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Example code redeeming BPros
In the following example we will learn how to:
  • Get the maximum amount of BPRO available to redeem.
  • Get BPRO balance of an account.
  • Redeem BPROs.
We will use truffle and testnet network.
First we create a new node project.
mkdir example-redeem-bpro
cd example-redeem-bpro
npm init
Let's add the necessary dependencies to run the project.
npm install --save web3
Example
const Web3 = require('web3');
//You must compile the smart contracts or use the official ABIs of the repository
const MocAbi = require('../../build/contracts/MoC.json');
const MoCStateAbi = require('../../build/contracts/MoCState.json');
const BProTokenAbi = require('../../build/contracts/BProToken.json');
const truffleConfig = require('../../truffle');
/**
* Get a provider from truffle.js file
* @param {String} network
*/
const getDefaultProvider = network =>
truffleConfig.networks[network].provider || truffleConfig.networks[network].endpoint;
/**
* Get a gasPrice from truffle.js file
* @param {String} network
*/
const getGasPrice = network => truffleConfig.networks[network].gasPrice || 60000000;
/**
* Get a new web3 instance from truffle.js file
*/
const getWeb3 = network => {
const provider = getDefaultProvider(network);
return new Web3(provider, null, {
transactionConfirmationBlocks: 1
});
};
const web3 = getWeb3('rskTestnet');
const gasPrice = getGasPrice('rskTestnet');
//Contract addresses on testnet
const mocContractAddress = '<contract-address>';
const mocInrateAddress = '<contract-address>';
const mocStateAddress = '<contract-address>';
const bproTokenAddress = '<contract-address>';
const execute = async () => {
web3.eth.defaultGas = 2000000;
/**
* Loads an specified contract
* @param {ContractABI} abi
* @param {String} contractAddress
*/
const getContract = async (abi, contractAddress) => new web3.eth.Contract(abi, contractAddress);
// Loading moc contract
const moc = await getContract(MocAbi.abi, mocContractAddress);
if (!moc) {
throw Error('Can not find MoC contract.');
}
// Loading mocState contract. It is necessary to compute absolute max BPRO
const mocState = await getContract(MoCStateAbi.abi, mocStateAddress);
if (!mocState) {
throw Error('Can not find MoCState contract.');
}
// Loading BProToken contract. It is necessary to compute user balance
const bproToken = await getContract(BProTokenAbi.abi, bproTokenAddress);
if (!bproToken) {
throw Error('Can not find BProToken contract.');
}
const [from] = await web3.eth.getAccounts();
const redeemBpro = async (bproAmount, vendorAccount) => {
const weiAmount = web3.utils.toWei(bproAmount, 'ether');
console.log(`Calling redeem Bpro with account: ${from} and amount: ${weiAmount}.`);
moc.methods
.redeemBProVendors(weiAmount, vendorAccount)
.send({ from, gasPrice }, function(error, transactionHash) {
if (error) console.log(error);
if (transactionHash) console.log('txHash: '.concat(transactionHash));
})
.on('transactionHash', function(hash) {
console.log('TxHash: '.concat(hash));
})
.on('receipt', function(receipt) {
console.log(receipt);
})
.on('error', console.error);
};
const getAbsoluteMaxBpro = await mocState.methods.absoluteMaxBPro().call();
const userAmount = await bproToken.methods.balanceOf(from).call();
console.log('=== Max amount of BPro to redeem: ', getAbsoluteMaxBpro.toString());
console.log('=== User BPro Balance: ', userAmount.toString());
const bproAmount = '0.00001';
const vendorAccount = '<vendor-address>';
// Call redeem
await redeemBpro(bproAmount, vendorAccount);
};
execute()
.then(() => console.log('Completed'))
.catch(err => {
console.log('Error', err);
});
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