Golang Join array interface

I try to create bulk insert. I use gorm github.com/jinzhu/gorm

import (
    "fmt"
    dB "github.com/edwinlab/api/repositories"
)

func Update() error {
    tx := dB.GetWriteDB().Begin()
    sqlStr := "INSERT INTO city(code, name) VALUES (?, ?),(?, ?)"
    vals := []interface{}{}

    vals = append(vals, "XX1", "Jakarta")
    vals = append(vals, "XX2", "Bandung")

    tx.Exec(sqlStr, vals)

    tx.Commit()

    return nil
}

But I got an error:

> Error 1136: Column count doesn't match value count at row 1 becuse i return wrong query
>
> INSERT INTO city(code, name) VALUES ('XX1','Jakarta','XX2','Bandung', %!v(MISSING)),(%!v(MISSING), %!v(MISSING))

If I use manual query it works:

tx.Exec(sqlStr, "XX1", "Jakarta", "XX2", "Bandung")

It will generate:

INSERT INTO city(code, name) VALUES ('XX1', 'Jakarta'),('XX2', 'Bandung')

The problem is how to make array interface to generate string like "XX1", "Jakarta", ...

Thanks for help.

If you want to pass elements of a slice to a function with variadic parameter, you have to use ... to tell the compiler you want to pass all elements individually and not pass the slice value as a single argument, so simply do:

tx.Exec(sqlStr, vals...)

This is detailed in the spec: Passing arguments to ... parameters.

Tx.Exec() has the signature of:

func (tx *Tx) Exec(query string, args ...interface{}) (Result, error)

So you have to pass vals.... Also don't forget to check returned error, e.g.:

res, err := tx.Exec(sqlStr, vals...)
if err != nil {
    // handle error
}