Auto Increment in PostGres

Sol will exclude zero value fields marked omitempty during INSERT. This behavior can be used to intelligently manage both PostGres auto increment columns and other values set on the database. An example:

package main

import (
	"log"

	"github.com/aodin/sol"
	"github.com/aodin/sol/postgres"
	"github.com/aodin/sol/types"
)

var Things = postgres.Table("things",
	sol.Column("id", postgres.Serial()),
	sol.Column("name", types.Varchar().Limit(32).NotNull()),
	sol.PrimaryKey("id"),
)

type Thing struct {
	ID   uint64 `db:",omitempty"`
	Name string
}

func (thing *Thing) Save(conn sol.Conn) {
	conn.Query(Things.Insert().Values(thing).Returning(), thing)
}

func NewThing(name string) (thing Thing) {
	thing.Name = name
	return
}

func main() {
	conn, err := sol.Open("postgres", <credentials>)
	if err != nil {
		log.Fatal(err)
	}

	conn.Must().Query(Things.Create().IfNotExists().Temporary())
	gopher := NewThing("Gopher")
	gopher.Save(conn)
	log.Printf("%+v", gopher) // {ID:1 Name:Gopher}
}

The Save method will produce the following SQL when an ID is zero:

INSERT INTO things (name) VALUES ($1) RETURNING things.id, things.name