Move "char" to pgtype

conn.go

@@ -270,6 +270,7 @@ func (c *Conn) connect(config ConnConfig, network, address string, tlsConfig *tl
 	c.oidPgtypeValues = map[OID]pgtype.Value{
 		BoolArrayOID:        &pgtype.BoolArray{},
 		BoolOID:             &pgtype.Bool{},
+		CharOID:             &pgtype.QChar{},
 		CIDOID:              &pgtype.CID{},
 		CidrArrayOID:        &pgtype.CidrArray{},
 		CidrOID:             &pgtype.Inet{},

pgtype/pgtype_test.go

@@ -74,12 +74,15 @@ func (f forceBinaryEncoder) EncodeBinary(w io.Writer) error {
 func forceEncoder(e interface{}, formatCode int16) interface{} {
 	switch formatCode {
 	case pgx.TextFormatCode:
-		return forceTextEncoder{e: e.(pgtype.TextEncoder)}
+		if e, ok := e.(pgtype.TextEncoder); ok {
+			return forceTextEncoder{e: e}
+		}
 	case pgx.BinaryFormatCode:
-		return forceBinaryEncoder{e: e.(pgtype.BinaryEncoder)}
+		if e, ok := e.(pgtype.BinaryEncoder); ok {
-	default:
+			return forceBinaryEncoder{e: e.(pgtype.BinaryEncoder)}
-		panic("bad encoder")
+		}
 	}
+	return nil
 }
 
 func testSuccessfulTranscode(t testing.TB, pgTypeName string, values []interface{}) {
@@ -105,9 +108,14 @@ func testSuccessfulTranscodeEqFunc(t testing.TB, pgTypeName string, values []int
 		{name: "BinaryFormat", formatCode: pgx.BinaryFormatCode},
 	}
 
-	for _, fc := range formats {
+	for i, v := range values {
-		ps.FieldDescriptions[0].FormatCode = fc.formatCode
+		for _, fc := range formats {
-		for i, v := range values {
+			ps.FieldDescriptions[0].FormatCode = fc.formatCode
+			vEncoder := forceEncoder(v, fc.formatCode)
+			if vEncoder == nil {
+				t.Logf("%v does not implement %v", fc.name)
+				continue
+			}
 			// Derefence value if it is a pointer
 			derefV := v
 			refVal := reflect.ValueOf(v)

pgtype/qchar.go

@@ -0,0 +1,144 @@
+package pgtype
+
+import (
+	"fmt"
+	"io"
+	"math"
+	"strconv"
+
+	"github.com/jackc/pgx/pgio"
+)
+
+// QChar is for PostgreSQL's special 8-bit-only "char" type more akin to the C
+// language's char type, or Go's byte type. (Note that the name in PostgreSQL
+// itself is "char", in double-quotes, and not char.) It gets used a lot in
+// PostgreSQL's system tables to hold a single ASCII character value (eg
+// pg_class.relkind). It is named Qchar for quoted char to disambiguate from SQL
+// standard type char.
+//
+// Not all possible values of QChar are representable in the text format.
+// Therefore, QChar does not implement TextEncoder and TextDecoder.
+type QChar struct {
+	Int    int8
+	Status Status
+}
+
+func (dst *QChar) ConvertFrom(src interface{}) error {
+	switch value := src.(type) {
+	case QChar:
+		*dst = value
+	case int8:
+		*dst = QChar{Int: value, Status: Present}
+	case uint8:
+		if value > math.MaxInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		*dst = QChar{Int: int8(value), Status: Present}
+	case int16:
+		if value < math.MinInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		if value > math.MaxInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		*dst = QChar{Int: int8(value), Status: Present}
+	case uint16:
+		if value > math.MaxInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		*dst = QChar{Int: int8(value), Status: Present}
+	case int32:
+		if value < math.MinInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		if value > math.MaxInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		*dst = QChar{Int: int8(value), Status: Present}
+	case uint32:
+		if value > math.MaxInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		*dst = QChar{Int: int8(value), Status: Present}
+	case int64:
+		if value < math.MinInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		if value > math.MaxInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		*dst = QChar{Int: int8(value), Status: Present}
+	case uint64:
+		if value > math.MaxInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		*dst = QChar{Int: int8(value), Status: Present}
+	case int:
+		if value < math.MinInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		if value > math.MaxInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		*dst = QChar{Int: int8(value), Status: Present}
+	case uint:
+		if value > math.MaxInt8 {
+			return fmt.Errorf("%d is greater than maximum value for QChar", value)
+		}
+		*dst = QChar{Int: int8(value), Status: Present}
+	case string:
+		num, err := strconv.ParseInt(value, 10, 8)
+		if err != nil {
+			return err
+		}
+		*dst = QChar{Int: int8(num), Status: Present}
+	default:
+		if originalSrc, ok := underlyingNumberType(src); ok {
+			return dst.ConvertFrom(originalSrc)
+		}
+		return fmt.Errorf("cannot convert %v to QChar", value)
+	}
+
+	return nil
+}
+
+func (src *QChar) AssignTo(dst interface{}) error {
+	return int64AssignTo(int64(src.Int), src.Status, dst)
+}
+
+func (dst *QChar) DecodeBinary(r io.Reader) error {
+	size, err := pgio.ReadInt32(r)
+	if err != nil {
+		return err
+	}
+
+	if size == -1 {
+		*dst = QChar{Status: Null}
+		return nil
+	}
+
+	if size != 1 {
+		return fmt.Errorf(`invalid length for "char": %v`, size)
+	}
+
+	byt, err := pgio.ReadByte(r)
+	if err != nil {
+		return err
+	}
+
+	*dst = QChar{Int: int8(byt), Status: Present}
+	return nil
+}
+
+func (src QChar) EncodeBinary(w io.Writer) error {
+	if done, err := encodeNotPresent(w, src.Status); done {
+		return err
+	}
+
+	_, err := pgio.WriteInt32(w, 1)
+	if err != nil {
+		return nil
+	}
+
+	return pgio.WriteByte(w, byte(src.Int))
+}

