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Update docstring for Item class

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Eugenio Lacuesta 2020-05-11 13:20:06 -03:00
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scrapy/item.py
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@ -138,18 +138,20 @@ class Item(DictItem, metaclass=ItemMeta):
"""
Base class for scraped items.
In Scrapy, an object is considered an *item* if it is an instance of either
:class:`Item` or :class:`dict`. For example, when the output of a
In Scrapy, an object is considered an ``item`` if it is an instance of either
:class:`Item` or :class:`dict`, or any subclass. For example, when the output of a
spider callback is evaluated, only instances of :class:`Item` or
:class:`dict` are passed to :ref:`item pipelines <topics-item-pipeline>`.
If you need instances of a custom class to be considered items by Scrapy,
you must inherit from either :class:`Item` or :class:`dict`.
Items offer the ability to declare :class:`Field` attributes, which can be
used to define metadata and control the way data is processed internally.
Please refer to the :ref:`documentation about fields <topics-items-fields>`
for additional information.
Items must declare :class:`Field` attributes, which are processed and stored
in the ``fields`` attribute. This restricts the set of allowed field names
and prevents typos, raising ``KeyError`` when referring to undefined fields.
Additionally, fields can be used to define metadata and control the way
data is processed internally. Please refer to the :ref:`documentation
about fields <topics-items-fields>` for additional information.
Unlike instances of :class:`dict`, instances of :class:`Item` may be
:ref:`tracked <topics-leaks-trackrefs>` to debug memory leaks.