How to deploy a smart contract with Brownie on XDC Network

Overview

Python is one of the most versatile programming languages; from researchers running their test models to developers using it in heavy production environments, it has use cases in every possible technical field. Today’s guide will teach us about Brownie, a Python-based tool for writing and deploying smart contracts on XDC Network.

Prerequisites

• Python3 installed
• Text editor
• Command-line
• Love for brownies
• What is Brownie?

JavaScript-based libraries like XDC3.js, ethers.js, Truffle, and Hardhat dominate smart contract development. Python is a versatile, highly used language and can also be used for smart contracts/web3 development; web3.py is a compelling Python library that fulfills web3 needs. The Brownie framework is built on top of web3.py.

Brownies are small rectangular confectionery items loved by everyone, but the Brownie we are talking about today is a Python-based framework to develop and test smart contracts. Brownie has support for both Solidity and Vyper contracts, and it even provides contract testing via pytest.

To demonstrate the process of writing and deploying a smart contract with Brownie, we will use Brownie mixes which are template projects. Specifically, we will use a token mix, a template of the XRC-20 implementation.

Installing dependencies

This should return the version of python3 installed. If not installed, download and install it from the official Python website

Let us make a project directory before installing Brownie and make that project directory our current working directory.

Brownie is built on top of Python3, so we need it installed to work with Brownie; let us check if we have Python3 installed on our system. To do so, type the following in your terminal/cmd:

python3 -V

mkdir brownieDemo
cd brownieDemo

Now that you have installed Python3 on your system, let us install Brownie using pip, Python’s package manager. Pip is similar to what npm is for JavaScript. Type the following in your terminal/cmd:

pip3 install eth-brownie
## If the install failS, use the following command for better luck.
sudo pip3 install eth-brownie

To check if Brownie was installed correctly, type brownie in your terminal/cmd, and it should give the following output:

To get the token mix, type the following in your terminal/cmd:

brownie bake token

This will create a new directory token/ in our brownieDemo directory.

File Structure

First, let’s cd into the token directory:

cd token

Now, open the token directory in your text editor. Under the contracts/ folder, you will find Token.sol, which is our main contract; you can write your own contracts or modify this. Under the scripts/ folder, you will find the token.py python script; this script will be used to deploy the contract, and modifications are needed based on the contracts.

The contract is an XRC-20 contract; you can learn more about the XRC-20 standards and contracts in this guide on XRC-20 tokens.

We will deploy our contract on the XDC Apothem testnet instead of running our own node and setting up a dedicated RPC, and we will be using the public RPC:- https://erpc.apothem.network

Network and Account Set Up.

We need to set up the XDC APothem Network with Brownie. To do so, type the following in your terminal/cmd:

brownie networks add XDC Apothem Testnet host=https://erpc.apothem.network chainid=51

The next thing we need to do here is to create a new wallet using Brownie. To do so, type the following in your terminal/cmd. You will be asked to set up a password for your account.

brownie accounts generate testac

This will generate an account along with a mnemonic phrase and save it offline. The name testac is the name for our account. You can choose any name that you would like.

Note: Mnemonic phrases can be used to recover an account or import the account to other non-custodial wallets. The account you see in the image above was just created for this guide.

Copy the account address so that we can get some test XDC, which will be required to deploy our contract.

Getting test XDC

As our contract will be deployed on the Apothem testnet, we will require some Apothem test XDC to pay for the gas fee. Head over to the Apothem faucet at https://faucet.apothem.network paste your address in the field and change the address prefix from ox to xdc and click on “Send me test XDC”.

Deploying our contract

Before deploying the contract, we need to compile it using:

brownie compile

Now open the *scripts/*token.py in your text editor, and make the following changes:

#!/usr/bin/3

from brownie import Token, accounts

def main():
    acct = accounts.load('testac')
    return Token.deploy("Test Token", "TST", 18, 1e21, {'from': acct})   

Line 6: We added this line to import the testac account we created earlier and stored it in the acct variable.

Line 7: On this line, we edited the ‘From’: part to have our acct variable.

FINALLY, we will deploy our contract using the deployment script (scripts/token.py here):

brownie run token.py — network Apothem

Here is the TX hash for the contract which has been deployed on the Apothem Network https://explorer.apothem.network/txs/0xf573290954a3192e97a542c901c58d10b2f8f527299f8721957e06af678d5289#overview

Conclusion

So, today we learned brownies are good, but Brownie framework is the best. We learned how to import a Brownie-mix, add XDC Apothem Network, create an account, and compile and deploy a contract, and we used Brownie for the entire process!

If you have any questions, please feel free to post it on https://xdc.dev