pgtype/qchar_test.go

@@ -0,0 +1,140 @@
+package pgtype_test
+
+import (
+	"math"
+	"reflect"
+	"testing"
+
+	"github.com/jackc/pgx/pgtype"
+)
+
+func TestQCharTranscode(t *testing.T) {
+	testSuccessfulTranscode(t, `"char"`, []interface{}{
+		pgtype.QChar{Int: math.MinInt8, Status: pgtype.Present},
+		pgtype.QChar{Int: -1, Status: pgtype.Present},
+		pgtype.QChar{Int: 0, Status: pgtype.Present},
+		pgtype.QChar{Int: 1, Status: pgtype.Present},
+		pgtype.QChar{Int: math.MaxInt8, Status: pgtype.Present},
+		pgtype.QChar{Int: 0, Status: pgtype.Null},
+	})
+}
+
+func TestQCharConvertFrom(t *testing.T) {
+	successfulTests := []struct {
+		source interface{}
+		result pgtype.QChar
+	}{
+		{source: int8(1), result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+		{source: int16(1), result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+		{source: int32(1), result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+		{source: int64(1), result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+		{source: int8(-1), result: pgtype.QChar{Int: -1, Status: pgtype.Present}},
+		{source: int16(-1), result: pgtype.QChar{Int: -1, Status: pgtype.Present}},
+		{source: int32(-1), result: pgtype.QChar{Int: -1, Status: pgtype.Present}},
+		{source: int64(-1), result: pgtype.QChar{Int: -1, Status: pgtype.Present}},
+		{source: uint8(1), result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+		{source: uint16(1), result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+		{source: uint32(1), result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+		{source: uint64(1), result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+		{source: "1", result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+		{source: _int8(1), result: pgtype.QChar{Int: 1, Status: pgtype.Present}},
+	}
+
+	for i, tt := range successfulTests {
+		var r pgtype.QChar
+		err := r.ConvertFrom(tt.source)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+
+		if r != tt.result {
+			t.Errorf("%d: expected %v to convert to %v, but it was %v", i, tt.source, tt.result, r)
+		}
+	}
+}
+
+func TestQCharAssignTo(t *testing.T) {
+	var i8 int8
+	var i16 int16
+	var i32 int32
+	var i64 int64
+	var i int
+	var ui8 uint8
+	var ui16 uint16
+	var ui32 uint32
+	var ui64 uint64
+	var ui uint
+	var pi8 *int8
+	var _i8 _int8
+	var _pi8 *_int8
+
+	simpleTests := []struct {
+		src      pgtype.QChar
+		dst      interface{}
+		expected interface{}
+	}{
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &i8, expected: int8(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &i16, expected: int16(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &i32, expected: int32(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &i64, expected: int64(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &i, expected: int(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &ui8, expected: uint8(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &ui16, expected: uint16(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &ui32, expected: uint32(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &ui64, expected: uint64(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &ui, expected: uint(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &_i8, expected: _int8(42)},
+		{src: pgtype.QChar{Int: 0, Status: pgtype.Null}, dst: &pi8, expected: ((*int8)(nil))},
+		{src: pgtype.QChar{Int: 0, Status: pgtype.Null}, dst: &_pi8, expected: ((*_int8)(nil))},
+	}
+
+	for i, tt := range simpleTests {
+		err := tt.src.AssignTo(tt.dst)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+
+		if dst := reflect.ValueOf(tt.dst).Elem().Interface(); dst != tt.expected {
+			t.Errorf("%d: expected %v to assign %v, but result was %v", i, tt.src, tt.expected, dst)
+		}
+	}
+
+	pointerAllocTests := []struct {
+		src      pgtype.QChar
+		dst      interface{}
+		expected interface{}
+	}{
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &pi8, expected: int8(42)},
+		{src: pgtype.QChar{Int: 42, Status: pgtype.Present}, dst: &_pi8, expected: _int8(42)},
+	}
+
+	for i, tt := range pointerAllocTests {
+		err := tt.src.AssignTo(tt.dst)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+
+		if dst := reflect.ValueOf(tt.dst).Elem().Elem().Interface(); dst != tt.expected {
+			t.Errorf("%d: expected %v to assign %v, but result was %v", i, tt.src, tt.expected, dst)
+		}
+	}
+
+	errorTests := []struct {
+		src pgtype.QChar
+		dst interface{}
+	}{
+		{src: pgtype.QChar{Int: -1, Status: pgtype.Present}, dst: &ui8},
+		{src: pgtype.QChar{Int: -1, Status: pgtype.Present}, dst: &ui16},
+		{src: pgtype.QChar{Int: -1, Status: pgtype.Present}, dst: &ui32},
+		{src: pgtype.QChar{Int: -1, Status: pgtype.Present}, dst: &ui64},
+		{src: pgtype.QChar{Int: -1, Status: pgtype.Present}, dst: &ui},
+		{src: pgtype.QChar{Int: 0, Status: pgtype.Null}, dst: &i16},
+	}
+
+	for i, tt := range errorTests {
+		err := tt.src.AssignTo(tt.dst)
+		if err == nil {
+			t.Errorf("%d: expected error but none was returned (%v -> %v)", i, tt.src, tt.dst)
+		}
+	}
+}

