Add IsZero method to all Null types to support omitzero

bool.go

@@ -39,3 +39,7 @@ func (n *NullBool) Scan(src any) error {
 	n.Valid = reflect.TypeOf(src) != nil
 	return nil
 }
+
+func (n *NullBool) IsZero() bool {
+	return !n.Valid
+}

byte.go

@@ -39,3 +39,7 @@ func (n *NullByte) Scan(src any) error {
 	n.Valid = reflect.TypeOf(src) != nil
 	return nil
 }
+
+func (n *NullByte) IsZero() bool {
+	return !n.Valid
+}

float64.go

@@ -39,3 +39,7 @@ func (n *NullFloat64) Scan(src any) error {
 	n.Valid = reflect.TypeOf(src) != nil
 	return nil
 }
+
+func (n *NullFloat64) IsZero() bool {
+	return !n.Valid
+}

generic.go

@@ -40,3 +40,7 @@ func (n *Null[T]) Scan(src any) error {
 	n.Valid = reflect.TypeOf(src) != nil
 	return nil
 }
+
+func (n *Null[T]) IsZero() bool {
+	return !n.Valid
+}

go.mod

@@ -1,6 +1,6 @@
 module github.com/gkits/sqlnull
 
-go 1.23.2
+go 1.24
 
 require (
 	github.com/mattn/go-sqlite3 v1.14.24

int16.go

@@ -39,3 +39,7 @@ func (n *NullInt16) Scan(src any) error {
 	n.Valid = reflect.TypeOf(src) != nil
 	return nil
 }
+
+func (n *NullInt16) IsZero() bool {
+	return !n.Valid
+}

int32.go

@@ -39,3 +39,7 @@ func (n *NullInt32) Scan(src any) error {
 	n.Valid = reflect.TypeOf(src) != nil
 	return nil
 }
+
+func (n *NullInt32) IsZero() bool {
+	return !n.Valid
+}

int64.go

@@ -39,3 +39,7 @@ func (n *NullInt64) Scan(src any) error {
 	n.Valid = reflect.TypeOf(src) != nil
 	return nil
 }
+
+func (n *NullInt64) IsZero() bool {
+	return !n.Valid
+}

sqlnull_test.go

@@ -24,6 +24,18 @@ type target struct {
 	Time    sqlnull.NullTime     `json:"time"`
 }
 
+type targetOmitZero struct {
+	Generic sqlnull.Null[string] `json:"generic,omitzero"`
+	String  sqlnull.NullString   `json:"string,omitzero"`
+	Bool    sqlnull.NullBool     `json:"bool,omitzero"`
+	Byte    sqlnull.NullByte     `json:"byte,omitzero"`
+	Int16   sqlnull.NullInt16    `json:"int16,omitzero"`
+	Int32   sqlnull.NullInt32    `json:"int32,omitzero"`
+	Int64   sqlnull.NullInt64    `json:"int64,omitzero"`
+	Float64 sqlnull.NullFloat64  `json:"float64,omitzero"`
+	Time    sqlnull.NullTime     `json:"time,omitzero"`
+}
+
 func Test_MarshalJSON(t *testing.T) {
 	cases := []struct {
 		name string
@@ -98,7 +110,7 @@ func Test_UnmarshalJSON(t *testing.T) {
 		want target
 	}{
 		{
-			name: "successfully marshal with values",
+			name: "successfully unmarshal with values",
 			in: []byte(`{ 
                 "generic": "generic", 
                 "string": "string",
@@ -123,7 +135,7 @@ func Test_UnmarshalJSON(t *testing.T) {
 			},
 		},
 		{
-			name: "successfully marshal with null",
+			name: "successfully unmarshal with null",
 			in: []byte(`{ 
                 "generic": null,
                 "string": null,
@@ -147,6 +159,21 @@ func Test_UnmarshalJSON(t *testing.T) {
 				Time:    sqlnull.NullTime{Time: time.Time{}, Valid: false},
 			},
 		},
+		{
+			name: "successfully unmarshal with empty json",
+			in:   []byte(`{}`),
+			want: target{
+				Generic: sqlnull.Null[string]{V: "", Valid: false},
+				String:  sqlnull.NullString{String: "", Valid: false},
+				Bool:    sqlnull.NullBool{Bool: false, Valid: false},
+				Byte:    sqlnull.NullByte{Byte: 0, Valid: false},
+				Int16:   sqlnull.NullInt16{Int16: 0, Valid: false},
+				Int32:   sqlnull.NullInt32{Int32: 0, Valid: false},
+				Int64:   sqlnull.NullInt64{Int64: 0, Valid: false},
+				Float64: sqlnull.NullFloat64{Float64: 0, Valid: false},
+				Time:    sqlnull.NullTime{Time: time.Time{}, Valid: false},
+			},
+		},
 	}
 
