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dataflowkitvsdude

BSD-3-Clause 4 3 636
Feb 09 2017 2024-02-01(19 days ago)
400 2 26 MIT
0.1.3(6 months ago) Feb 20 2022 47 (month)

Dataflow kit ("DFK") is a Web Scraping framework for Gophers. It extracts data from web pages, following the specified CSS Selectors. You can use it in many ways for data mining, data processing or archiving.

Web-scraping pipeline consists of 3 general components:

  • Downloading an HTML web-page. (Fetch Service)
  • Parsing an HTML page and retrieving data we're interested in (Parse Service)
  • Encoding parsed data to CSV, MS Excel, JSON, JSON Lines or XML format.

For fetching dataflowkit has several types of page fetchers:

  • Base fetcher uses standard golang http client to fetch pages as is. It works faster than Chrome fetcher. But Base fetcher cannot render dynamic javascript driven web pages.
  • Chrome fetcher is intended for rendering dynamic javascript based content. It sends requests to Chrome running in headless mode.

For parsing dataflowkit extracts data from downloaded web page following the rules listed in configuration JSON file. Extracted data is returned in CSV, MS Excel, JSON or XML format.

Some dataflowkit features:

  • Scraping of JavaScript generated pages;
  • Data extraction from paginated websites;
  • Processing infinite scrolled pages.
  • S—Āraping of websites behind login form;
  • Cookies and sessions handling;
  • Following links and detailed pages processing;
  • Managing delays between requests per domain;
  • Following robots.txt directives;
  • Saving intermediate data in Diskv or Mongodb. Storage interface is flexible enough to add more storage types easily;
  • Encode results to CSV, MS Excel, JSON(Lines), XML formats;
  • Dataflow kit is fast. It takes about 4-6 seconds to fetch and then parse 50 pages.
  • Dataflow kit is suitable to process quite large volumes of data. Our tests show the time needed to parse appr. 4 millions of pages is about 7 hours.

Dude (dude uncomplicated data extraction) is a very simple framework for writing web scrapers using Python decorators. The design, inspired by Flask, was to easily build a web scraper in just a few lines of code. Dude has an easy-to-learn syntax.

The simplest web scraper will look like this:

from dude import select


@select(css="a")
def get_link(element):
    return {"url": element.get_attribute("href")}

dude supports multiple parser backends: - playwright
- lxml
- parsel - beautifulsoup - pyppeteer - selenium

Example Use


Dataflowkit uses JSON configuration like:
{
  "name": "collection",
  "request": {
      "url": "https://example.com"
  },
  "fields": [
      {
          "name": "Title",
          "selector": ".product-container a",
          "extractor": {
              "types": [
                  "text",
                  "href"
              ],
              "filters": [
                  "trim",
                  "lowerCase"
              ],
              "params": {
                  "includeIfEmpty": false
              }
          }
      },
      {
          "name": "Image",
          "selector": "#product-container img",
          "extractor": {
              "types": [
                  "alt",
                  "src",
                  "width",
                  "height"
              ],
              "filters": [
                  "trim",
                  "upperCase"
              ]
          }
      },
      {
          "name": "Buyinfo",
          "selector": ".buy-info",
          "extractor": {
              "types": [
                  "text"
              ],
              "params": {
                  "includeIfEmpty": false
              }
          }
      }
  ],
  "paginator": {
      "selector": ".next",
      "attr": "href",
      "maxPages": 3
  },
  "format": "json",
  "fetcherType": "chrome",
  "paginateResults": false
}
which is then ingested through CLI command.
from dude import select

"""
This example demonstrates how to use Parsel + async HTTPX
To access an attribute, use:
    selector.attrib["href"]
You can also access an attribute using the ::attr(name) pseudo-element, for example "a::attr(href)", then:
    selector.get()
To get the text, use ::text pseudo-element, then:
    selector.get()
"""


@select(css="a.url", priority=2)
async def result_url(selector):
    return {"url": selector.attrib["href"]}


# Option to get url using ::attr(name) pseudo-element
@select(css="a.url::attr(href)", priority=2)
async def result_url2(selector):
    return {"url2": selector.get()}


@select(css=".title::text", priority=1)
async def result_title(selector):
    return {"title": selector.get()}


@select(css=".description::text", priority=0)
async def result_description(selector):
    return {"description": selector.get()}


if __name__ == "__main__":
    import dude

    dude.run(urls=["https://dude.ron.sh"], parser="parsel")

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