login,
)
def after_login(self, response):
if authentication_failed(response):
self.logger.error("Login failed")
return
# continue scraping with authenticated session...
JsonRequest¶
The JsonRequest class extends the base Request
class with functionality for
dealing with JSON requests.
- class scrapy.http.JsonRequest(url[, ... data, dumps_kwargs])[source]¶
The
JsonRequest
class adds two new keyword parameters to the__init__
method. The remaining arguments are the same as for theRequest
class and are not documented here.Using the
JsonRequest
will set theContent-Type
header toapplication/json
andAccept
header toapplication/json, text/javascript, */*; q=0.01
- Parameters:
data (object) – is any JSON serializable object that needs to be JSON encoded and assigned to body. if
Request.body
argument is provided this parameter will be ignored. ifRequest.body
argument is not provided and data argument is providedRequest.method
will be set to'POST'
automatically.dumps_kwargs (dict) – Parameters that will be passed to underlying
json.dumps()
method which is used to serialize data into JSON format.
- attributes: tuple[str, ...] = ('url', 'callback', 'method', 'headers', 'body', 'cookies', 'meta', 'encoding', 'priority', 'dont_filter', 'errback', 'flags', 'cb_kwargs', 'dumps_kwargs')¶
A tuple of
str
objects containing the name of all public attributes of the class that are also keyword parameters of the__init__
method.Currently used by
Request.replace()
,Request.to_dict()
andrequest_from_dict()
.
JsonRequest usage example¶
Sending a JSON POST request with a JSON payload:
data = {
"name1": "value1",
"name2": "value2",
}
yield JsonRequest(url="http://www.example.com/post/action", data=data)
Response objects¶
- class scrapy.http.Response(*args: Any, **kwargs: Any)[source]¶
An object that represents an HTTP response, which is usually downloaded (by the Downloader) and fed to the Spiders for processing.
- Parameters:
url (str) – the URL of this response
status (int) – the HTTP status of the response. Defaults to
200
.headers (dict) – the headers of this response. The dict values can be strings (for single valued headers) or lists (for multi-valued headers).
body (bytes) – the response body. To access the decoded text as a string, use
response.text
from an encoding-aware Response subclass, such asTextResponse
.flags (list) – is a list containing the initial values for the
Response.flags
attribute. If given, the list will be shallow copied.request (scrapy.Request) – the initial value of the
Response.request
attribute. This represents theRequest
that generated this response.certificate (twisted.internet.ssl.Certificate) – an object representing the server’s SSL certificate.
ip_address (
ipaddress.IPv4Address
oripaddress.IPv6Address
) – The IP address of the server from which the Response originated.protocol (
str
) – The protocol that was used to download the response. For instance: “HTTP/1.0”, “HTTP/1.1”, “h2”
New in version 2.0.0: The
certificate
parameter.New in version 2.1.0: The
ip_address
parameter.New in version 2.5.0: The
protocol
parameter.- url¶
A string containing the URL of the response.
This attribute is read-only. To change the URL of a Response use
replace()
.
- status¶
An integer representing the HTTP status of the response. Example:
200
,404
.
- headers¶
A dictionary-like object which contains the response headers. Values can be accessed using
get()
to return the first header value with the specified name orgetlist()
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')
- body¶
The response body as bytes.
If you want the body as a string, use
TextResponse.text
(only available inTextResponse
and subclasses).This attribute is read-only. To change the body of a Response use
replace()
.
- request¶
The
Request
object that generated this response. This attribute is assigned in the Scrapy engine, after the response and the request have passed through all Downloader Middlewares. 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 Spider Middlewares, but not in Downloader Middlewares (although you have the Request available there by other means) and handlers of the
response_downloaded
signal.
- meta¶
A shortcut to the
Request.meta
attribute of theResponse.request
object (i.e.self.request.meta
).Unlike the
Response.request
attribute, theResponse.meta
attribute is propagated along redirects and retries, so you will get the originalRequest.meta
sent from your spider.See also
Request.meta
attribute
- cb_kwargs¶
New in version 2.0.
