Introduce timeTruncate parameter

This introduces `timeTruncate` parameter that will truncate `time.Time` values in query arguments.

AUTHORS

@@ -86,6 +86,7 @@ Oliver Bone <owbone at github.com>
 Olivier Mengué <dolmen at cpan.org>
 oscarzhao <oscarzhaosl at gmail.com>
 Paul Bonser <misterpib at gmail.com>
+Paulius Lozys <pauliuslozys at gmail.com>
 Peter Schultz <peter.schultz at classmarkets.com>
 Phil Porada <philporada at gmail.com>
 Rebecca Chin <rchin at pivotal.io>

README.md

@@ -285,6 +285,15 @@ Note that this sets the location for time.Time values but does not change MySQL'
 
 Please keep in mind, that param values must be [url.QueryEscape](https://golang.org/pkg/net/url/#QueryEscape)'ed. Alternatively you can manually replace the `/` with `%2F`. For example `US/Pacific` would be `loc=US%2FPacific`.
 
+##### `timeTruncate`
+
+```
+Type:           duration
+Default:        0
+```
+
+Truncate time values to the specified duration. The value must be a decimal number with a unit suffix (*"ms"*, *"s"*, *"m"*, *"h"*), such as *"30s"*, *"0.5m"* or *"1m30s"*.
+
 ##### `maxAllowedPacket`
 ```
 Type:          decimal number

connection.go

@@ -251,7 +251,7 @@ func (mc *mysqlConn) interpolateParams(query string, args []driver.Value) (strin
 				buf = append(buf, "'0000-00-00'"...)
 			} else {
 				buf = append(buf, '\'')
-				buf, err = appendDateTime(buf, v.In(mc.cfg.Loc))
+				buf, err = appendDateTime(buf, v.In(mc.cfg.Loc), mc.cfg.TimeTruncate)
 				if err != nil {
 					return "", err
 				}

dsn.go

@@ -48,6 +48,7 @@ type Config struct {
 	pubKey               *rsa.PublicKey    // Server public key
 	TLSConfig            string            // TLS configuration name
 	TLS                  *tls.Config       // TLS configuration, its priority is higher than TLSConfig
+	TimeTruncate         time.Duration     // Truncate time.Time values to the specified duration
 	Timeout              time.Duration     // Dial timeout
 	ReadTimeout          time.Duration     // I/O read timeout
 	WriteTimeout         time.Duration     // I/O write timeout
@@ -262,6 +263,10 @@ func (cfg *Config) FormatDSN() string {
 		writeDSNParam(&buf, &hasParam, "parseTime", "true")
 	}
 
+	if cfg.TimeTruncate > 0 {
+		writeDSNParam(&buf, &hasParam, "timeTruncate", cfg.TimeTruncate.String())
+	}
+
 	if cfg.ReadTimeout > 0 {
 		writeDSNParam(&buf, &hasParam, "readTimeout", cfg.ReadTimeout.String())
 	}
@@ -502,6 +507,13 @@ func parseDSNParams(cfg *Config, params string) (err error) {
 				return errors.New("invalid bool value: " + value)
 			}
 
+		// time.Time truncation
+		case "timeTruncate":
+			cfg.TimeTruncate, err = time.ParseDuration(value)
+			if err != nil {
+				return
+			}
+
 		// I/O read Timeout
 		case "readTimeout":
 			cfg.ReadTimeout, err = time.ParseDuration(value)

dsn_test.go

@@ -74,6 +74,9 @@ var testDSNs = []struct {
 }, {
 	"tcp(de:ad:be:ef::ca:fe)/dbname",
 	&Config{Net: "tcp", Addr: "[de:ad:be:ef::ca:fe]:3306", DBName: "dbname", Loc: time.UTC, MaxAllowedPacket: defaultMaxAllowedPacket, Logger: defaultLogger, AllowNativePasswords: true, CheckConnLiveness: true},
+}, {
+	"user:password@/dbname?loc=UTC&timeout=30s&parseTime=true&timeTruncate=1h",
+	&Config{User: "user", Passwd: "password", Net: "tcp", Addr: "127.0.0.1:3306", DBName: "dbname", Loc: time.UTC, Timeout: 30 * time.Second, ParseTime: true, TimeTruncate: time.Hour},
 },
 }
 

packets.go

