Golang : GORM read from database example
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
See also : Golang : Connect to database (MySQL/MariaDB) server
By Adam Ng
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