scrapy-rss

========== scrapy_rss

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Tools to easy generate RSS feed <http://www.rssboard.org/rss-specification>_ that contains each scraped item using Scrapy framework <https://github.com/scrapy/scrapy>_.

Table of Contents

• Installation <#installation>__

• How To Use <#how-to-use>__

  • Configuration <#configuration>__

  • Optional Additional Customization <#feed-channel-elements-customization-optionally>__

  • Usage <#usage>__

    • Basic usage <#basic-usage>__
    • RssItem derivation and namespaces <#rssitem-derivation-and-namespaces>__

• Scrapy Project Examples <#scrapy-project-examples>__

Installation <https://packaging.python.org/installing/>_

• Install :code:scrapy_rss using pip

  .. code:: bash

   pip install scrapy_rss
  

  or using pip for the specific interpreter, e.g.:

  .. code:: bash

  pip3 install scrapy_rss
  

• or using setuptools directly:

  .. code:: bash

  cd path/to/root/of/scrapy_rss
  python setup.py install
  

  or using setuptools for specific interpreter, e.g.:

  .. code:: bash

  cd path/to/root/of/scrapy_rss
  python3 setup.py install
  

How To Use

Configuration

Add parameters to the Scrapy project settings (settings.py file) or to the :code:custom_settings attribute of the spider:

1. Add item pipeline that export items to rss feed:

   .. code:: python

   ITEM_PIPELINES = { # ... 'scrapy_rss.pipelines.RssExportPipeline': 900, # or another priority # ... }

2. Add required feed parameters:

   FEED_FILE the absolute or relative file path where the result RSS feed will be saved. For example, :code:feed.rss or :code:output/feed.rss. FEED_TITLE the name of the channel (feed), FEED_DESCRIPTION the phrase or sentence that describes the channel (feed), FEED_LINK the URL to the HTML website corresponding to the channel (feed)

   .. code:: python

   FEED_FILE = 'path/to/feed.rss' FEED_TITLE = 'Some title of the channel' FEED_LINK = 'http://example.com/rss' FEED_DESCRIPTION = 'About channel'

Feed (Channel) Elements Customization [optionally]

If you want to change other channel parameters (such as language, copyright, managing_editor, webmaster, pubdate, last_build_date, category, generator, docs, ttl) then define your own exporter that's inherited from :code:RssItemExporter class, for example:

.. code:: python

from scrapy_rss.exporters import RssItemExporter

class MyRssItemExporter(RssItemExporter): def init(self, *args, **kwargs): kwargs['generator'] = kwargs.get('generator', 'Special generator') kwargs['language'] = kwargs.get('language', 'en-us') super(MyRssItemExporter, self).init(*args, **kwargs)

And add :code:FEED_EXPORTER parameter to the Scrapy project settings or to the :code:custom_settings attribute of the spider:

.. code:: python

FEED_EXPORTER = 'myproject.exporters.MyRssItemExporter'

Usage

Basic usage ^^^^^^^^^^^

Declare your item directly as RssItem():

.. code:: python

import scrapy_rss

item1 = scrapy_rss.RssItem()

Or use predefined item class :code:RssedItem with RSS field named as :code:rss that's instance of :code:RssItem:

.. code:: python

import scrapy import scrapy_rss

class MyItem(scrapy_rss.RssedItem): field1 = scrapy.Field() field2 = scrapy.Field() # ...

item2 = MyItem()

Set/get item fields. Case sensitive attributes of :code:RssItem() are appropriate to RSS elements. Attributes of RSS elements are case sensitive too. If the editor allows autocompletion then it suggests attributes for instances of :code:RssedItem and :code:RssItem. It's allowed to set any subset of RSS elements (e.g. title only). For example:

.. code:: python

from datetime import datetime

item1.title = 'RSS item title' # set value of element title = item1.title.title # get value of <title> element item1.description = 'description'

item1.guid = 'item identifier' item1.guid.isPermaLink = True # set value of attribute isPermalink of <guid> element, # isPermaLink is False by default is_permalink = item1.guid.isPermaLink # get value of attribute isPermalink of <guid> element guid = item1.guid.guid # get value of element <guid>

item1.category = 'single category' category = item1.category item1.category = ['first category', 'second category'] first_category = item1.category[0].category # get value of the element with multiple values all_categories = [cat.category for cat in item1.category]

direct attributes setting

item1.enclosure.url = 'http://example.com/file' item1.enclosure.length = 0 item1.enclosure.type = 'text/plain'

or dict based attributes setting

item1.enclosure = {'url': 'http://example.com/file', 'length': 0, 'type': 'text/plain'} item1.guid = {'guid': 'item identifier', 'isPermaLink': True}

item1.pubDate = datetime.now() # correctly works with Python' datetimes

item2.rss.title = 'Item title' item2.rss.guid = 'identifier' item2.rss.enclosure = {'url': 'http://example.com/file', 'length': 0, 'type': 'text/plain'}

All allowed elements are listed in the scrapy_rss/items.py <https://github.com/woxcab/scrapy_rss/blob/master/scrapy_rss/items.py>. All allowed attributes of each element with constraints and default values are listed in the scrapy_rss/elements.py <https://github.com/woxcab/scrapy_rss/blob/master/scrapy_rss/elements.py>. Also you can read RSS specification <http://www.rssboard.org/rss-specification>_ for more details.

