add String() for FieldValue (#825)

* add String() for FieldValue

Signed-off-by: lance6716 <[email protected]>

* fix lint

Signed-off-by: lance6716 <[email protected]>

* escape

Signed-off-by: lance6716 <[email protected]>

---------

Signed-off-by: lance6716 <[email protected]>

Author: lance6716

client/client_test.go

@@ -423,3 +423,71 @@ func (s *clientTestSuite) TestStmt_Trans() {
 	str, _ = r.GetString(0, 0)
 	require.Equal(s.T(), `abc`, str)
 }
+
+func (s *clientTestSuite) TestFieldValueString() {
+	_, err := s.c.Execute(
+		`
+CREATE TABLE field_value_test (
+    c_int int,
+    c_bit bit(8),
+    c_tinyint_u tinyint unsigned,
+    c_decimal decimal(10, 5),
+    c_float float(10),
+    c_date date,
+    c_datetime datetime(3),
+    c_timestamp timestamp(4),
+    c_time time(5),
+    c_year year,
+    c_char char(10),
+    c_varchar varchar(10),
+    c_binary binary(10),
+    c_varbinary varbinary(10),
+    c_blob blob,
+    c_enum enum('a', 'b', 'c'),
+    c_set set('a', 'b', 'c'),
+    c_json json,
+    c_null int
+)`)
+	require.NoError(s.T(), err)
+	s.T().Cleanup(func() {
+		_, _ = s.c.Execute(
+			`DROP TABLE field_value_test`)
+	})
+
+	_, err = s.c.Execute(`
+INSERT INTO field_value_test VALUES (
+    1, 2, 3, 4.5, 6.7, 
+    '2019-01-01', '2019-01-01 01:01:01.123', '2019-01-01 01:01:01.1234', '01:01:01.12345', 2019,
+    'cha\'r', 'varchar', 'binary', 'varbinary', 'blob', 'a', 'a,b', '{"a": 1}',
+    NULL
+)`)
+	require.NoError(s.T(), err)
+
+	result, err := s.c.Execute(`SELECT * FROM field_value_test`)
+	require.NoError(s.T(), err)
+	require.Len(s.T(), result.Values, 1)
+	expected := []string{
+		`1`, "'\x02'", `3`, `'4.50000'`, `6.7`,
+		`'2019-01-01'`, `'2019-01-01 01:01:01.123'`, `'2019-01-01 01:01:01.1234'`, `'01:01:01.12345'`, `2019`,
+		`'cha\'r'`, `'varchar'`, "'binary\x00\x00\x00\x00'", `'varbinary'`, `'blob'`, `'a'`, `'a,b'`, `'{"a": 1}'`,
+		`NULL`,
+	}
+	for i, v := range result.Values[0] {
+		require.Equal(s.T(), expected[i], v.String())
+	}
+
+	// test can directly use to build a SQL, though it's not safe in most cases
+	sql := fmt.Sprintf("INSERT INTO field_value_test VALUES (%s)", strings.Join(expected, ","))
+	_, err = s.c.Execute(sql)
+	require.NoError(s.T(), err)
+	result, err = s.c.Execute(`SELECT * FROM field_value_test`)
+	require.NoError(s.T(), err)
+	// check again, everything is same
+	require.Len(s.T(), result.Values, 2)
+	for i, v := range result.Values[0] {
+		require.Equal(s.T(), expected[i], v.String())
+	}
+	for i, v := range result.Values[1] {
+		require.Equal(s.T(), expected[i], v.String())
+	}
+}

mysql/field.go

@@ -2,6 +2,9 @@ package mysql
 
 import (
 	"encoding/binary"
+	"fmt"
+	"strconv"
+	"strings"
 
 	"github.com/go-mysql-org/go-mysql/utils"
 )
@@ -210,3 +213,31 @@ func (fv *FieldValue) Value() interface{} {
 		return nil
 	}
 }
+
+// String returns a MySQL literal string that equals the value.
+func (fv *FieldValue) String() string {
+	switch fv.Type {
+	case FieldValueTypeNull:
+		return "NULL"
+	case FieldValueTypeUnsigned:
+		return strconv.FormatUint(fv.AsUint64(), 10)
+	case FieldValueTypeSigned:
+		return strconv.FormatInt(fv.AsInt64(), 10)
+	case FieldValueTypeFloat:
+		return strconv.FormatFloat(fv.AsFloat64(), 'f', -1, 64)
+	case FieldValueTypeString:
+		b := strings.Builder{}
+		b.Grow(len(fv.str) + 2)
+		b.WriteByte('\'')
+		for i := range fv.str {
+			if fv.str[i] == '\'' {
+				b.WriteByte('\\')
+			}
+			b.WriteByte(fv.str[i])
+		}
+		b.WriteByte('\'')
+		return b.String()
+	default:
+		return fmt.Sprintf("unknown type %d of FieldValue", fv.Type)
+	}
+}