json Marshaller interface for Inet

Note that this does allow the serialization/deserialization between
empty string and a Null struct. It does NOT permit invalid addresses or masks.

See #79

Author: Joe Atzberger

inet.go

@@ -3,6 +3,7 @@ package pgtype
 import (
 	"database/sql/driver"
 	"net"
+	"strings"
 
 	errors "golang.org/x/xerrors"
 )
@@ -122,7 +123,7 @@ func (src *Inet) AssignTo(dst interface{}) error {
 	return errors.Errorf("cannot decode %#v into %T", src, dst)
 }
 
-func (dst *Inet) DecodeText(ci *ConnInfo, src []byte) error {
+func (dst *Inet) DecodeText(_ *ConnInfo, src []byte) error {
 	if src == nil {
 		*dst = Inet{Status: Null}
 		return nil
@@ -150,7 +151,7 @@ func (dst *Inet) DecodeText(ci *ConnInfo, src []byte) error {
 	return nil
 }
 
-func (dst *Inet) DecodeBinary(ci *ConnInfo, src []byte) error {
+func (dst *Inet) DecodeBinary(_ *ConnInfo, src []byte) error {
 	if src == nil {
 		*dst = Inet{Status: Null}
 		return nil
@@ -218,6 +219,27 @@ func (src Inet) EncodeBinary(ci *ConnInfo, buf []byte) ([]byte, error) {
 	return append(buf, src.IPNet.IP...), nil
 }
 
+// MarshalJSON implements the json.Marshaler interface
+func (src Inet) MarshalJSON() ([]byte, error) {
+	if src.Status != Present {
+		return []byte(`""`), nil
+	}
+	v, err := src.Value()
+	if err != nil || v == nil {
+		return []byte(`""`), err
+	}
+	return []byte(`"` + v.(string) + `"`), nil
+}
+
+// UnmarshalJSON implements the json.Marshaler interface
+func (dst *Inet) UnmarshalJSON(data []byte) error {
+	trimmed := strings.Trim(string(data), `"`)
+	if trimmed == "" {
+		return dst.DecodeText(nil, nil)
+	}
+	return dst.DecodeText(nil, []byte(trimmed))
+}
+
 // Scan implements the database/sql Scanner interface.
 func (dst *Inet) Scan(src interface{}) error {
 	if src == nil {

inet_test.go

@@ -114,3 +114,60 @@ func TestInetAssignTo(t *testing.T) {
 		}
 	}
 }
+
+func TestInetMarshalJSON(t *testing.T) {
+	successfulTests := []struct {
+		json   string
+		source pgtype.Inet
+	}{
+		{source: pgtype.Inet{IPNet: mustParseCIDR(t, "127.0.0.1/32"), Status: pgtype.Present}, json: `"127.0.0.1/32"`},
+		{source: pgtype.Inet{IPNet: mustParseCIDR(t, "2607:f8b0:4009:80b::200e/128"), Status: pgtype.Present}, json: `"2607:f8b0:4009:80b::200e/128"`},
+		{source: pgtype.Inet{Status: pgtype.Null}, json: `""`},
+		{source: pgtype.Inet{}, json: `""`},
+	}
+
+	for i, tt := range successfulTests {
+		got, err := tt.source.MarshalJSON()
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+		if !reflect.DeepEqual(got, []byte(tt.json)) {
+			t.Errorf("%d: expected JSON `%s`, but it was %s", i, tt.json, string(got))
+		}
+	}
+}
+
+func TestInetUnmarshalJSON(t *testing.T) {
+	successfulTests := []struct {
+		json     string
+		expected pgtype.Inet
+	}{
+		{expected: pgtype.Inet{IPNet: mustParseCIDR(t, "127.0.0.1/32"), Status: pgtype.Present}, json: `"127.0.0.1/32"`},
+		{expected: pgtype.Inet{IPNet: mustParseCIDR(t, "127.0.0.1/32"), Status: pgtype.Present}, json: `"127.0.0.1"`},
+		{expected: pgtype.Inet{IPNet: mustParseCIDR(t, "2607:f8b0:4009:80b::200e/128"), Status: pgtype.Present}, json: `"2607:f8b0:4009:80b::200e/128"`},
+		{expected: pgtype.Inet{IPNet: mustParseCIDR(t, "2607:f8b0:4009:80b::200e/128"), Status: pgtype.Present}, json: `"2607:f8b0:4009:80b::200e"`},
+		{expected: pgtype.Inet{Status: pgtype.Null}, json: `""`}, // empty is OK, equivalent to our null struct
+	}
+	badJSON := []string{
+		`"127.0.0.1/"`,         // no network
+		`"444.555.666.777/32"`, // bad addr
+		`"nonsense"`,           // bad everything
+	}
+
+	for i, tt := range successfulTests {
+		got := pgtype.Inet{}
+		if err := got.UnmarshalJSON([]byte(tt.json)); err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+		if !reflect.DeepEqual(got, tt.expected) {
+			t.Errorf("%d: expected %v from JSON `%s`, but it was %v", i, tt.expected, tt.json, got)
+		}
+	}
+
+	for i, example := range badJSON {
+		got := pgtype.Inet{}
+		if err := got.UnmarshalJSON([]byte(example)); err == nil {
+			t.Errorf("%d: Expected error for %s, but got none", i, example)
+		}
+	}
+}