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docs/EXTRACTION_STRATEGIES.md
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# Content Extraction Strategies
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The crawler uses multiple strategies to dynamically extract article metadata from any website.
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## 🎯 What Gets Extracted
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1. **Title** - Article headline
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2. **Author** - Article writer/journalist
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3. **Published Date** - When article was published
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4. **Content** - Main article text
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5. **Description** - Meta description/summary
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## 📋 Extraction Strategies
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### 1. Title Extraction
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Tries multiple methods in order of reliability:
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#### Strategy 1: H1 Tag
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```html
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<h1>Article Title Here</h1>
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```
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✅ Most reliable - usually the main headline
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#### Strategy 2: Open Graph Meta Tag
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```html
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<meta property="og:title" content="Article Title Here" />
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```
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✅ Used by Facebook, very reliable
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#### Strategy 3: Twitter Card Meta Tag
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```html
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<meta name="twitter:title" content="Article Title Here" />
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```
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✅ Used by Twitter, reliable
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#### Strategy 4: Title Tag (Fallback)
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```html
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<title>Article Title | Site Name</title>
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```
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⚠️ Often includes site name, needs cleaning
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**Cleaning:**
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- Removes " | Site Name"
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- Removes " - Site Name"
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---
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### 2. Author Extraction
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Tries multiple methods:
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#### Strategy 1: Meta Author Tag
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```html
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<meta name="author" content="John Doe" />
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```
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✅ Standard HTML meta tag
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#### Strategy 2: Rel="author" Link
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```html
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<a rel="author" href="/author/john-doe">John Doe</a>
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```
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✅ Semantic HTML
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#### Strategy 3: Common Class Names
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```html
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<div class="author-name">John Doe</div>
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<span class="byline">By John Doe</span>
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<p class="writer">John Doe</p>
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```
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✅ Searches for: author-name, author, byline, writer
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#### Strategy 4: Schema.org Markup
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```html
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<span itemprop="author">John Doe</span>
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```
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✅ Structured data
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#### Strategy 5: JSON-LD Structured Data
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```html
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<script type="application/ld+json">
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{
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"@type": "NewsArticle",
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"author": {
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"@type": "Person",
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"name": "John Doe"
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}
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}
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</script>
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```
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✅ Most structured, very reliable
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**Cleaning:**
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- Removes "By " prefix
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- Validates length (< 100 chars)
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---
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### 3. Date Extraction
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Tries multiple methods:
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#### Strategy 1: Time Tag with Datetime
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```html
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<time datetime="2024-11-10T10:00:00Z">November 10, 2024</time>
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```
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✅ Most reliable - ISO format
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#### Strategy 2: Article Published Time Meta
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```html
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<meta property="article:published_time" content="2024-11-10T10:00:00Z" />
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```
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✅ Open Graph standard
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#### Strategy 3: OG Published Time
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```html
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<meta property="og:published_time" content="2024-11-10T10:00:00Z" />
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```
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✅ Facebook standard
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#### Strategy 4: Common Class Names
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```html
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<span class="publish-date">November 10, 2024</span>
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<time class="published">2024-11-10</time>
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<div class="timestamp">10:00 AM, Nov 10</div>
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```
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✅ Searches for: publish-date, published, date, timestamp
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#### Strategy 5: Schema.org Markup
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```html
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<meta itemprop="datePublished" content="2024-11-10T10:00:00Z" />
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```
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✅ Structured data
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#### Strategy 6: JSON-LD Structured Data
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```html
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<script type="application/ld+json">
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{
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"@type": "NewsArticle",
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"datePublished": "2024-11-10T10:00:00Z"
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}
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</script>
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```
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✅ Most structured
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---
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### 4. Content Extraction
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Tries multiple methods:
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#### Strategy 1: Semantic HTML Tags
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```html
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<article>
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<p>Article content here...</p>
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</article>
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```
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✅ Best practice HTML5
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#### Strategy 2: Common Class Names
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```html
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<div class="article-content">...</div>
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<div class="article-body">...</div>
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<div class="post-content">...</div>
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<div class="entry-content">...</div>
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<div class="story-body">...</div>
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```
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✅ Searches for common patterns
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#### Strategy 3: Schema.org Markup
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```html
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<div itemprop="articleBody">
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<p>Content here...</p>
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</div>
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```
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✅ Structured data
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#### Strategy 4: Main Tag
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```html
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<main>
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<p>Content here...</p>
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</main>
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```
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✅ Semantic HTML5
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#### Strategy 5: Body Tag (Fallback)
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```html
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<body>
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<p>Content here...</p>
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</body>
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```
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⚠️ Last resort, may include navigation
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**Content Filtering:**
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- Removes `<script>`, `<style>`, `<nav>`, `<footer>`, `<header>`, `<aside>`
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- Filters out short paragraphs (< 50 chars) - likely ads/navigation
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- Keeps only substantial paragraphs
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- **No length limit** - stores full article content
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---
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## 🔍 How It Works
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### Example: Crawling a News Article
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```python
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# 1. Fetch HTML
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response = requests.get(article_url)
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soup = BeautifulSoup(response.content, 'html.parser')
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# 2. Extract title (tries 4 strategies)
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title = extract_title(soup)
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# Result: "New U-Bahn Line Opens in Munich"
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# 3. Extract author (tries 5 strategies)
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author = extract_author(soup)
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# Result: "Max Mustermann"
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# 4. Extract date (tries 6 strategies)
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published_date = extract_date(soup)
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# Result: "2024-11-10T10:00:00Z"
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# 5. Extract content (tries 5 strategies)
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content = extract_main_content(soup)
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# Result: "The new U-Bahn line connecting..."
