Add JSON/JSONB support

conn.go

@@ -799,6 +799,10 @@ func (c *Conn) sendPreparedQuery(ps *PreparedStatement, arguments ...interface{}
 				err = encodeTimestampArray(wbuf, arguments[i], TimestampTzOid)
 			case OidOid:
 				err = encodeOid(wbuf, arguments[i])
+			case JsonOid:
+				err = encodeJson(wbuf, arguments[i])
+			case JsonbOid:
+				err = encodeJson(wbuf, arguments[i])
 			default:
 				return SerializationError(fmt.Sprintf("Cannot encode %T into oid %v - %T must implement Encoder or be converted to a string", arg, oid, arg))
 			}

query.go

@@ -284,7 +284,14 @@ func (rows *Rows) Scan(dest ...interface{}) (err error) {
 				rows.Fatal(err)
 			}
 		default:
-			rows.Fatal(fmt.Errorf("Scan cannot decode into %T", d))
+			switch vr.Type().DataType {
+			case JsonOid:
+				decodeJson(vr, &d)
+			case JsonbOid:
+				decodeJson(vr, &d)
+			default:
+				rows.Fatal(fmt.Errorf("Scan cannot decode into %T", d))
+			}
 		}
 
 		if vr.Err() != nil {
@@ -360,6 +367,14 @@ func (rows *Rows) Values() ([]interface{}, error) {
 				values = append(values, decodeTimestamp(vr))
 			case InetOid, CidrOid:
 				values = append(values, decodeInet(vr))
+			case JsonOid:
+				var d interface{}
+				decodeJson(vr, &d)
+				values = append(values, d)
+			case JsonbOid:
+				var d interface{}
+				decodeJson(vr, &d)
+				values = append(values, d)
 			default:
 				rows.Fatal(errors.New("Values cannot handle binary format non-intrinsic types"))
 			}

values.go

@@ -2,6 +2,7 @@ package pgx
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"math"
 	"net"
@@ -19,6 +20,7 @@ const (
 	Int4Oid             = 23
 	TextOid             = 25
 	OidOid              = 26
+	JsonOid             = 114
 	CidrOid             = 650
 	Float4Oid           = 700
 	Float8Oid           = 701
@@ -37,6 +39,7 @@ const (
 	TimestampArrayOid   = 1115
 	TimestampTzOid      = 1184
 	TimestampTzArrayOid = 1185
+	JsonbOid            = 3802
 )
 
 // PostgreSQL format codes
@@ -995,6 +998,28 @@ func encodeBytea(w *WriteBuf, value interface{}) error {
 	return nil
 }
 
+func decodeJson(vr *ValueReader, d interface{}) error {
+	if vr.Len() == -1 {
+		return nil
+	}
+
+	if vr.Type().DataType != JsonOid && vr.Type().DataType != JsonbOid {
+		vr.Fatal(ProtocolError(fmt.Sprintf("Cannot decode oid %v into json", vr.Type().DataType)))
+	}
+
+	bytes := vr.ReadBytes(vr.Len())
+	return json.Unmarshal(bytes, d)
+}
+
+func encodeJson(w *WriteBuf, value interface{}) error {
+	s, err := json.Marshal(value)
+	if err != nil {
+		fmt.Errorf("Failed to encode json from type: %T", value)
+	}
+
+	return encodeText(w, s)
+}
+
 func decodeDate(vr *ValueReader) time.Time {
 	var zeroTime time.Time
 

values_test.go

@@ -65,6 +65,46 @@ func TestTimestampTzTranscode(t *testing.T) {
 	}
 }
 
+func TestJsonTranscode(t *testing.T) {
+	t.Parallel()
+
+	conn := mustConnect(t, *defaultConnConfig)
+	defer closeConn(t, conn)
+
+	m := map[string]string{
+		"key": "value",
+	}
+	var outputJson map[string]string
+
+	err := conn.QueryRow("select $1::json", m).Scan(&outputJson)
+	if err != nil {
+		t.Fatalf("QueryRow Scan failed: %v", err)
+	}
+	if m["key"] != outputJson["key"] {
+		t.Errorf("Did not transcode json successfully: %v is not %v", outputJson["key"], m["key"])
+	}
+}
+
+func TestJsonbTranscode(t *testing.T) {
+	t.Parallel()
+
+	conn := mustConnect(t, *defaultConnConfig)
+	defer closeConn(t, conn)
+
+	m := map[string]string{
+		"key": "value",
+	}
+	var outputJson map[string]string
+
+	err := conn.QueryRow("select $1::jsonb", m).Scan(&outputJson)
+	if err != nil {
+		t.Fatalf("QueryRow Scan failed: %v", err)
+	}
+	if m["key"] != outputJson["key"] {
+		t.Errorf("Did not transcode jsonb successfully: %v is not %v", outputJson["key"], m["key"])
+	}
+}
+
 func mustParseCIDR(t *testing.T, s string) net.IPNet {
 	_, ipnet, err := net.ParseCIDR(s)
 	if err != nil {