statement: Fix conversion of Valuer (go-sql-driver#710)

Updates go-sql-driver#709 
Fixes go-sql-driver#706

Author: linxGnu

AUTHORS

@@ -46,6 +46,7 @@ Kamil Dziedzic <kamil at klecza.pl>
 Kevin Malachowski <kevin at chowski.com>
 Lennart Rudolph <lrudolph at hmc.edu>
 Leonardo YongUk Kim <dalinaum at gmail.com>
+Linh Tran Tuan <linhduonggnu at gmail.com>
 Lion Yang <lion at aosc.xyz>
 Luca Looz <luca.looz92 at gmail.com>
 Lucas Liu <extrafliu at gmail.com>

connection_go18.go

@@ -197,10 +197,6 @@ func (mc *mysqlConn) startWatcher() {
 }
 
 func (mc *mysqlConn) CheckNamedValue(nv *driver.NamedValue) (err error) {
-	value, err := converter{}.ConvertValue(nv.Value)
-	if err != nil {
-		return driver.ErrSkip
-	}
-	nv.Value = value
+	nv.Value, err = converter{}.ConvertValue(nv.Value)
 	return
 }

driver_test.go

@@ -529,6 +529,55 @@ func TestValuer(t *testing.T) {
 	})
 }
 
+type testValuerWithValidation struct {
+	value string
+}
+
+func (tv testValuerWithValidation) Value() (driver.Value, error) {
+	if len(tv.value) == 0 {
+		return nil, fmt.Errorf("Invalid string valuer. Value must not be empty")
+	}
+
+	return tv.value, nil
+}
+
+func TestValuerWithValidation(t *testing.T) {
+	runTests(t, dsn, func(dbt *DBTest) {
+		in := testValuerWithValidation{"a_value"}
+		var out string
+		var rows *sql.Rows
+
+		dbt.mustExec("CREATE TABLE testValuer (value VARCHAR(255)) CHARACTER SET utf8")
+		dbt.mustExec("INSERT INTO testValuer VALUES (?)", in)
+
+		rows = dbt.mustQuery("SELECT value FROM testValuer")
+		defer rows.Close()
+
+		if rows.Next() {
+			rows.Scan(&out)
+			if in.value != out {
+				dbt.Errorf("Valuer: %v != %s", in, out)
+			}
+		} else {
+			dbt.Errorf("Valuer: no data")
+		}
+
+		if _, err := dbt.db.Exec("INSERT INTO testValuer VALUES (?)", testValuerWithValidation{""}); err == nil {
+			dbt.Errorf("Failed to check valuer error")
+		}
+
+		if _, err := dbt.db.Exec("INSERT INTO testValuer VALUES (?)", nil); err != nil {
+			dbt.Errorf("Failed to check nil")
+		}
+
+		if _, err := dbt.db.Exec("INSERT INTO testValuer VALUES (?)", map[string]bool{}); err == nil {
+			dbt.Errorf("Failed to check not valuer")
+		}
+
+		dbt.mustExec("DROP TABLE IF EXISTS testValuer")
+	})
+}
+
 type timeTests struct {
 	dbtype  string
 	tlayout string

statement.go

@@ -137,6 +137,12 @@ func (c converter) ConvertValue(v interface{}) (driver.Value, error) {
 		return v, nil
 	}
 
+	if v != nil {
+		if valuer, ok := v.(driver.Valuer); ok {
+			return valuer.Value()
+		}
+	}
+
 	rv := reflect.ValueOf(v)
 	switch rv.Kind() {
 	case reflect.Ptr: