Simple Voting Smart Contract

This repository provides a comprehensive guide to creating, building, deploying, and interacting with a simple voting smart contract on the MultiversX blockchain.

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Why MultiversX?

MultiversX is a high-performance blockchain designed for scalability, efficiency, and low-cost transactions, making it ideal for smart contract development. Here's why:

Performance

• High Throughput: Handles up to 15,000 transactions per second (TPS) with transaction costs as low as $0.001.
• Scalability: Adaptive State Sharding enables the network to scale beyond 100,000 TPS as it grows.
• Tested Efficiency: Reached up to 263,000 TPS on the testnet.

Developer Ecosystem

• Comprehensive Tools: Includes an IDE, a Rust-based framework, and debugging utilities.
• Incentives: Developers earn 30% of gas fees for contract execution.
• WASM Compatibility: Allows the use of WebAssembly (WASM) for diverse programming languages.

Rust Framework

Rust offers a robust environment for developing efficient and secure smart contracts with minimal gas costs.

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Getting Started

Step 1: Install pipx

pipx is the recommended tool for installing the MultiversX CLI (mxpy).

Ubuntu & Windows WSL

sudo apt update
sudo apt install pipx
pipx ensurepath

macOS

brew install pipx
pipx ensurepath

Verify installation:

pipx --version

Step 2: Install mxpy

Install the MultiversX CLI for blockchain interactions and smart contract management:

pipx install multiversx-sdk-cli --force

Step 3: Install Rust

Rust is required to compile smart contracts.

Ubuntu & Windows WSL

sudo apt install build-essential pkg-config libssl-dev

macOS

xcode-select --install

Install Rust via mxpy:

mxpy deps install rust --overwrite

Verify installation:

mxpy --version
rustup show

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Creating a New Smart Contract Project

Initialize a new smart contract project:

sc-meta new --template empty --name simple-voting

Verify the project setup:

cargo check

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Building the Smart Contract

Compile the smart contract into WebAssembly (WASM) bytecode:

sc-meta all build

This generates an output directory containing:

output/
├── simple-voting.abi.json
├── simple-voting.imports.json
├── simple-voting.mxsc.json
└── simple-voting.wasm

Key Outputs:

• simple-voting.wasm: Compiled bytecode for deployment.
• simple-voting.abi.json: ABI for interacting with the contract.

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Deploying the Smart Contract

Deployment to the Devnet

Define the deployment arguments in deploy_arguments.json:

[
  "What is your favorite programming language?", 
  ["Rust", "Python", "JavaScript", "C++"]
]

Deploy the contract:

mxpy --verbose contract deploy \
  --recall-nonce \
  --bytecode="./output/simple-voting.wasm" \
  --proxy=https://devnet-gateway.multiversx.com \
  --abi ./output/simple-voting.abi.json \
  --arguments-file ./deploy_arguments.json \
  --gas-limit 500000000 \
  --keyfile="./<your-wallet-keyfile>.json" \
  --send

Replace <your-wallet-keyfile>.json with your wallet keyfile name. Note the contract address after successful deployment.

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Upgrading the Smart Contract

To upgrade a deployed contract:

1. Build the updated contract:

   sc-meta all build

2. Deploy the upgraded bytecode:

   mxpy contract upgrade erd1<your-contract-address> \
     --bytecode ./output/simple-voting.wasm \
     --proxy=https://devnet-gateway.multiversx.com \
     --chain D \
     --recall-nonce \
     --gas-limit 5000000 \
     --keyfile="./<your-wallet-keyfile>.json" \
     --send

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Interacting with the Smart Contract

Querying the Contract

Example: Fetch the current poll question.

mxpy contract query erd1<your-contract-address> \
  --proxy https://devnet-gateway.multiversx.com \
  --function getPollQuestion

Voting Example

Cast a vote for an option (e.g., Rust):

mxpy contract call erd1<your-contract-address> \
  --function vote \
  --arguments str:Rust \
  --proxy https://devnet-gateway.multiversx.com \
  --keyfile "./<your-wallet-keyfile>.json" \
  --send

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Best Practices

1. Secure Your Wallet: Keep your wallet keyfile safe and backed up.
2. Optimize Gas Usage: Write efficient smart contract code to reduce gas costs.
3. Test Thoroughly: Test your contract extensively on the devnet before deploying to the mainnet.