A shortcut to the
Request.cb_kwargs
attribute of theResponse.request
object (i.e.self.request.cb_kwargs
).Unlike the
Response.request
attribute, theResponse.cb_kwargs
attribute is propagated along redirects and retries, so you will get the originalRequest.cb_kwargs
sent from your spider.See also
Request.cb_kwargs
attribute
- 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.
- certificate¶
New in version 2.0.0.
A
twisted.internet.ssl.Certificate
object representing the server’s SSL certificate.Only populated for
https
responses,None
otherwise.
- ip_address¶
New in version 2.1.0.
The IP address of the server from which the Response originated.
This attribute is currently only populated by the HTTP 1.1 download handler, i.e. for
http(s)
responses. For other handlers,ip_address
is alwaysNone
.
- protocol¶
New in version 2.5.0.
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,protocol
is alwaysNone
.
- attributes: tuple[str, ...] = ('url', 'status', 'headers', 'body', 'flags', 'request', 'certificate', 'ip_address', 'protocol')¶
A tuple of
str
objects containing the name of all public attributes of the class that are also keyword parameters of the__init__
method.Currently used by
Response.replace()
.
- replace([url, status, headers, body, request, flags, cls])[source]¶
Returns a Response object with the same members, except for those members given new values by whichever keyword arguments are specified. The attribute
Response.meta
is copied by default.
- urljoin(url)[source]¶
Constructs an absolute url by combining the Response’s
url
with a possible relative url.This is a wrapper over
urljoin()
, it’s merely an alias for making this call:urllib.parse.urljoin(response.url, url)
- follow(url: str | Link, callback: CallbackT | None = None, method: str = 'GET', headers: Mapping[AnyStr, Any] | Iterable[tuple[AnyStr, Any]] | None = None, body: bytes | str | None = None, cookies: CookiesT | None = None, meta: dict[str, Any] | None = None, encoding: str | None = 'utf-8', priority: int = 0, dont_filter: bool = False, errback: Callable[[Failure], Any] | None = None, cb_kwargs: dict[str, Any] | None = None, flags: list[str] | None = None) Request [source]¶
Return a
Request
instance to follow a linkurl
. It accepts the same arguments asRequest.__init__
method, buturl
can be a relative URL or ascrapy.link.Link
object, not only an absolute URL.TextResponse
provides afollow()
method which supports selectors in addition to absolute/relative URLs and Link objects.New in version 2.0: The flags parameter.
- follow_all(urls: Iterable[str | Link], callback: CallbackT | None = None, method: str = 'GET', headers: Mapping[AnyStr, Any] | Iterable[tuple[AnyStr, Any]] | None = None, body: bytes | str | None = None, cookies: CookiesT | None = None, meta: dict[str, Any] | None = None, encoding: str | None = 'utf-8', priority: int = 0, dont_filter: bool = False, errback: Callable[[Failure], Any] | None = None, cb_kwargs: dict[str, Any] | None = None, flags: list[str] | None = None) Iterable[Request] [source]¶
New in version 2.0.
Return an iterable of
Request
instances to follow all links inurls
. It accepts the same arguments asRequest.__init__
method, but elements ofurls
can be relative URLs orLink
objects, not only absolute URLs.TextResponse
provides afollow_all()
method which supports selectors in addition to absolute/relative URLs and Link objects.
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 scrapy.http.TextResponse(url[, encoding[, ...]])[source]¶
TextResponse
objects adds encoding capabilities to the baseResponse
class, which is meant to be used only for binary data, such as images, sounds or any media file.TextResponse
objects support a new__init__
method argument, in addition to the baseResponse
objects. The remaining functionality is the same as for theResponse
class and is not documented here.- Parameters:
encoding (str) – is a string which contains the encoding to use for this response. If you create a
TextResponse
object with a string as body, it will be converted to bytes encoded using this encoding. If encoding isNone
(default), the encoding will be looked up in the response headers and body instead.
TextResponse
objects support the following attributes in addition to the standardResponse
ones:- 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 accessresponse.text
multiple times without extra overhead.Note
str(response.body)
is not a correct way to convert the response body into a string:>>> str(b"body") "b'body'"
- encoding¶
A string with the encoding of this response. The encoding is resolved by trying the following mechanisms, in order:
the encoding passed in the
__init__
methodencoding
argumentthe 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.
the encoding declared in the response body. The TextResponse class doesn’t provide any special functionality for this. However, the
HtmlResponse
andXmlResponse
classes do.the encoding inferred by looking at the response body. This is the more fragile method but also the last one tried.
