Change Detection

1{
2    "field": "price",        # Changed field name
3    "old_value": "299.99",   # Previous baseline value
4    "new_value": "249.99",   # Current value
5    "change_type": "PriceChange",
6    "change_pct": -16.67,    # Percentage change (numeric fields)
7    "url": "https://example.com/product/1",
8    "timestamp": "2026-07-26T10:30:00Z"
9}

1from crawlingo import detect_changes
2
3old_data = {"price": "299.99", "title": "Widget"}
4new_data = {"price": "249.99", "title": "Widget"}
5
6changes = detect_changes("https://example.com", old_data, new_data)
7for change in changes:
8    print(f"{change.field}: {change.change_type} ({change.old_value} → {change.new_value})")

1import requests
2from crawlingo import Watch
3
4def on_change(event):
5    requests.post("https://my-api.example.com/webhook", json={
6        "field": event.field,
7        "old_value": event.old_value,
8        "new_value": event.new_value,
9        "change_type": event.event_type,
10        "url": event.url,
11    })
12
13Watch("https://example.com")\
14    .field("price", "span.price", extraction_type="price")\
15    .interval(300)\
16    .on_change(on_change)