Golang : GORM read from database example



Tags : golang gorm mysql mariadb pagination

Just a simple tutorial on how to use GORM(Golang Object Relational Map) to connect to a MySQL/MariaDB database and read data from it.

Here you go!

 package main

 import (
 "fmt"
 _ "github.com/go-sql-driver/mysql"
 "github.com/jinzhu/gorm"
 "time"
 )

 // Activities table SQL :
 // id bigint(20)  AUTO_INCREMENT
 // username varchar(50)
 // created_on  timestamp
 // action char(1)
 // description varchar(300)
 // visibility  char(1)

 type Activities struct {
 Id int `sql:"AUTO_INCREMENT"`
 Username string `sql:"varchar(50);unique"`
 Created_On  time.Time
 Action string `sql:"type:char(1)"`
 Description string `sql:"type:varchar(300)"`
 Visibility  string `sql:"type:char(1)"`
 }

 func main() {

 dbConn, err := gorm.Open("mysql", "username:password@tcp(xx.xxx.xxx.xxx:3306)/database_name?charset=utf8&parseTime=true")

 if err != nil {
 fmt.Println(err)
 }

 // init
 dbConn.DB()
 dbConn.DB().Ping()
 dbConn.DB().SetMaxIdleConns(10)
 dbConn.DB().SetMaxOpenConns(100)

 activity := Activities{} // a record

 // get first record
 dbConn.First(&activity)

 fmt.Println(activity)

 fmt.Println("------------------------------")
 // get all records
 activities := []Activities{} // a slice

 //dbConn.Find(&activities)
 //fmt.Println(activities)


 // get records from record offset 1 to 10
 // useful for pagination purpose! - just need to calculate the offset and limit dynamically

 dbConn.Limit(10).Order("id asc").Find(&activities).Offset(1).Order("id asc").Find(&activities)

 for _, v := range activities {
 fmt.Println("Id : ", v.Id)
 fmt.Println("Username : ", v.Username)
 fmt.Println("Created On : ", v.Created_On)
 fmt.Println("Action : ", v.Action)
 fmt.Println("Desription : ", v.Description)
 fmt.Println("Visibility : ", v.Visibility)
 }

 }

NOTE : Without the &parseTime=true parameter in the dbConn configuration. Your driver will have problem reading(scanning) and translating the SQL timestamp.

References :

https://en.wikipedia.org/wiki/Object-relational_mapping

https://www.socketloop.com/tutorials/golang-connect-to-database-mysql-mariadb-server

https://github.com/jinzhu/gorm

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  See also : Golang : Connect to database (MySQL/MariaDB) server



Tags : golang gorm mysql mariadb pagination

By Adam Ng

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