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Item

item is mainly used to define data model and extract data from HTML source code. It has the following two methods:

  • get_item: extract one data from HTML source code
  • get_items: extract many data from HTML source code

Core arguments

get_item and get_items receives same arguments: - html: optional, HTML source code - url: optional, HTML href link - html_etree: optional, etree._Element object

Usage

From the arguments above, we can see that, there are three ways to feed Item object: from a web link, from HTML source code, or even from etree._Element object.

import asyncio

from ruia import AttrField, TextField, Item

class HackerNewsItem(Item):
    target_item = TextField(css_select='tr.athing')
    title = TextField(css_select='a.storylink')
    url = AttrField(css_select='a.storylink', attr='href')

    async def clean_title(self, value):
        return value

async def main():
    async for item in HackerNewsItem.get_items(url="https://news.ycombinator.com/"):
        print(item.title, item.url)

if __name__ == '__main__':
     items = asyncio.run(main())

Sometimes we may come across such a condition. When crawling github issues, we will find that there are several tags to a issue. Define TagItem as a standalone item is not that beautiful. It's time to focus on the many=True argument. Fields with many=True will return a list.

from ruia import Item, TextField

class GithiubIssueItem(Item):
    issue_id = TextField(css_select='issue_id_class')
    title = TextField(css_select='issue_title_class')
    tags = TextField(css_select='tag_class',many=True)


item = GithiubIssueItem.get_item(html)
assert isinstance(item.tags, list)

AttrField also has the argument many.

How It Works?

Inner, item class will change different kinds of inputs into etree._Element obejct, and then extract data. Meta class will help to get every property defined by Filed.