Go programming language, also known as Golang, is a powerful language designed to create efficient and scalable software. It is widely used in building distributed systems, cloud applications, and networking applications. With the rise of blockchain technology, Go has become a popular language for building decentralized applications (DApps).

In this tutorial, we will walk you through the process of building a decentralized application using Go programming language. By the end of this tutorial, you will have a good understanding of how to build DApps using Go.


Setting up the environment

To start building DApps with Go, you need to set up your development environment. You need to have Go installed on your computer. You can download and install Go from the official Go website. Once you have installed Go, you can check the installation by running the following command in your terminal: 

go version

This command should print the version of Go installed on your computer. If you see an error message, it means that Go is not installed correctly, and you need to reinstall it.


Choosing a blockchain platform

To build a decentralized application, you need to choose a blockchain platform. Ethereum is the most popular blockchain platform for building DApps, but there are other options such as Polkadot, Binance Smart Chain, and Cardano.

In this tutorial, we will use Ethereum as our blockchain platform. To interact with the Ethereum blockchain, you need to install a client. There are several Ethereum clients available, such as Geth, Parity, and OpenEthereum. In this tutorial, we will use Geth.


Writing the smart contract

A smart contract is a self-executing contract that contains the rules and regulations of an agreement between two parties. In the context of DApps, smart contracts are used to implement the business logic of the application.

To write a smart contract in Go, you need to use a framework called Solidity. Solidity is a programming language specifically designed for writing smart contracts on the Ethereum blockchain.

Here is an example of a simple smart contract written in Solidity:

pragma solidity ^0.8.0;

contract HelloWorld {
    string public message;

    constructor() {
        message = "Hello, World!";
    }

    function setMessage(string memory newMessage) public {
        message = newMessage;
    }
}

This smart contract sets a message to "Hello, World!" and provides a function to update the message.


Compiling the smart contract

Once you have written your smart contract, you need to compile it into bytecode. To compile the smart contract, you need to use a Solidity compiler. You can use the Solidity compiler available on the Remix IDE or install the Solidity compiler on your computer.

To compile the smart contract using the Solidity compiler on your computer, you can use the following command: 

solc --abi --bin HelloWorld.sol -o build

This command compiles the smart contract and generates two files: the bytecode and the Application Binary Interface (ABI).


Deploying the smart contract

Once you have compiled the smart contract, you need to deploy it to the Ethereum blockchain. To deploy the smart contract, you need to interact with the Ethereum client.

Here is an example of how to deploy the smart contract using Geth:

1. Start Geth with the following command: 

geth --rinkeby --rpc --rpcapi eth,net,web3

This command starts Geth with the Rinkeby test network, enables the RPC interface, and allows the use of the eth, net, and web3 APIs.

2. Open a new terminal window and run the following command to connect to the Geth client:

geth attach

This command connects to the Geth client using the IPC protocol.

3. Unlock your Ethereum account by running the following command: 

personal.unlockAccount(ADDRESS, PASSWORD, UNLOCK_DURATION)

Replace ADDRESS with the address of your Ethereum account, PASSWORD with the password of your Ethereum account, and UNLOCK_DURATION with the duration (in seconds) for which you want to unlock your account.

4. Load the compiled smart contract by running the following command: 

var helloWorldContract = web3.eth.contract(ABI).new({data: BYTECODE, from: ADDRESS, gas: GAS_LIMIT})

Replace ABI with the ABI of your smart contract, BYTECODE with the bytecode of your smart contract, ADDRESS with the address of your Ethereum account, and GAS_LIMIT with the gas limit for deploying the smart contract.

5. Wait for the smart contract to be deployed. You can check the status of the deployment by running the following command: 

helloWorldContract.address

This command returns the address of the deployed smart contract.


Building the front-end

Now that you have deployed the smart contract, you need to build the front-end of your DApp. You can use any front-end framework of your choice, such as React, Vue.js, or Angular.

Here is an example of a simple front-end built using React:

import React, { useState, useEffect } from 'react';
import HelloWorldContract from './contracts/HelloWorld.json';
import getWeb3 from './getWeb3';

function App() {
  const [message, setMessage] = useState('Loading...');
  const [web3, setWeb3] = useState(null);
  const [contract, setContract] = useState(null);

  useEffect(() => {
    async function init() {
      const web3 = await getWeb3();
      const networkId = await web3.eth.net.getId();
      const contract = new web3.eth.Contract(
        HelloWorldContract.abi,
        HelloWorldContract.networks[networkId].address,
      );
      const message = await contract.methods.message().call();
      setWeb3(web3);
      setContract(contract);
      setMessage(message);
    }
    init();
  }, []);

  async function updateMessage(newMessage) {
    const accounts = await web3.eth.getAccounts();
    await contract.methods.setMessage(newMessage).send({ from: accounts[0] });
    const message = await contract.methods.message().call();
    setMessage(message);
  }

  return (
    <div>
      <h1>{message}</h1>
      <input type="text" onChange={event => updateMessage(event.target.value)} />
    </div>
  );
}

export default App;

This front-end displays the message of the smart contract and provides a text input to update the message.

Testing the DApp

Now that you have built the front-end, you can test your DApp. You can start by running your front-end locally using a development server. You can use a package like create-react-app to create a development server.

Once your front-end is running, you can interact with your DApp by opening it in a web browser. You can test the functionality of your DApp by updating the message and verifying that the message has been updated in the smart contract.


Conclusion

In this tutorial, we have shown you how to build a decentralized application using Go programming language. We have covered the basics of writing a smart contract, compiling and deploying the smart contract, and building a front-end for the DApp. We hope that this tutorial has given you a good understanding of how to build DApps using Go and has inspired you to explore the possibilities of building decentralized applications.