values.go

@@ -371,52 +371,6 @@ func (n NullAclItem) Encode(w *WriteBuf, oid OID) error {
 	return encodeString(w, oid, string(n.AclItem))
 }
 
-// The pgx.Char type is for PostgreSQL's special 8-bit-only
-// "char" type more akin to the C language's char type, or Go's byte type.
-// (Note that the name in PostgreSQL itself is "char", in double-quotes,
-// and not char.) It gets used a lot in PostgreSQL's system tables to hold
-// a single ASCII character value (eg pg_class.relkind).
-type Char byte
-
-// NullChar represents a pgx.Char that may be null. NullChar implements the
-// Scanner and Encoder interfaces so it may be used both as an argument to
-// Query[Row] and a destination for Scan for prepared and unprepared queries.
-//
-// If Valid is false then the value is NULL.
-type NullChar struct {
-	Char  Char
-	Valid bool // Valid is true if Char is not NULL
-}
-
-func (n *NullChar) Scan(vr *ValueReader) error {
-	if vr.Type().DataType != CharOID {
-		return SerializationError(fmt.Sprintf("NullChar.Scan cannot decode OID %d", vr.Type().DataType))
-	}
-
-	if vr.Len() == -1 {
-		n.Char, n.Valid = 0, false
-		return nil
-	}
-	n.Valid = true
-	n.Char = decodeChar(vr)
-	return vr.Err()
-}
-
-func (n NullChar) FormatCode() int16 { return BinaryFormatCode }
-
-func (n NullChar) Encode(w *WriteBuf, oid OID) error {
-	if oid != CharOID {
-		return SerializationError(fmt.Sprintf("NullChar.Encode cannot encode into OID %d", oid))
-	}
-
-	if !n.Valid {
-		w.WriteInt32(-1)
-		return nil
-	}
-
-	return encodeChar(w, oid, n.Char)
-}
-
 // NullInt16 represents a smallint that may be null. NullInt16 implements the
 // Scanner and Encoder interfaces so it may be used both as an argument to
 // Query[Row] and a destination for Scan for prepared and unprepared queries.
@@ -945,8 +899,6 @@ func Encode(wbuf *WriteBuf, oid OID, arg interface{}) error {
 	}
 
