Demo Project Setup

In this lesson, we'll create a simple project that connects to a MySQL database using Golang. You will learn how to create a database, set up a table, insert sample data, and build a Golang application that connects to the database and registers HTTP routes.

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Step 1: Initial Golang File Overview

Begin by creating a basic Golang file. The snippet below includes the necessary imports and a placeholder function for error checking:

package main

import (
    "database/sql"
    "fmt"
    _ "github.com/go-sql-driver/mysql"
    "log"
)

func checkError(e error) {
    // Implement error handling as needed
}

Desktop/kodekloud/learn via 🐹 v1.19.3

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Step 2: Database Setup in MySQL

First, create a database named Inventory. Follow these steps:

1. Log in to MySQL:

   mysql -u root -p
   

2. In the MySQL shell, create the database:

   create database inventory;
   -- Query OK, 1 row affected (0.01 sec)
   

3. Switch to the new database and create a table named Products with the following columns:

   • id: An integer, not null and auto-incremented.
   • name: A non-null varchar field.
   • quantity: An integer.
   • price: A float with precision.

   Execute the following SQL commands:

   mysql> use inventory;
   Database changed
   
   mysql> create table products(
       ->   id int NOT NULL AUTO_INCREMENT,
       ->   name varchar(255) NOT NULL,
       ->   quantity int,
       ->   price float(10,7),
       ->   PRIMARY KEY(id)
       -> );
   Query OK, 0 rows affected, 1 warning (0.01 sec)
   
   mysql> insert into products values(1, "chair", 100, 200.00);
   Query OK, 1 row affected (0.00 sec)
   
   mysql> insert into products values(2, "desk", 800, 600.00);
   Query OK, 1 row affected (0.00 sec)
   
   mysql> select * from products;
   +----+-------+----------+---------------+
   | id | name  | quantity | price         |
   +----+-------+----------+---------------+
   |  1 | chair |      100 | 200.0000000   |
   |  2 | desk  |      800 | 600.0000000   |
   +----+-------+----------+---------------+
   2 rows in set (0.00 sec)
   

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Step 3: Project Directory and Module Initialization

Set up your workspace by creating a new project directory called my-inventory. Then, initialize a new Go module and create the main application file.

cd ..
~/Desktop/kodekloud
mkdir my-inventory
cd my-inventory

Initialize the module and create the app file:

go mod init example.com/my-inventory
# go: creating new go.mod: module example.com/my-inventory
touch app.go

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Step 4: Application Structure and Database Initialization

Open the app.go file in your preferred IDE. This file will hold application variables such as the HTTP router, database instance, and methods for setting up routes.

1. Define the Package and App Struct

   Start by declaring the package and defining an App struct that stores pointers to the HTTP router and the SQL database:

   package main
   
   import (
       "database/sql"
       "fmt"
       "log"
       "net/http"
   
       "github.com/gorilla/mux"
       _ "github.com/go-sql-driver/mysql"
   )
   
   type App struct {
       Router *mux.Router
       DB     *sql.DB
   }
   

2. Create a Constants File for Database Configuration

   For better organization, create a file named constants.go that will store your database configuration details:

   package main
   
   const DbName = "inventory"
   const DbUser = "root"
   const DbPassword = "Priyanka#123"
   

3. Implement the Initialize Method

   This method constructs the connection string, opens a MySQL connection, and initializes the HTTP router:

   func (app *App) Initialize() error {
       connectionString := fmt.Sprintf("%v:%v@tcp(127.0.0.1:3306)/%v", DbUser, DbPassword, DbName)
   
       var err error
       app.DB, err = sql.Open("mysql", connectionString)
       if err != nil {
           return err
       }
   
       app.Router = mux.NewRouter().StrictSlash(true)
       return nil
   }
   

4. Create the Run Method

   Define the Run method to start the HTTP server. This method listens on a specified address and uses log.Fatal to report any server startup errors:

   func (app *App) Run(address string) {
       log.Fatal(http.ListenAndServe(address, app.Router))
   }
   

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Step 5: Main Function and Route Handling

Create a main.go file, which will serve as the application's entry point.

1. Set Up the Main Function

   Initialize the App, set up your HTTP routes, and run the server on a specified address (e.g., "localhost:10000"):

   package main
   
   func main() {
       app := App{}
       if err := app.Initialize(); err != nil {
           log.Fatal(err)
       }
   
       // Register HTTP routes.
       app.handleRoutes()
   
       // Start the server on localhost at port 10000.
       app.Run("localhost:10000")
   }
   

2. Register HTTP Routes

   Define the route registration method on the App struct. Here, a simple GET route for /products is registered, which is handled by the getProducts function:

   func (app *App) handleRoutes() {
       app.Router.HandleFunc("/products", getProducts).Methods("GET")
   }
   

   Note

   Remember to implement the getProducts handler to process HTTP GET requests for the /products route based on your application needs.

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Summary

In this lesson, we covered the following:

• Created a MySQL database and a Products table with sample data.
• Set up a new Golang module and organized the project into multiple files.
• Built an App struct to encapsulate the database connection and HTTP router.
• Implemented the Initialize and Run methods to manage the MySQL connection and start the HTTP server.
• Registered a sample route for fetching products.

This structured approach lays the foundation for further developing your application with expanded routing and enhanced database operations.