Error detection for mismatched types

conn.go

@@ -760,7 +760,7 @@ func (c *Conn) sendPreparedQuery(ps *PreparedStatement, arguments ...interface{}
 
 		switch arg := arguments[i].(type) {
 		case BinaryEncoder:
-			err = arg.EncodeBinary(wbuf)
+			err = arg.EncodeBinary(wbuf, &ps.FieldDescriptions[i])
 		case TextEncoder:
 			var s string
 			var status byte

values.go

@@ -63,8 +63,14 @@ type TextEncoder interface {
 // BinaryEncoder is an interface used to encode values in binary format for
 // transmission to the PostgreSQL server. It is used by prepared queries.
 type BinaryEncoder interface {
-	// EncodeBinary writes the binary value to w
-	EncodeBinary(w *WriteBuf) error
+	// EncodeBinary writes the binary value to w.
+	//
+	// EncodeBinary MUST check fd.DataType to see if the parameter data type is
+	// compatible. If this is not done, the PostgreSQL server may detect the
+	// error if the expected data size or format of the encoded data does not
+	// match. But if the encoded data is a valid representation of the data type
+	// PostgreSQL expects such as date and int4, incorrect data may be stored.
+	EncodeBinary(w *WriteBuf, fd *FieldDescription) error
 }
 
 // NullFloat32 represents an float4 that may be null.
@@ -96,7 +102,11 @@ func (n NullFloat32) EncodeText() (string, byte, error) {
 	}
 }
 
-func (n NullFloat32) EncodeBinary(w *WriteBuf) error {
+func (n NullFloat32) EncodeBinary(w *WriteBuf, fd *FieldDescription) error {
+	if fd.DataType != Float4Oid {
+		return SerializationError(fmt.Sprintf("NullFloat32.EncodeBinary cannot encode into OID %d", fd.DataType))
+	}
+
 	if !n.Valid {
 		w.WriteInt32(-1)
 		return nil
@@ -134,7 +144,11 @@ func (n NullFloat64) EncodeText() (string, byte, error) {
 	}
 }
 
-func (n NullFloat64) EncodeBinary(w *WriteBuf) error {
+func (n NullFloat64) EncodeBinary(w *WriteBuf, fd *FieldDescription) error {
+	if fd.DataType != Float8Oid {
+		return SerializationError(fmt.Sprintf("NullFloat64.EncodeBinary cannot encode into OID %d", fd.DataType))
+	}
+
 	if !n.Valid {
 		w.WriteInt32(-1)
 		return nil
@@ -201,7 +215,11 @@ func (n NullInt16) EncodeText() (string, byte, error) {
 	}
 }
 
-func (n NullInt16) EncodeBinary(w *WriteBuf) error {
+func (n NullInt16) EncodeBinary(w *WriteBuf, fd *FieldDescription) error {
+	if fd.DataType != Int2Oid {
+		return SerializationError(fmt.Sprintf("NullInt16.EncodeBinary cannot encode into OID %d", fd.DataType))
+	}
+
 	if !n.Valid {
 		w.WriteInt32(-1)
 		return nil
@@ -239,7 +257,11 @@ func (n NullInt32) EncodeText() (string, byte, error) {
 	}
 }
 
-func (n NullInt32) EncodeBinary(w *WriteBuf) error {
+func (n NullInt32) EncodeBinary(w *WriteBuf, fd *FieldDescription) error {
+	if fd.DataType != Int4Oid {
+		return SerializationError(fmt.Sprintf("NullInt32.EncodeBinary cannot encode into OID %d", fd.DataType))
+	}
+
 	if !n.Valid {
 		w.WriteInt32(-1)
 		return nil
@@ -277,7 +299,11 @@ func (n NullInt64) EncodeText() (string, byte, error) {
 	}
 }
 
-func (n NullInt64) EncodeBinary(w *WriteBuf) error {
+func (n NullInt64) EncodeBinary(w *WriteBuf, fd *FieldDescription) error {
+	if fd.DataType != Int8Oid {
+		return SerializationError(fmt.Sprintf("NullInt64.EncodeBinary cannot encode into OID %d", fd.DataType))
+	}
+
 	if !n.Valid {
 		w.WriteInt32(-1)
 		return nil
@@ -315,7 +341,11 @@ func (n NullBool) EncodeText() (string, byte, error) {
 	}
 }
 
