Instead of native map[string]string, use type pgx.Hstore instead

conn.go

@@ -519,8 +519,6 @@ func (c *Conn) sendPreparedQuery(ps *PreparedStatement, arguments ...interface{}
 			err = arg.Encode(wbuf, oid)
 		case string:
 			err = encodeText(wbuf, arguments[i])
-		case map[string]string:
-			err = encodeHstore(wbuf, arguments[i])
 		default:
 			switch oid {
 			case BoolOid:

query.go

@@ -254,8 +254,6 @@ func (rows *Rows) Scan(dest ...interface{}) (err error) {
 			default:
 				rows.Fatal(fmt.Errorf("Can't convert OID %v to time.Time", vr.Type().DataType))
 			}
-		case *map[string]string:
-			*d = decodeHstore(vr)
 		case Scanner:
 			err = d.Scan(vr)
 			if err != nil {

values.go

@@ -421,7 +421,66 @@ func (n NullTime) Encode(w *WriteBuf, oid Oid) error {
 	return encodeTimestampTz(w, n.Time)
 }
 
-// NullHstore represents an hstore that can be null or have null values
+//Hstore represents an hstore column. It does not support a null column or null
+// key values (use NullHstore for this). Hstore implements the Scanner and
+// TextEncoder interfaces so it may be used both as an argument to Query[Row]
+// and a destination for Scan for prepared and unprepared queries.
+type Hstore map[string]string
+
+func (h *Hstore) Scan(vr *ValueReader) error {
+	//oid for hstore not standardized, so we check its type name
+	if vr.Type().DataTypeName != "hstore" {
+		vr.Fatal(ProtocolError(fmt.Sprintf("Cannot decode type %s into Hstore", vr.Type().DataTypeName)))
+		return nil
+	}
+
+	if vr.Len() == -1 {
+		vr.Fatal(ProtocolError("Cannot decode null column into Hstore"))
+		return nil
+	}
+
+	switch vr.Type().FormatCode {
+	case TextFormatCode:
+		m, err := parseHstoreToMap(vr.ReadString(vr.Len()))
+		if err != nil {
+			vr.Fatal(ProtocolError(fmt.Sprintf("Can't decode hstore column: %v", err)))
+			return nil
+		}
+		hm := Hstore(m)
+		*h = hm
+		return nil
+	case BinaryFormatCode:
+		vr.Fatal(ProtocolError("Can't decode binary hstore"))
+		return nil
+	default:
+		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
+		return nil
+	}
+}
+
+func (h Hstore) FormatCode() int16 { return TextFormatCode }
+
+func (h Hstore) Encode(w *WriteBuf, oid Oid) error {
+	var buf bytes.Buffer
+
+	i := 0
+	for k, v := range h {
+		i++
+		ks := strings.Replace(k, `\`, `\\`, -1)
+		ks = strings.Replace(ks, `"`, `\"`, -1)
+		vs := strings.Replace(v, `\`, `\\`, -1)
+		vs = strings.Replace(vs, `"`, `\"`, -1)
+		buf.WriteString(fmt.Sprintf(`"%s"=>"%s"`, ks, vs))
+		if i < len(h) {
+			buf.WriteString(", ")
+		}
+	}
+	w.WriteInt32(int32(buf.Len()))
+	w.WriteBytes(buf.Bytes())
+	return nil
+}
+
+// NullHstore represents an hstore column that can be null or have null values
 // associated with its keys.  NullHstore implements the Scanner and TextEncoder
 // interfaces so it may be used both as an argument to Query[Row] and a
 // destination for Scan for prepared and unprepared queries.
@@ -437,7 +496,7 @@ type NullHstore struct {
 func (h *NullHstore) Scan(vr *ValueReader) error {
 	//oid for hstore not standardized, so we check its type name
 	if vr.Type().DataTypeName != "hstore" {
-		vr.Fatal(ProtocolError(fmt.Sprintf("Cannot decode type %s into map[string]string", vr.Type().DataTypeName)))
+		vr.Fatal(ProtocolError(fmt.Sprintf("Cannot decode type %s into NullHstore", vr.Type().DataTypeName)))
 		return nil
 	}
 
@@ -1122,60 +1181,6 @@ func encodeTimestamp(w *WriteBuf, value interface{}) error {
 	return encodeText(w, s)
 }
 
-func decodeHstore(vr *ValueReader) map[string]string {
-	//oid for hstore not standardized, so we check its type name
-	if vr.Type().DataTypeName != "hstore" {
-		vr.Fatal(ProtocolError(fmt.Sprintf("Cannot decode type %s into map[string]string", vr.Type().DataTypeName)))
-		return nil
-	}
-
-	if vr.Len() == -1 {
-		vr.Fatal(ProtocolError("Cannot decode null into map[string]string"))
-		return nil
-	}
-
-	switch vr.Type().FormatCode {
-	case TextFormatCode:
-		m, err := parseHstoreToMap(vr.ReadString(vr.Len()))
-		if err != nil {
-			vr.Fatal(ProtocolError(fmt.Sprintf("Can't decode hstore column: %v", err)))
-			return nil
-		}
-		return m
-	case BinaryFormatCode:
-		vr.Fatal(ProtocolError("Can't decode binary hstore"))
-		return nil
-	default:
-		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
-		return nil
-	}
-}
-
-func encodeHstore(w *WriteBuf, value interface{}) error {
-	var buf bytes.Buffer
-
-	h, ok := value.(map[string]string)
-	if !ok {
-		return fmt.Errorf("Expected map[string]string, received %T", value)
-	}
-
-	i := 0
-	for k, v := range h {
-		i++
-		ks := strings.Replace(k, `\`, `\\`, -1)
-		ks = strings.Replace(ks, `"`, `\"`, -1)
-		vs := strings.Replace(v, `\`, `\\`, -1)
-		vs = strings.Replace(vs, `"`, `\"`, -1)
-		buf.WriteString(fmt.Sprintf(`"%s"=>"%s"`, ks, vs))
-		if i < len(h) {
-			buf.WriteString(", ")
-		}
-	}
-	w.WriteInt32(int32(buf.Len()))
-	w.WriteBytes(buf.Bytes())
-	return nil
-}
-
 func decode1dArrayHeader(vr *ValueReader) (length int32, err error) {
 	numDims := vr.ReadInt32()
 	if numDims == 0 {