util/reflect: add IsZero helper

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

util/reflect/reflect.go

@@ -65,9 +65,26 @@ func IsEmpty(v reflect.Value) bool {
 		return v.IsNil()
 	case reflect.Invalid:
 		return true
-	}
+	case reflect.Struct:
+		var ok bool
+		for i := 0; i < v.NumField(); i++ {
+			ok = IsEmpty(v.FieldByIndex([]int{i}))
+			if !ok {
 				return false
 			}
+		}
+	default:
+		fmt.Printf("%#+v\n", v)
+		return false
+	}
+	return true
+}
+
+// IsZero returns true if struct is zero (not have any defined values)
+func IsZero(src interface{}) bool {
+	v := reflect.ValueOf(src)
+	return IsEmpty(v)
+}
 
 // Zero creates new zero interface
 func Zero(src interface{}) (interface{}, error) {

util/reflect/reflect_test.go

@@ -43,3 +43,50 @@ func TestURLVars(t *testing.T) {
 	}
 	_ = mp
 }
+
+func TestIsZero(t *testing.T) {
+	testStr1 := struct {
+		Name   string
+		Value  string
+		Nested struct {
+			NestedName string
+		}
+	}{
+		Name:  "test_name",
+		Value: "test_value",
+	}
+	testStr1.Nested.NestedName = "nested_name"
+
+	if ok := IsZero(testStr1); ok {
+		t.Fatalf("zero ret on non zero struct: %#+v", testStr1)
+	}
+
+	testStr1.Name = ""
+	testStr1.Value = ""
+	testStr1.Nested.NestedName = ""
+	if ok := IsZero(testStr1); !ok {
+		t.Fatalf("non zero ret on zero struct: %#+v", testStr1)
+	}
+
+	type testStr3 struct {
+		Nested string
+	}
+	type testStr2 struct {
+		Name   string
+		Nested *testStr3
+	}
+	vtest := &testStr2{
+		Name:   "test_name",
+		Nested: &testStr3{Nested: "nested_name"},
+	}
+	if ok := IsZero(vtest); ok {
+		t.Fatalf("zero ret on non zero struct: %#+v", vtest)
+	}
+	vtest.Nested = nil
+	vtest.Name = ""
+	if ok := IsZero(vtest); !ok {
+		t.Fatalf("non zero ret on zero struct: %#+v", vtest)
+	}
+
+	//t.Logf("XX %#+v\n", ok)
+}