ScanRowValue accepts interface{} dst

convert.go

@@ -442,7 +442,7 @@ func GetAssignToDstType(dst interface{}) (interface{}, bool) {
 // most of them implement BinaryDecoder interface.
 //
 // ScanRowValue takes ownership of src, caller MUST not use it after call
-func ScanRowValue(ci *ConnInfo, src []byte, dst ...BinaryDecoder) error {
+func ScanRowValue(ci *ConnInfo, src []byte, dst ...interface{}) error {
 	fieldIter, fieldCount, err := binary.NewRecordFieldIterator(src)
 	if err != nil {
 		return err
@@ -452,17 +452,17 @@ func ScanRowValue(ci *ConnInfo, src []byte, dst ...BinaryDecoder) error {
 		return errors.Errorf("can't scan row value, number of fields don't match: found=%d expected=%d", fieldCount, len(dst))
 	}
 
-	_, fieldBytes, eof, err := fieldIter.Next()
+	fieldOID, fieldBytes, eof, err := fieldIter.Next()
 	for i := 0; !eof; i++ {
 		if err != nil {
 			return err
 		}
 
-		if err = dst[i].DecodeBinary(ci, fieldBytes); err != nil {
+		if err = ci.Scan(fieldOID, BinaryFormatCode, fieldBytes, dst[i]); err != nil {
 			return err
 		}
 
-		_, fieldBytes, eof, err = fieldIter.Next()
+		fieldOID, fieldBytes, eof, err = fieldIter.Next()
 	}
 
 	return nil

custom_composite_test.go

@@ -20,21 +20,7 @@ func (dst *MyType) DecodeBinary(ci *pgtype.ConnInfo, src []byte) error {
 		return errors.New("NULL values can't be decoded. Scan into a &*MyType to handle NULLs")
 	}
 
-	a := pgtype.Int4{}
-	b := pgtype.Text{}
-
-	if err := pgtype.ScanRowValue(ci, src, &a, &b); err != nil {
-		return err
-	}
-
-	// type compatibility is checked by AssignTo
-	// only lossless assignments will succeed
-	if err := a.AssignTo(&dst.a); err != nil {
-		return err
-	}
-
-	// AssignTo also deals with null value handling
-	if err := b.AssignTo(&dst.b); err != nil {
+	if err := pgtype.ScanRowValue(ci, src, &dst.a, &dst.b); err != nil {
 		return err
 	}
 

pgtype.go

@@ -459,8 +459,6 @@ func (ci *ConnInfo) Scan(oid uint32, formatCode int16, buf []byte, dest interfac
 			} else {
 				return errors.Errorf("%T is not a pgtype.TextDecoder", dt.Value)
 			}
-		default:
-			return errors.Errorf("unknown format code: %v", formatCode)
 		}
 
 		if !isFastType {

record_test.go

@@ -93,7 +93,7 @@ func TestScanRowValue(t *testing.T) {
 			t.Fatal(err)
 		}
 		t.Run(tt.sql, func(t *testing.T) {
-			desc := []pgtype.BinaryDecoder{}
+			desc := []interface{}{}
 			for _, f := range tt.expected.Fields {
 				desc = append(desc, f.(pgtype.BinaryDecoder))
 			}