structured data extraction from web pages

Structured data extraction from web pages means turning information on a webpage into organized fields you can store, search, analyze, or feed into another system.

Common approaches

1. Direct HTML parsing

   • Extract content from the DOM using CSS selectors or XPath.
   • Best when page structure is stable.

2. Embedded structured data

   • Many pages include:
     • JSON-LD
     • Microdata
     • RDFa
   • Often the cleanest source for things like products, articles, events, recipes.

3. Browser automation / rendering

   • Use Playwright, Puppeteer, Selenium, etc. to handle JavaScript-rendered pages.
   • Needed when content is loaded dynamically.

4. Text + LLM-based extraction

   • Convert page content to text and ask a model to extract fields into a schema.
   • Useful for messy or inconsistent pages, but less deterministic.

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Typical pipeline

1. Fetch page
2. Render if needed
3. Detect and parse structured data
4. Fall back to DOM extraction
5. Normalize fields
6. Validate against a schema
7. Store in JSON / database / CSV

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Example schema

{
  "title": "",
  "author": "",
  "published_date": "",
  "price": "",
  "currency": "",
  "availability": "",
  "url": ""
}

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Tools often used

• Python: BeautifulSoup, lxml, requests, Scrapy, Playwright
• JavaScript/TypeScript: Cheerio, Playwright, Puppeteer
• Structured data parsers: extruct, schema.org parsers
• Validation: Pydantic, JSON Schema

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Example: extracting JSON-LD in Python

import requests
from bs4 import BeautifulSoup
import json

html = requests.get("https://example.com").text
soup = BeautifulSoup(html, "html.parser")

for script in soup.find_all("script", type="application/ld+json"):
    try:
        data = json.loads(script.string)
        print(data)
    except Exception:
        pass

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Best practices

• Prefer structured data already present on the page
• Validate extracted values
• Handle pagination and duplicate records
• Respect robots.txt and site terms
• Add retries, timeouts, and rate limiting
• Log extraction failures for debugging

If you want, I can also provide:

• a complete Python scraper template
• a Playwright-based extractor
• or help design an extraction schema for your use case.