 	switch arg := arg.(type) {
-	case Char:
-		return encodeChar(wbuf, oid, arg)
 	case AclItem:
 		// The aclitem data type goes over the wire using the same format as string,
 		// so just cast to string and use encodeString
@@ -1018,8 +970,6 @@ func decodeByOID(vr *ValueReader) (interface{}, error) {
 // decoding to the built-in functionality.
 func Decode(vr *ValueReader, d interface{}) error {
 	switch v := d.(type) {
-	case *Char:
-		*v = decodeChar(vr)
 	case *AclItem:
 		// aclitem goes over the wire just like text
 		*v = AclItem(decodeText(vr))
@@ -1158,30 +1108,6 @@ func decodeInt8(vr *ValueReader) int64 {
 	return n.Int
 }
 
-func decodeChar(vr *ValueReader) Char {
-	if vr.Len() == -1 {
-		vr.Fatal(ProtocolError("Cannot decode null into char"))
-		return Char(0)
-	}
-
-	if vr.Type().DataType != CharOID {
-		vr.Fatal(ProtocolError(fmt.Sprintf("Cannot decode oid %v into char", vr.Type().DataType)))
-		return Char(0)
-	}
-
-	if vr.Type().FormatCode != BinaryFormatCode {
-		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
-		return Char(0)
-	}
-
-	if vr.Len() != 1 {
-		vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for a char: %d", vr.Len())))
-		return Char(0)
-	}
-
-	return Char(vr.ReadByte())
-}
-
 func decodeInt2(vr *ValueReader) int16 {
 
 	if vr.Type().DataType != Int2OID {
@@ -1216,12 +1142,6 @@ func decodeInt2(vr *ValueReader) int16 {
 	return n.Int
 }
 
-func encodeChar(w *WriteBuf, oid OID, value Char) error {
-	w.WriteInt32(1)
-	w.WriteByte(byte(value))
-	return nil
-}
-
 func decodeInt4(vr *ValueReader) int32 {
 	if vr.Len() == -1 {
 		vr.Fatal(ProtocolError("Cannot decode null into int32"))

values_test.go

@@ -568,7 +568,6 @@ func TestNullX(t *testing.T) {
 		s   pgx.NullString
 		i16 pgx.NullInt16
 		i32 pgx.NullInt32
-		c   pgx.NullChar
 		a   pgx.NullAclItem
 		tid pgx.NullTid
 		i64 pgx.NullInt64
@@ -592,9 +591,6 @@ func TestNullX(t *testing.T) {
 		{"select $1::int2", []interface{}{pgx.NullInt16{Int16: 1, Valid: false}}, []interface{}{&actual.i16}, allTypes{i16: pgx.NullInt16{Int16: 0, Valid: false}}},
 		{"select $1::int4", []interface{}{pgx.NullInt32{Int32: 1, Valid: true}}, []interface{}{&actual.i32}, allTypes{i32: pgx.NullInt32{Int32: 1, Valid: true}}},
 		{"select $1::int4", []interface{}{pgx.NullInt32{Int32: 1, Valid: false}}, []interface{}{&actual.i32}, allTypes{i32: pgx.NullInt32{Int32: 0, Valid: false}}},
-		{"select $1::\"char\"", []interface{}{pgx.NullChar{Char: 1, Valid: true}}, []interface{}{&actual.c}, allTypes{c: pgx.NullChar{Char: 1, Valid: true}}},
-		{"select $1::\"char\"", []interface{}{pgx.NullChar{Char: 1, Valid: false}}, []interface{}{&actual.c}, allTypes{c: pgx.NullChar{Char: 0, Valid: false}}},
-		{"select $1::\"char\"", []interface{}{pgx.NullChar{Char: 255, Valid: true}}, []interface{}{&actual.c}, allTypes{c: pgx.NullChar{Char: 255, Valid: true}}},
 		{"select $1::aclitem", []interface{}{pgx.NullAclItem{AclItem: "postgres=arwdDxt/postgres", Valid: true}}, []interface{}{&actual.a}, allTypes{a: pgx.NullAclItem{AclItem: "postgres=arwdDxt/postgres", Valid: true}}},
 		{"select $1::aclitem", []interface{}{pgx.NullAclItem{AclItem: "postgres=arwdDxt/postgres", Valid: false}}, []interface{}{&actual.a}, allTypes{a: pgx.NullAclItem{AclItem: "", Valid: false}}},
 		// A tricky (and valid) aclitem can still be used, especially with Go's useful backticks