able to parse xml

internal/entity/gooditem.go

@@ -45,15 +45,6 @@ type GoodsItemRaw struct {
 type MappedGoodsRemnants map[int]GoodsRemnant
 type GoodsRemnant [4]int32
 
-func ExtractProductIDs(items []GoodsItem) (out []int) {
-	out = make([]int, 0, len(items))
-	for _, item := range items {
-		out = append(out, int(item.Cart))
-	}
-
-	return out
-}
-
 func MakeGoodsItem(
 	gi GoodsItemRaw,
 	remnants MappedGoodsRemnants,

internal/entity/iter.go

@@ -0,0 +1,28 @@
+package entity
+
+func IterWithErr[T any](t []T, err error) iterWithErr[T] {
+	return iterWithErr[T]{
+		items: t,
+		err:   err,
+	}
+}
+
+type iterWithErr[T any] struct {
+	items []T
+	err   error
+}
+
+func (iter iterWithErr[T]) Do(f func(T) error) error {
+	if iter.err != nil {
+		return iter.err
+	}
+
+	for _, item := range iter.items {
+		err := f(item)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}