:code:RssItem derivation and namespaces ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

You can extend RssItem to add new XML fields that can be namespaced or not. You can specify namespaces in an attribute and/or an element constructors. Namespace prefix can be specified in the attribute/element name using double underscores as delimiter (:code:prefix__name) or in the attribute/element constructor using :code:ns_prefix argument. Namespace URI can be specified using :code:ns_uri argument of the constructor.

.. code:: python

from scrapy_rss.meta import ItemElementAttribute, ItemElement
from scrapy_rss.items import RssItem

class Element0(ItemElement):
    # attributes without special namespace
    attr0 = ItemElementAttribute(is_content=True, required=True)
    attr1 = ItemElementAttribute()

class Element1(ItemElement):
    # attribute "prefix2:attr2" with namespace xmlns:prefix2="id2"
    attr2 = ItemElementAttribute(ns_prefix="prefix2", ns_uri="id2")

    # attribute "prefix3:attr3" with namespace xmlns:prefix3="id3"
    prefix3__attr3 = ItemElementAttribute(ns_uri="id3")

    # attribute "prefix4:attr4" with namespace xmlns:prefix4="id4"
    fake_prefix__attr4 = ItemElementAttribute(ns_prefix="prefix4", ns_uri="id4")

    # attribute "attr5" with default namespace xmlns="id5"
    attr5 = ItemElementAttribute(ns_uri="id5")

class MyXMLItem(RssItem):
    # element <elem1> without namespace
    elem1 = Element0()

    # element <elem_prefix2:elem2> with namespace xmlns:elem_prefix2="id2e"
    elem2 = Element0(ns_prefix="elem_prefix2", ns_uri="id2e")

    # element <elem_prefix3:elem3> with namespace xmlns:elem_prefix3="id3e"
    elem_prefix3__elem3 = Element1(ns_uri="id3e")

    # yet another element <elem_prefix4:elem3> with namespace xmlns:elem_prefix4="id4e"
    # (does not conflict with previous one)
    fake_prefix__elem3 = Element0(ns_prefix="elem_prefix4", ns_uri="id4e")

    # element <elem5> with default namespace xmlns="id5e"
    elem5 = Element0(ns_uri="id5e")

Access to elements and its attributes is the same as with simple items:

.. code:: python

item = MyXMLItem()
item.title = 'Some title'
item.elem1.attr0 = 'Required content value'
item.elem1 = 'Another way to set content value'
item.elem1.attr1 = 'Some attribute value'
item.elem_prefix3__elem3.prefix3__attr3 = 'Yet another attribute value'
item.elem_prefix3__elem3.fake_prefix__attr4 = '' # non-None value is interpreted as assigned
item.fake_prefix__elem3.attr1 = 42

Several optional settings are allowed for namespaced items:

FEED_NAMESPACES list of tuples :code:[(prefix, URI), ...] or dictionary :code:{prefix: URI, ...} of namespaces that must be defined in the root XML element

FEED_ITEM_CLASS or FEED_ITEM_CLS main class of feed items (class object :code:MyXMLItem or path to class :code:"path.to.MyXMLItem"). Default value: :code:RssItem. It's used in order to extract all possible namespaces that will be declared in the root XML element.

Feed items do NOT have to be instances of this class or its subclass.

If these settings are not defined or only part of namespaces are defined then other used namespaces will be declared either in the :code:<item> element or in its subelements when these namespaces are not unique. Each :code:<item> element and its sublements always contains only namespace declarations of non-:code:None attributes (including ones that are interpreted as element content).

Scrapy Project Examples

Examples directory <https://github.com/woxcab/scrapy_rss/blob/master/examples>_ contains several Scrapy projects with the scrapy_rss usage demonstration. It crawls this website <https://woxcab.github.io/scrapy_rss/>_ whose source code is here <https://github.com/woxcab/scrapy_rss/blob/master/examples/website>_.

Just go to the Scrapy project directory and run commands

.. code:: bash

scrapy crawl first_spider scrapy crawl second_spider

Thereafter feed.rss and feed2.rss files will be created in the same directory.