support datafields in projection

catalog/builder.go

@@ -115,6 +115,23 @@ func Apply(s Schema, source map[string]any) (Projection, error) {
 		truthy = DefaultTrueValues()
 	}
 
+	var attrs json.RawMessage
+	if len(s.AttributesFields) > 0 {
+		m := make(map[string]any)
+		for _, key := range s.AttributesFields {
+			if val, ok := source[key]; ok && val != nil {
+				m[key] = val
+			}
+		}
+		if len(m) > 0 {
+			b, err := json.Marshal(m)
+			if err != nil {
+				return Projection{}, fmt.Errorf("%w: marshal attributes: %w", ErrProjectionBuild, err)
+			}
+			attrs = b
+		}
+	}
+
 	p := Projection{
 		ItemID:           uint32Of(source, s.ItemIdField),
 		ID:               id,
@@ -122,6 +139,7 @@ func Apply(s Schema, source map[string]any) (Projection, error) {
 		Title:            stringOf(source, s.TitleField),
 		PriceIncVat:      price,
 		Currency:         cur,
+		Attributes:       attrs,
 		TaxClass:         tax,
 		InventoryTracked: boolOf(source, s.InventoryTrackedF, truthy),
 		DropShip:         boolOf(source, s.DropShipF, truthy),

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.)

catalog/projection.go

@@ -92,13 +92,14 @@ type Projection struct {
 	// TaxClass uses a string identifier (see platform/tax class constants).
 	// Empty string means "unclassified"; the consumer's tax.Provider is what
 	// resolves the identifier to a numeric rate.
-	TaxClass         string `json:"tax_class"`
+	Attributes       json.RawMessage `json:"attributes,omitempty"`
-	InventoryTracked bool   `json:"inventory_tracked"`
+	TaxClass         string          `json:"tax_class"`
-	DropShip         bool   `json:"drop_ship"`
+	InventoryTracked bool            `json:"inventory_tracked"`
-	Category         string `json:"category,omitempty"`
+	DropShip         bool            `json:"drop_ship"`
-	Brand            string `json:"brand,omitempty"`
+	Category         string          `json:"category,omitempty"`
-	Image            string `json:"image,omitempty"`
+	Brand            string          `json:"brand,omitempty"`
-	UpdatedAt        int64  `json:"updated_at"`
+	Image            string          `json:"image,omitempty"`
+	UpdatedAt        int64           `json:"updated_at"`
 }
 
 // PayloadKey is the envelope key producers use when publishing a slice of

catalog/schema.go

@@ -61,6 +61,9 @@ type Schema struct {
 	CategoryField     string `json:"category_field,omitempty"`
 	BrandField        string `json:"brand_field,omitempty"`
 	ImageField        string `json:"image_field,omitempty"`
+	// AttributesFields names the keys in the source map[string]any that
+	// should be extracted and built into the Projection's json.RawMessage Attributes field.
+	AttributesFields []string `json:"attributes_fields,omitempty"`
 	// ItemIdField is the source-side key carrying the producer's catalog
 	// item id (uint32-equivalent). DefaultSchema points at "id" (matching
 	// the product service's /api/get/{sku} shape). Producers that omit
@@ -127,6 +130,7 @@ func DefaultSchema() Schema {
 		// Standard product service carries the integer catalog id under "id".
 		ItemIdField:      "id",
 		UpdatedAtField:    "updated_at",
+		AttributesFields: []string{"data"},
 
 		FixedCurrency:    "",     // read from source if present
 		DefaultTaxClass:  "standard",
@@ -165,6 +169,7 @@ func BygglagretSchema() Schema {
 		ImageField:       "PrimaryImage",
 		ItemIdField:      "item_id",
 		UpdatedAtField:   "LastModifiedMs",
+		AttributesFields: []string{"data"},
 
 		FixedCurrency:    "SEK",
 		DefaultTaxClass:  "standard",