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# 6. Save to database
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article_doc = {
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'title': title,
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'author': author,
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'published_at': published_date,
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'full_content': content,
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'word_count': len(content.split())
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}
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```
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---
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## 📊 Success Rates by Strategy
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Based on common news sites:
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| Strategy | Success Rate | Notes |
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|----------|-------------|-------|
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| H1 for title | 95% | Almost universal |
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| OG meta tags | 90% | Most modern sites |
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| Time tag for date | 85% | HTML5 sites |
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| JSON-LD | 70% | Growing adoption |
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| Class name patterns | 60% | Varies by site |
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| Schema.org | 50% | Not widely adopted |
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---
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## 🎨 Real-World Examples
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### Example 1: Süddeutsche Zeitung
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```html
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<article>
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<h1>New U-Bahn Line Opens</h1>
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<span class="author">Max Mustermann</span>
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<time datetime="2024-11-10T10:00:00Z">10. November 2024</time>
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<div class="article-body">
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<p>The new U-Bahn line...</p>
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</div>
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</article>
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```
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✅ Extracts: Title (H1), Author (class), Date (time), Content (article-body)
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### Example 2: Medium Blog
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```html
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<article>
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<h1>How to Build a News Crawler</h1>
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<meta property="og:title" content="How to Build a News Crawler" />
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<meta property="article:published_time" content="2024-11-10T10:00:00Z" />
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<a rel="author" href="/author">Jane Smith</a>
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<section>
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<p>In this article...</p>
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</section>
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</article>
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```
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✅ Extracts: Title (OG meta), Author (rel), Date (article meta), Content (section)
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### Example 3: WordPress Blog
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```html
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<div class="post">
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<h1 class="entry-title">My Blog Post</h1>
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<span class="byline">By John Doe</span>
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<time class="published">November 10, 2024</time>
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<div class="entry-content">
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<p>Blog content here...</p>
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</div>
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</div>
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```
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✅ Extracts: Title (H1), Author (byline), Date (published), Content (entry-content)
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---
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## ⚠️ Edge Cases Handled
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1. **Missing Fields**: Returns `None` instead of crashing
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2. **Multiple Authors**: Takes first one found
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3. **Relative Dates**: Stores as-is ("2 hours ago")
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4. **Paywalls**: Extracts what's available
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5. **JavaScript-rendered**: Only gets server-side HTML
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6. **Ads/Navigation**: Filtered out by paragraph length
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7. **Site Name in Title**: Cleaned automatically
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---
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## 🚀 Future Improvements
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Potential enhancements:
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- [ ] JavaScript rendering (Selenium/Playwright)
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- [ ] Paywall bypass (where legal)
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- [ ] Image extraction
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- [ ] Video detection
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- [ ] Related articles
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- [ ] Tags/categories
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- [ ] Reading time estimation
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- [ ] Language detection
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- [ ] Sentiment analysis
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---
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## 🧪 Testing
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Test the extraction on a specific URL:
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```python
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from crawler_service import extract_article_content
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url = "https://www.sueddeutsche.de/muenchen/article-123"
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data = extract_article_content(url)
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print(f"Title: {data['title']}")
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print(f"Author: {data['author']}")
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print(f"Date: {data['published_date']}")
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print(f"Content length: {len(data['content'])} chars")
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print(f"Word count: {data['word_count']}")
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```
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---
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## 📚 Standards Supported
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- ✅ HTML5 semantic tags
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- ✅ Open Graph Protocol
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- ✅ Twitter Cards
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- ✅ Schema.org microdata
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- ✅ JSON-LD structured data
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- ✅ Dublin Core metadata
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- ✅ Common CSS class patterns
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