// Example: adaptive selectors that survive DOM changes.
//
// Adaptive selectors learn an element signature on first successful match.
// On future runs, even when the producer renames or restructures the
// containing CSS class, similarity matching falls back to the saved
// signature so the scraper keeps working without code changes.
//
// This example demonstrates the inline Response API on a static HTML
// fixture so it can be run without network access:
//
// - Run 1: original markup with class "product" — selector matches,
// signature is learned and persisted to ./adaptive_signatures.json
// - Run 2: same page but the class has been renamed to "item" —
// CSS selector finds nothing, but Response.Adaptive() falls back to
// the saved signature and still extracts the price
//
// Run:
//
// go run ./examples/adaptive/
package main
import (
"fmt"
"log"
"os"
foxhound "github.com/sadewadee/foxhound"
"github.com/sadewadee/foxhound/parse"
)
const originalHTML = `
Super Widget
$10
`
const renamedHTML = `
Super Widget
$10
`
func main() {
// Persist learned signatures across program runs. Pass "" for an
// in-memory only extractor.
storePath := "./adaptive_signatures.json"
defer os.Remove(storePath)
ae := parse.NewAdaptiveExtractor(storePath)
// --- Run 1: original markup, learn the signature ---
resp1 := &foxhound.Response{
Body: []byte(originalHTML),
URL: "https://shop.example/p/1",
}
resp1.SetAdaptiveExtractor(ae)
price1 := resp1.CSSAdaptive(".product", "price").Text()
fmt.Printf("run 1: CSSAdaptive(.product) = %q\n", price1)
if err := ae.Save(); err != nil {
log.Fatalf("save signatures: %v", err)
}
// --- Run 2: simulate a redesign — class renamed from .product to .item.
// The primary CSS selector finds nothing, but the learned signature
// resolves the same element via similarity matching.
resp2 := &foxhound.Response{
Body: []byte(renamedHTML),
URL: "https://shop.example/p/1",
}
resp2.SetAdaptiveExtractor(ae)
plain := resp2.CSS(".product").Text()
fmt.Printf("run 2: plain CSS(.product) = %q (selector broken)\n", plain)
adaptive := resp2.Adaptive("price")
fmt.Printf("run 2: Adaptive(price) = %q (recovered via signature)\n", adaptive)
if adaptive != "$10" {
log.Fatalf("expected $10, got %q", adaptive)
}
fmt.Println("ok: adaptive selector survived class rename")
}