support datafields in projection

catalog/builder_test.go

@@ -37,6 +37,39 @@ func TestBuilderJSONNumber(t *testing.T) {
 	}
 }
 
+func TestBuilderAttributes(t *testing.T) {
+	s := DefaultSchema()
+	s.AttributesFields = []string{"cart", "color"}
+	src := map[string]any{
+		"sku":           "X-1",
+		"price_inc_vat": int64(100),
+		"updated_at":    int64(1700000000000),
+		"cart":          map[string]any{"data": "some-cart-data"},
+		"color":         "red",
+		"ignored":       "should-not-be-in-attrs",
+	}
+	p, err := Apply(s, src)
+	if err != nil {
+		t.Fatalf("Apply: %v", err)
+	}
+	var m map[string]any
+	if err := json.Unmarshal(p.Attributes, &m); err != nil {
+		t.Fatalf("unmarshal Attributes: %v", err)
+	}
+	if len(m) != 2 {
+		t.Errorf("expected 2 attributes, got %d", len(m))
+	}
+	if cartVal, ok := m["cart"].(map[string]any); !ok || cartVal["data"] != "some-cart-data" {
+		t.Errorf("cart attribute: got %v", m["cart"])
+	}
+	if m["color"] != "red" {
+		t.Errorf("color attribute: got %v", m["color"])
+	}
+	if _, ok := m["ignored"]; ok {
+		t.Errorf("ignored attribute was extracted: %v", m)
+	}
+}
+
 // Updated=UseSourceField: missing source updated_at MUST be a loud error,
 // not a stamp-now fallback. (Foot-gun 3 resolution: silence here invalidates
 // every consumer's cache on rebuild.)