ivoras / pg

PostgreSQL ORM for Golang with focus on PostgreSQL features and performance

PostgreSQL client for Golang

Features:

• Basic types: integers, floats, string, bool, time.Time, net.IP, net.IPNet.
• sql.NullBool, sql.NullString, sql.NullInt64, sql.NullFloat64 and pg.NullTime.
• sql.Scanner and sql/driver.Valuer interfaces.
• Structs, maps and arrays are marshalled as JSON by default.
• PostgreSQL multidimensional Arrays using array tag and Array wrapper.
• Hstore using hstore tag and Hstore wrapper.
• All struct fields are nullable by default and zero values (empty string, 0, zero time) are marshalled as SQL NULL. sql:",notnull" tag is used to reverse this behaviour.
• Transactions.
• Prepared statements.
• Notifications using LISTEN and NOTIFY.
• Copying data using COPY FROM and COPY TO.
• Timeouts.
• Automatic connection pooling.
• Queries retries on network errors.
• Working with models using ORM and SQL.
• Scanning variables using ORM and SQL.
• SelectOrInsert using on-conflict.
• INSERT ... ON CONFLICT DO UPDATE using ORM.
• Bulk/batch inserts and updates.
• Common table expressions using WITH and WrapWith.
• CountEstimate using EXPLAIN to get estimated number of matching rows.
• HasOne, BelongsTo, HasMany and ManyToMany.
• Creating tables from structs.
• Pagination and URL filters helpers.
• Migrations.
• Sharding.

Get Started

• Wiki
• API docs
• Examples

Look & Feel

package pg_test

import (
   "fmt"

   "github.com/go-pg/pg"
   "github.com/go-pg/pg/orm"
)

type User struct {
   Id     int64
   Name   string
   Emails []string
}

func (u User) String() string {
   return fmt.Sprintf("User<%d %s %v>", u.Id, u.Name, u.Emails)
}

type Story struct {
   Id       int64
   Title    string
   AuthorId int64
   Author   *User
}

func (s Story) String() string {
   return fmt.Sprintf("Story<%d %s %s>", s.Id, s.Title, s.Author)
}

func ExampleDB_Model() {
   db := pg.Connect(&pg.Options{
      User: "postgres",
   })

   err := createSchema(db)
   if err != nil {
      panic(err)
   }

   user1 := &User{
      Name:   "admin",
      Emails: []string{"admin1@admin", "admin2@admin"},
   }
   err = db.Insert(user1)
   if err != nil {
      panic(err)
   }

   err = db.Insert(&User{
      Name:   "root",
      Emails: []string{"root1@root", "root2@root"},
   })
   if err != nil {
      panic(err)
   }

   story1 := &Story{
      Title:    "Cool story",
      AuthorId: user1.Id,
   }
   err = db.Insert(story1)
   if err != nil {
      panic(err)
   }

   // Select user by primary key.
   user := User{Id: user1.Id}
   err = db.Select(&user)
   if err != nil {
      panic(err)
   }

   // Select all users.
   var users []User
   err = db.Model(&users).Select()
   if err != nil {
      panic(err)
   }

   // Select story and associated author in one query.
   var story Story
   err = db.Model(&story).
      Column("story.*", "Author").
      Where("story.id = ?", story1.Id).
      Select()
   if err != nil {
      panic(err)
   }

   fmt.Println(user)
   fmt.Println(users)
   fmt.Println(story)
   // Output: User<1 admin [admin1@admin admin2@admin]>
   // [User<1 admin [admin1@admin admin2@admin]> User<2 root [root1@root root2@root]>]
   // Story<1 Cool story User<1 admin [admin1@admin admin2@admin]>>
}

func createSchema(db *pg.DB) error {
   for _, model := range []interface{}{&User{}, &Story{}} {
      err := db.CreateTable(model, &orm.CreateTableOptions{
         Temp: true,
      })
      if err != nil {
         return err
      }
   }
   return nil
}

See also

• Golang msgpack
• Golang message task queue