Added int32 type.

int32.go

@@ -0,0 +1,55 @@
+package null
+
+import (
+	"database/sql"
+	"encoding/json"
+)
+
+// Int32 is a nullable int32 type based on sql.NullInt32, that supports parsing to/from JSON.
+type Int32 struct {
+	sql.NullInt32
+}
+
+// NewInt32 returns a new nullable Int32 object.
+// This is equivalent to `null.Int32{sql.NullInt32{Int32: i, Valid: valid}}`.
+func NewInt32(i int32, valid bool) Int32 {
+	return Int32{sql.NullInt32{Int32: i, Valid: valid}}
+}
+
+// MarshalJSON implements the encoding json interface.
+func (i Int32) MarshalJSON() ([]byte, error) {
+	if i.Valid {
+		return json.Marshal(i.Int32)
+	}
+
+	return json.Marshal(nil)
+}
+
+// UnmarshalJSON implements the encoding json interface.
+func (i *Int32) UnmarshalJSON(data []byte) error {
+	var value *int32
+
+	if err := json.Unmarshal(data, &value); err != nil {
+		return err
+	}
+
+	if value != nil {
+		i.SetValid(*value)
+	} else {
+		i.SetNil()
+	}
+
+	return nil
+}
+
+// SetValid sets the value and valid to true.
+func (i *Int32) SetValid(value int32) {
+	i.Int32 = value
+	i.Valid = true
+}
+
+// SetNil sets the value to default and valid to false.
+func (i *Int32) SetNil() {
+	i.Int32 = 0
+	i.Valid = false
+}

int32_test.go

@@ -0,0 +1,71 @@
+package null
+
+import (
+	"database/sql"
+	"encoding/json"
+	"testing"
+)
+
+type testInt32 struct {
+	Value Int32 `json:"value"`
+}
+
+func TestNewInt32(t *testing.T) {
+	value := NewInt32(123, true)
+
+	if value.Int32 != 123 || !value.Valid {
+		t.Fatal("New Int32 must have value and be valid")
+	}
+}
+
+func TestMarshalInt32(t *testing.T) {
+	value := Int32{sql.NullInt32{Int32: 123, Valid: true}}
+
+	if data, err := json.Marshal(value); err != nil || string(data) != "123" {
+		t.Fatalf("Int32 must be marshalled to value, but was %v %v", err, string(data))
+	}
+
+	value.Valid = false
+
+	if data, err := json.Marshal(value); err != nil || string(data) != "null" {
+		t.Fatalf("Int32 must be marshalled to null, but was %v %v", err, string(data))
+	}
+}
+
+func TestUnmarshalInt32(t *testing.T) {
+	str := `{"value": 123}`
+	var value testInt32
+
+	if err := json.Unmarshal([]byte(str), &value); err != nil {
+		t.Fatalf("Int32 must be unmarshalled to value, but was %v", err)
+	}
+
+	if !value.Value.Valid || value.Value.Int32 != 123 {
+		t.Fatalf("Unmarshalled null Int32 must be valid, but was %v", value.Value)
+	}
+
+	str = `{"value": null}`
+
+	if err := json.Unmarshal([]byte(str), &value); err != nil {
+		t.Fatalf("Int32 must be unmarshalled to null, but was %v", err)
+	}
+
+	if value.Value.Valid {
+		t.Fatal("Unmarshalled null Int32 must be invalid")
+	}
+}
+
+func TestGettersSettersInt32(t *testing.T) {
+	value := NewInt32(123, true)
+	value.SetNil()
+
+	if value.Int32 != 0 || value.Valid {
+		t.Fatal("Int32 must be nil")
+	}
+
+	value.SetValid(123)
+
+	if value.Int32 != 123 || !value.Valid {
+		t.Fatal("Int32 must be valid")
+	}
+}