 	for _, c := range cases {
@@ -244,3 +271,61 @@ func Test_Scan(t *testing.T) {
 		})
 	}
 }
+
+func Test_MarshalJSONOmitZero(t *testing.T) {
+	cases := []struct {
+		name string
+		in   targetOmitZero
+		want string
+	}{
+		{
+			name: "successfully marshal with values",
+			in: targetOmitZero{
+				Generic: sqlnull.Null[string]{V: "generic", Valid: true},
+				String:  sqlnull.NullString{String: "string", Valid: true},
+				Bool:    sqlnull.NullBool{Bool: true, Valid: true},
+				Byte:    sqlnull.NullByte{Byte: 255, Valid: true},
+				Int16:   sqlnull.NullInt16{Int16: 16, Valid: true},
+				Int32:   sqlnull.NullInt32{Int32: 32, Valid: true},
+				Int64:   sqlnull.NullInt64{Int64: 64, Valid: true},
+				Float64: sqlnull.NullFloat64{Float64: 64.6464, Valid: true},
+				Time:    sqlnull.NullTime{Time: time.Date(2024, 10, 23, 17, 50, 0, 0, time.UTC), Valid: true},
+			},
+			want: `{ 
+                "generic": "generic",
+                "string": "string",
+                "bool": true,
+                "byte": 255,
+                "int16": 16,
+                "int32": 32,
+                "int64": 64,
+                "float64": 64.6464,
+                "time": "2024-10-23T17:50:00Z"
+            }`,
+		},
+		{
+			name: "successfully marshal empty json",
+			in: targetOmitZero{
+				Generic: sqlnull.Null[string]{V: "generic", Valid: false},
+				String:  sqlnull.NullString{String: "string", Valid: false},
+				Bool:    sqlnull.NullBool{Bool: true, Valid: false},
+				Byte:    sqlnull.NullByte{Byte: 255, Valid: false},
+				Int16:   sqlnull.NullInt16{Int16: 16, Valid: false},
+				Int32:   sqlnull.NullInt32{Int32: 32, Valid: false},
+				Int64:   sqlnull.NullInt64{Int64: 64, Valid: false},
+				Float64: sqlnull.NullFloat64{Float64: 64.6464, Valid: false},
+				Time:    sqlnull.NullTime{Time: time.Date(2024, 10, 23, 17, 50, 0, 0, time.UTC), Valid: false},
+			},
+			want: `{}`,
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			got, err := json.Marshal(c.in)
+			t.Log(string(got))
+			require.NoError(t, err)
+			assert.JSONEq(t, c.want, string(got))
+		})
+	}
+}

string.go

@@ -39,3 +39,7 @@ func (n *NullString) Scan(src any) error {
 	n.Valid = reflect.TypeOf(src) != nil
 	return nil
 }
+
+func (n *NullString) IsZero() bool {
+	return !n.Valid
+}

time.go

@@ -40,3 +40,7 @@ func (n *NullTime) Scan(src any) error {
 	n.Valid = reflect.TypeOf(src) != nil
 	return nil
 }
+
+func (n *NullTime) IsZero() bool {
+	return !n.Valid
+}