-func (n NullBool) EncodeBinary(w *WriteBuf) error {
+func (n NullBool) EncodeBinary(w *WriteBuf, fd *FieldDescription) error {
+	if fd.DataType != BoolOid {
+		return SerializationError(fmt.Sprintf("NullBool.EncodeBinary cannot encode into OID %d", fd.DataType))
+	}
+
 	if !n.Valid {
 		w.WriteInt32(-1)
 		return nil
@@ -354,7 +384,11 @@ func (n NullTime) EncodeText() (string, byte, error) {
 	}
 }
 
-func (n NullTime) EncodeBinary(w *WriteBuf) error {
+func (n NullTime) EncodeBinary(w *WriteBuf, fd *FieldDescription) error {
+	if fd.DataType != TimestampTzOid {
+		return SerializationError(fmt.Sprintf("NullTime.EncodeBinary cannot encode into OID %d", fd.DataType))
+	}
+
 	if !n.Valid {
 		w.WriteInt32(-1)
 		return nil

values_test.go

@@ -250,3 +250,53 @@ func TestNullX(t *testing.T) {
 		}
 	}
 }
+
+func TestNullXMismatch(t *testing.T) {
+	t.Parallel()
+
+	conn := mustConnect(t, *defaultConnConfig)
+	defer closeConn(t, conn)
+
+	type allTypes struct {
+		s   pgx.NullString
+		i16 pgx.NullInt16
+		i32 pgx.NullInt32
+		i64 pgx.NullInt64
+		f32 pgx.NullFloat32
+		f64 pgx.NullFloat64
+		b   pgx.NullBool
+		t   pgx.NullTime
+	}
+
+	var actual, zero allTypes
+
+	tests := []struct {
+		sql       string
+		queryArgs []interface{}
+		scanArgs  []interface{}
+		err       string
+	}{
+		{"select $1::date", []interface{}{pgx.NullString{String: "foo", Valid: true}}, []interface{}{&actual.s}, "invalid input syntax for type date"},
+		{"select $1::date", []interface{}{pgx.NullInt16{Int16: 1, Valid: true}}, []interface{}{&actual.i16}, "cannot encode into OID 1082"},
+		{"select $1::date", []interface{}{pgx.NullInt32{Int32: 1, Valid: true}}, []interface{}{&actual.i32}, "cannot encode into OID 1082"},
+		{"select $1::date", []interface{}{pgx.NullInt64{Int64: 1, Valid: true}}, []interface{}{&actual.i64}, "cannot encode into OID 1082"},
+		{"select $1::date", []interface{}{pgx.NullFloat32{Float32: 1.23, Valid: true}}, []interface{}{&actual.f32}, "cannot encode into OID 1082"},
+		{"select $1::date", []interface{}{pgx.NullFloat64{Float64: 1.23, Valid: true}}, []interface{}{&actual.f64}, "cannot encode into OID 1082"},
+		{"select $1::date", []interface{}{pgx.NullBool{Bool: true, Valid: true}}, []interface{}{&actual.b}, "cannot encode into OID 1082"},
+		{"select $1::date", []interface{}{pgx.NullTime{Time: time.Unix(123, 5000), Valid: true}}, []interface{}{&actual.t}, "cannot encode into OID 1082"},
+	}
+
+	for i, tt := range tests {
+		psName := fmt.Sprintf("ps%d", i)
+		mustPrepare(t, conn, psName, tt.sql)
+
+		actual = zero
+
+		err := conn.QueryRow(psName, tt.queryArgs...).Scan(tt.scanArgs...)
+		if err == nil || !strings.Contains(err.Error(), tt.err) {
+			t.Errorf(`%d. Expected error to contain "%s", but it didn't: %v`, i, tt.err, err)
+		}
+
+		ensureConnValid(t, conn)
+	}
+}