BNB Smart Chain: BEP-1155 contract with Truffle & OpenZeppelin

With Chainstack, create a public chain project.

With Chainstack, join the BNB Smart Chain testnet.

With Chainstack, access your BNB Smart Chain node credentials.

With OpenZeppelin, create a BEP-1155 contract.

With Truffle, compile and deploy the contract through your BNB Smart Chain node.

In your contract directory, initialize Truffle:

truffle init

This will generate the Truffle boilerplate structure:

.
├── contracts
│   └── .gitkeep
├── migrations
│   └── .gitkeep
├── test
│   └── .gitkeep
└── truffle-config.js

Go to the contracts directory. In the directory, create your BEP-1155 contract: BNBSmartChain1155.sol.

//SPDX-License-Identifier: MIT
pragma solidity ^0.8;

import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol";

contract BNBSmartChain1155 is ERC1155 {
  uint256 public constant FUNGIBLE = 0;
  uint256 public constant NON_FUNGIBLE = 1;

  constructor() ERC1155("JSON_URI") {
    _mint(msg.sender, FUNGIBLE, 100, "");
    _mint(msg.sender, NON_FUNGIBLE, 1, "");
  }
}

The contract implementation is the following:

• The contract uses OpenZeppelin audited ERC-1155 contract templates.
• The contract creates two tokens: 100 fungible units of the currency called FUNGIBLE and 1 non-fungible unit called NON-FUNGIBLE. In the BEP-1155 standard, setting a token issuance to 1 makes it non-fungible.
• The contract also has JSON_URI which is a locator for the metadata of your tokens hosted externally. For example, <https://token-cdn-domain/{id}.json>. See EIP-1155 for details.

Create 2_deploy_contracts.js in the migrations directory.

module.exports = function(deployer) {
var BNBSmartChain1155 = artifacts.require("./BNBSmartChain1155.sol");
  deployer.deploy(BNBSmartChain1155);
};

This will create the contract deployment instructions for Truffle.

Install HDWalletProvider.

HDWalletProvider is Truffle’s separate npm package used to sign transactions.

Run:

npm install @truffle/hdwallet-provider

Edit truffle-config.js to add:

• HDWalletProvider

• Your BNB Smart Chain node access and credentials

• Your BNB Smart Chain account that you will use to deploy the contract

  JavaScript

  Copy

  const HDWalletProvider = require("@truffle/hdwallet-provider");
  const private_key = 'PRIVATE_KEY';
  
  module.exports = {
    networks: {
      testnet: {
        provider: () => new HDWalletProvider(private_key, "YOUR_CHAINSTACK_ENDPOINT"),
        network_id: 97,
        confirmations: 3,
        timeoutBlocks: 200,
        skipDryRun: true
    }
   },
  
   compilers: {
     solc: {
     version: "0.8.2",
     }
   }
  };
  

where

• testnet — any network name that you will pass to the truffle migrate --network command.
• HDWalletProvider — Truffle’s custom provider to sign transactions.
• PRIVATE_KEY — the private key of your BNB Smart Chain account that will deploy the contract. The account must have enough BNB funds to run the deployment. See also BNB Smart Chain Faucet.
• YOUR_CHAINSTACK_ENDPOINT — your Chainstack node HTTPS endpoint. See also View node access and credentials and BNB Smart Chain tooling.
• network_id — the network ID of the BNB Smart Chain network: mainnet is 56, testnet is 97.
• solc — the Solidity compiler version that Truffle must use. OpenZeppelin contracts have a higher version Solidity compiler requirement than the default Truffle installation, hence you must provide a specific compiler version.

Run:

truffle migrate --network testnet

This will engage 2_deploy_contracts.js and deploy the contract to the BNB Smart Chain testnet as specified in truffle-config.js.

Install Truffle Flattener.

Run:

npm install truffle-flattener

Flatten the contract.

In the contracts directory, run:

npx truffle-flattener BNBSmartChain1155.sol > FlatBNBSmartChain1155.sol

Clean up the licensing information.

The flattened contract will have the same licensing note imported from each of the files. Multiple licensing notes in one file break the BscScan verification, so you have to leave one licensing note for the entirety of the flattened contract.

The easiest way to clean up is to search for the SPDX mentions in the file and remove all of them except for the very first one.

Go to BscScan testnet.

Find your deployed contract. The address of your contract should have been printed by Truffle at the end of the deployment in the contract address field.

On the contract page on BscScan, click Contract > Verify and Publish.

In Compiler Type, select Solidity (Single file).

In Compiler Version, select v0.8.2. This is the version this tutorial used to compile the contract.

Click Continue.

Keep the Optimization option set to No as Truffle does not use optimization by default.

Paste the entirety of your flattened .sol contract in the Enter the Solidity Contract Code below field.

Click Verify and Publish.

On BscScan, on your contract, click Contract.

Click Read Contract.

Scroll to the balanceOf field.

In the account field, provide the address of the account you used to deploy the contract.

In the id field, put 0 to check your fungible balance and put 1 to check your non-fungible balance.