RomanNum3ral
/
scrapy
mirror of https://github.com/scrapy/scrapy.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #4652 from elacuesta/docs-loaders-dataclass 

Docs: Simplify dataclass example in item loader page
This commit is contained in:
Andrey Rahmatullin 2020-07-01 17:35:33 +05:00 committed by GitHub
parent e46b47c365 5b88c522ac
commit 0379df8608
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 6 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
docs/topics/loaders.rst
View File

@ -88,29 +88,17 @@ item loaders: unless a pre-populated item is passed to the loader, fields
will be populated incrementally using the loader's :meth:`~ItemLoader.add_xpath`,
:meth:`~ItemLoader.add_css` and :meth:`~ItemLoader.add_value` methods.
Given the way that item loaders store data internally, one approach
to overcome this is to define items using the :func:`~dataclasses.field`
function, with ``list`` as the ``default_factory`` argument::
One approach to overcome this is to define items using the
:func:`~dataclasses.field` function, with a ``default`` argument::
from dataclasses import dataclass, field
from typing import Optional
@dataclass
class InventoryItem:
name: str = field(default_factory=list)
price: float = field(default_factory=list)
stock: int = field(default_factory=list)
Note that in order to keep the example simple, the types do not match
completely. A more accurate but verbose definition would be::
from dataclasses import dataclass, field
from typing import List, Union
@dataclass
class InventoryItem:
name: Union[str, List[str]] = field(default_factory=list)
price: Union[float, List[float]] = field(default_factory=list)
stock: Union[int, List[int]] = field(default_factory=list)
name: Optional[str] = field(default=None)
price: Optional[float] = field(default=None)
stock: Optional[int] = field(default=None)
.. _topics-loaders-processors: