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Posted By hunterlong —

MySQL to Struct in Go Language


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Here’s an example of creating a new struct object from a MySQL query. The function below will fetch a user based on the userId (int) submitted. Look at the bottom of this post to see how to Fetch an array of each user in database. I have also include a MySQL dump of the Users table.

User struct

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type User struct {
	Id            int       `json:"id"`
	Name          string    `json:"name"`
	Email         string    `json:"email"`
}

Fetching User Function (creating User) (Table: users – Columns: id,name,email)

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// import "database/sql"
 
var db *sql.DB
 
func main() {
   // replace the information below to match your MySQL login and database
   db, _ = sql.Open("mysql", "root:password@tcp(localhost:3306)/mydatabase")
}
 
func FetchUser(userId int) User {
	rows := db.QueryRow("SELECT id,email,name FROM users WHERE id=?", userId)
	var id int
	var name, email string
	var user User
	err := rows.Scan(&id, &email, &name)
	if err != nil {
		if err == sql.ErrNoRows {
                       // no such user id
		} else {
			panic(err)
		}
	} else {
		user = User{Id: id, Name: name, Email: email}
	}
	return user
}

Using the function in script

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thisUser := FetchUser(5)
fmt.Println(thisUser.Email)

Example of Fetching All Users

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func FetchAllUsers() []User {
	rows, _ := db.Query("SELECT id,email,name FROM users")
	var id int
	var name, email string
	var users []User
 
	for rows.Next() {
		err := rows.Scan(&id, &name, &email)
		if err != nil { /* error handling */}
		users = append(users, User{Id: id, Email: email, Name: name})
	}
 
	return users
}

Print out how many users are in database

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fmt.Println("Total amount of Users: ", len(FetchAllUsers()))

MySQL Dump of Users table

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CREATE TABLE IF NOT EXISTS `users` (
  `id` int(11) NOT NULL,
  `email` text NOT NULL,
  `name` text NOT NULL
) ENGINE=MyISAM AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;
 
INSERT INTO `users` (`id`, `email`, `name`) VALUES
(5, 'info@domain.com', 'Example User'),
(6, 'info@anotherdomain.com', 'Another User');
 
ALTER TABLE `users`
  ADD PRIMARY KEY (`id`);
 
ALTER TABLE `users`
  MODIFY `id` int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=7;

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