Problem with database/sql Nullable struct

[linxGnu]

Issue description

Problem with insert/update null field using sql.NullInt64 and others database/sql Nullable struct

Example code

package main

import (
	_ "github.com/go-sql-driver/mysql"

	"database/sql"
	"fmt"
)

func main() {
	dsn := "root:123@tcp(localhost:3306)/tmp?charset=utf8&collation=utf8_general_ci&parseTime=true&loc=Asia%2FHo_Chi_Minh"
	db, _ := sql.Open("mysql", dsn)

	fmt.Println(db.Exec("INSERT INTO test (id, phone, address) VALUES (?, ?, ?)", 10, sql.NullInt64{Valid: true, Int64: 123}, sql.NullString{Valid: true, String: "abc"}))
}

Error log

<nil> sql: converting argument $2 type: unsupported type sql.NullInt64, a struct

Configuration

Driver version (or git SHA): v1.3-46-g78d399c

Go version: go1.9.2 darwin/amd64

Server version: MariaDB 10.2

Server OS: MacOS X 10.13.1

[percona-csalguero]

Is it correct that you have 3 fields in your fields list but only 2 placeholders and values?

[julienschmidt]

sql.NullInt64 is a Scan struct, not for inserting. That means it should be used for retrieving values from the DB, not the other way round.
If you want to insert the value of such struct, then access it via .Value

[linxGnu]

@julienschmidt : sql.NullInt64 also has driver Valuer interface which is for inserting/updating to database. I did revert to previous version of the library (v1.3-45) and things are fine.

@percona-csalguero : thanks for your quick look, I have updated the code above.

[julienschmidt]

Is then maybe #708 the reason?

[linxGnu]

I think the main reason is similar to #708.

But returning driver.ErrSkip as in #708 is not true. The lib should call Valuer interface func when parsing instead of returning error. Only error returning from interface should be caught.