fix: handle embedded structs in parser traversal

cache.go

@@ -30,17 +30,50 @@ func getStructCache(rt reflect.Type) *structInfo {
 
 	// Build struct info
 	info := &structInfo{name: rt.Name()}
+
+	// struct fields traversal
 	for i := 0; i < rt.NumField(); i++ {
 		field := rt.Field(i)
+
 		tag := field.Tag.Get("qp")
 
+		fieldType := field.Type
+		if fieldType.Kind() == reflect.Ptr {
+			fieldType = fieldType.Elem()
+		}
+
+		isStruct := fieldType.Kind() == reflect.Struct && fieldType != reflect.TypeFor[time.Time]()
+
+		// traverse embedded structs
+		if field.Anonymous && isStruct {
+			info.fields = append(info.fields, fieldInfo{
+				name:     field.Name,
+				typ:      field.Type,
+				index:    field.Index,
+				isNested: true,
+			})
+			continue
+		}
+
 		if !field.IsExported() {
 			if tag != "" {
 				info.hasUnexportedWithTag = true
 			}
 			continue
 		}
 
+		// tag on struct will be ignored
+		if isStruct {
+			info.fields = append(info.fields, fieldInfo{
+				name:     field.Name,
+				typ:      field.Type,
+				index:    field.Index,
+				isNested: true,
+			})
+			continue
+		}
+
+		// leaf field
 		if tag != "" {
 			info.fields = append(info.fields, fieldInfo{
 				name:     field.Name,
@@ -49,22 +82,8 @@ func getStructCache(rt reflect.Type) *structInfo {
 				index:    field.Index,
 				isNested: false,
 			})
-		} else {
-			// Check if this field is a nested struct (struct or pointer to struct)
-			fieldType := field.Type
-			if fieldType.Kind() == reflect.Ptr {
-				fieldType = fieldType.Elem()
-			}
-			if fieldType.Kind() == reflect.Struct && fieldType != reflect.TypeOf(time.Time{}) {
-				info.fields = append(info.fields, fieldInfo{
-					name:     field.Name,
-					tag:      "",
-					typ:      field.Type, // Keep the original type (may be pointer)
-					index:    field.Index,
-					isNested: true,
-				})
-			}
 		}
+
 	}
 
 	// LoadOrStore handles race conditions atomically

parser_test.go

@@ -738,6 +738,50 @@ func TestNestedStruct(t *testing.T) {
 		err = Parse(values, &s)
 		assert.Error(t, err)
 	})
+
+	t.Run("Embedded/Anonymous-Nested-Struct", func(t *testing.T) {
+		type filter1 struct {
+			Foo []string `qp:"foo"`
+		}
+
+		type filter2 struct {
+			filter1
+			Bar []string `qp:"bar"`
+		}
+
+		type sortOrder struct {
+			By  string `qp:"sort_by"`
+			Dir string `qp:"sort_dir"`
+		}
+
+		type input struct {
+			Filter filter2
+			Sort   sortOrder
+		}
+
+		var in input
+		queryParams := "foo=f1&bar=b1,b2&sort_by=foo&sort_dir=desc"
+		expected := input{
+			Filter: filter2{
+				filter1: filter1{
+					Foo: []string{"f1"},
+				},
+				Bar: []string{"b1", "b2"},
+			},
+			Sort: sortOrder{
+				By:  "foo",
+				Dir: "desc",
+			},
+		}
+
+		values, err := url.ParseQuery(queryParams)
+		require.NoError(t, err)
+
+		err = Parse(values, &in)
+		require.NoError(t, err)
+
+		assert.Equal(t, in, expected)
+	})
 }
 
 func ptr[T any](v T) *T {