- selector¶
A
Selector
instance using the response as target. The selector is lazily instantiated on first access.
- attributes: tuple[str, ...] = ('url', 'status', 'headers', 'body', 'flags', 'request', 'certificate', 'ip_address', 'protocol', 'encoding')¶
A tuple of
str
objects containing the name of all public attributes of the class that are also keyword parameters of the__init__
method.Currently used by
Response.replace()
.
TextResponse
objects support the following methods in addition to the standardResponse
ones:- jmespath(query)[source]¶
A shortcut to
TextResponse.selector.jmespath(query)
:response.jmespath('object.[*]')
- follow(url: str | Link | parsel.Selector, callback: CallbackT | None = None, method: str = 'GET', headers: Mapping[AnyStr, Any] | Iterable[tuple[AnyStr, Any]] | None = None, body: bytes | str | None = None, cookies: CookiesT | None = None, meta: dict[str, Any] | None = None, encoding: str | None = None, priority: int = 0, dont_filter: bool = False, errback: Callable[[Failure], Any] | None = None, cb_kwargs: dict[str, Any] | None = None, flags: list[str] | None = None) Request [source]¶
Return a
Request
instance to follow a linkurl
. It accepts the same arguments asRequest.__init__
method, buturl
can be not only an absolute URL, but alsoa relative URL
a
Link
object, e.g. the result of Link Extractorsa
Selector
object for a<link>
or<a>
element, e.g.response.css('a.my_link')[0]
an attribute
Selector
(not SelectorList), e.g.response.css('a::attr(href)')[0]
orresponse.xpath('//img/@src')[0]
See A shortcut for creating Requests for usage examples.
- follow_all(urls: Iterable[str | Link] | parsel.SelectorList | None = None, callback: CallbackT | None = None, method: str = 'GET', headers: Mapping[AnyStr, Any] | Iterable[tuple[AnyStr, Any]] | None = None, body: bytes | str | None = None, cookies: CookiesT | None = None, meta: dict[str, Any] | None = None, encoding: str | None = None, priority: int = 0, dont_filter: bool = False, errback: Callable[[Failure], Any] | None = None, cb_kwargs: dict[str, Any] | None = None, flags: list[str] | None = None, css: str | None = None, xpath: str | None = None) Iterable[Request] [source]¶
A generator that produces
Request
instances to follow all links inurls
. It accepts the same arguments as theRequest
’s__init__
method, except that eachurls
element does not need to be an absolute URL, it can be any of the following:a relative URL
a
Link
object, e.g. the result of Link Extractorsa
Selector
object for a<link>
or<a>
element, e.g.response.css('a.my_link')[0]
an attribute
Selector
(not SelectorList), e.g.response.css('a::attr(href)')[0]
orresponse.xpath('//img/@src')[0]
In addition,
css
andxpath
arguments are accepted to perform the link extraction within thefollow_all
method (only one ofurls
,css
andxpath
is accepted).Note that when passing a
SelectorList
as argument for theurls
parameter or using thecss
orxpath
parameters, this method will not produce requests for selectors from which links cannot be obtained (for instance, anchor tags without anhref
attribute)
HtmlResponse objects¶
- class scrapy.http.HtmlResponse(url[, ...])[source]¶
The
HtmlResponse
class is a subclass ofTextResponse
which adds encoding auto-discovering support by looking into the HTML meta http-equiv attribute. SeeTextResponse.encoding
.
XmlResponse objects¶
- class scrapy.http.XmlResponse(url[, ...])[source]¶
The
XmlResponse
class is a subclass ofTextResponse
which adds encoding auto-discovering support by looking into the XML declaration line. SeeTextResponse.encoding
.
JsonResponse objects¶
- class scrapy.http.JsonResponse(url[, ...])[source]¶
The
JsonResponse
class is a subclass ofTextResponse
that is used when the response has a JSON MIME type in its Content-Type header.