@@ -1172,7 +1172,7 @@ func (stmt *mysqlStmt) writeExecutePacket(args []driver.Value) error {
 				if v.IsZero() {
 					b = append(b, "0000-00-00"...)
 				} else {
-					b, err = appendDateTime(b, v.In(mc.cfg.Loc))
+					b, err = appendDateTime(b, v.In(mc.cfg.Loc), mc.cfg.TimeTruncate)
 					if err != nil {
 						return err
 					}

utils.go

@@ -265,7 +265,11 @@ func parseBinaryDateTime(num uint64, data []byte, loc *time.Location) (driver.Va
 	return nil, fmt.Errorf("invalid DATETIME packet length %d", num)
 }
 
-func appendDateTime(buf []byte, t time.Time) ([]byte, error) {
+func appendDateTime(buf []byte, t time.Time, timeTruncate time.Duration) ([]byte, error) {
+	if timeTruncate > 0 {
+		t = t.Truncate(timeTruncate)
+	}
+
 	year, month, day := t.Date()
 	hour, min, sec := t.Clock()
 	nsec := t.Nanosecond()

utils_test.go

@@ -237,8 +237,9 @@ func TestIsolationLevelMapping(t *testing.T) {
 
 func TestAppendDateTime(t *testing.T) {
 	tests := []struct {
-		t   time.Time
-		str string
+		t            time.Time
+		str          string
+		timeTruncate time.Duration
 	}{
 		{
 			t:   time.Date(1234, 5, 6, 0, 0, 0, 0, time.UTC),
@@ -276,10 +277,56 @@ func TestAppendDateTime(t *testing.T) {
 			t:   time.Date(1, 1, 1, 0, 0, 0, 0, time.UTC),
 			str: "0001-01-01",
 		},
+		// Truncated time
+		{
+			t:            time.Date(1234, 5, 6, 0, 0, 0, 0, time.UTC),
+			str:          "1234-05-06",
+			timeTruncate: time.Second,
+		},
+		{
+			t:            time.Date(4567, 12, 31, 12, 0, 0, 0, time.UTC),
+			str:          "4567-12-31 12:00:00",
+			timeTruncate: time.Minute,
+		},
+		{
+			t:            time.Date(2020, 5, 30, 12, 34, 0, 0, time.UTC),
+			str:          "2020-05-30 12:34:00",
+			timeTruncate: 0,
+		},
+		{
+			t:            time.Date(2020, 5, 30, 12, 34, 56, 0, time.UTC),
+			str:          "2020-05-30 12:34:56",
+			timeTruncate: time.Second,
+		},
+		{
+			t:            time.Date(2020, 5, 30, 22, 33, 44, 123000000, time.UTC),
+			str:          "2020-05-30 22:33:44",
+			timeTruncate: time.Second,
+		},
+		{
+			t:            time.Date(2020, 5, 30, 22, 33, 44, 123456000, time.UTC),
+			str:          "2020-05-30 22:33:44.123",
+			timeTruncate: time.Millisecond,
+		},
+		{
+			t:            time.Date(2020, 5, 30, 22, 33, 44, 123456789, time.UTC),
+			str:          "2020-05-30 22:33:44",
+			timeTruncate: time.Second,
+		},
+		{
+			t:            time.Date(9999, 12, 31, 23, 59, 59, 999999999, time.UTC),
+			str:          "9999-12-31 23:59:59.999999999",
+			timeTruncate: 0,
+		},
+		{
+			t:            time.Date(1, 1, 1, 1, 1, 1, 1, time.UTC),
+			str:          "0001-01-01",
+			timeTruncate: 365 * 24 * time.Hour,
+		},
 	}
 	for _, v := range tests {
 		buf := make([]byte, 0, 32)
-		buf, _ = appendDateTime(buf, v.t)
+		buf, _ = appendDateTime(buf, v.t, v.timeTruncate)
 		if str := string(buf); str != v.str {
 			t.Errorf("appendDateTime(%v), have: %s, want: %s", v.t, str, v.str)
 		}
@@ -289,7 +336,7 @@ func TestAppendDateTime(t *testing.T) {
 	{
 		v := time.Date(0, 1, 1, 0, 0, 0, 0, time.UTC)
 		buf := make([]byte, 0, 32)
-		_, err := appendDateTime(buf, v)
+		_, err := appendDateTime(buf, v, 0)
 		if err == nil {
 			t.Error("want an error")
 			return
@@ -298,7 +345,7 @@ func TestAppendDateTime(t *testing.T) {
 	{
 		v := time.Date(10000, 1, 1, 0, 0, 0, 0, time.UTC)
 		buf := make([]byte, 0, 32)
-		_, err := appendDateTime(buf, v)
+		_, err := appendDateTime(buf, v, 0)
 		if err == nil {
 			t.Error("want an error")
 			return