trc21-exchange-wallet-integration.md

description
This tutorial will walk through integrating TRC2 tokens to applications (e.g., wallet, exchange)

TRC25 Exchange/Wallet integration

Prerequisites

Contract ABI: IVRC25.json

Contract Interface: IVRC25.sol

interface IVRC25 {
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    event Fee(address indexed from, address indexed to, address indexed issuer, uint256 value);

    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint256);
    function balanceOf(address owner) external view returns (uint256);
    function issuer() external view returns (address);
    function allowance(address owner, address spender) external view returns (uint256);
    function estimateFee(uint256 value) external view returns (uint256);
    function transfer(address recipient, uint256 value) external returns (bool);
    function approve(address spender, uint256 value) external returns (bool);
    function transferFrom(address from, address to, uint256 value) external  returns (bool);
}

Users are recommended to refer to the TRC25 Specification for more details about the TRC25 token standard.

Follow the steps below to interact with the smart contract by using the Web3 library and Node.

Initialize Web3 provider

As a first step, we need to initialize a Web3 provider by connecting to TomoChain Full node RPC endpoint.

Look at the TomoChain Networks page to get more information of the TomoChain Testnet/Mainnet RPC network.

const Web3 = require('web3')
const web3 = new Web3('https://rpc.tomochain.com')
const chainId = 88

Unlock wallet

Unlock the wallet before interacting with TRC25 token contracts

Example

// Unlock wallet by private key
const account = web3.eth.accounts.privateKeyToAccount(pkey)
const holder = account.address
web3.eth.accounts.wallet.add(account)
web3.eth.defaultAccount = holder

Initialize Web3 TRC25 Contract

const trc25Abi = require('./IVRC25.json')
const address = '[enter_your_contract_address]'
const trc25 = new web3.eth.Contract(trc25Abi,
        address, {gasPrice: 250000000, gas: 2000000 })

Note: Get IVRC21.json here.

Check balance

Call function balanceOf() from TRC25 contract to check the token balance for an address.

Example

trc25.methods.balanceOf(holder).call()
.then((result) => {
    console.log(result)
}).catch(e => console.log(e))

Estimate fee

Before sending tokens, we need to check TX fee by calling estimateFee function in TRC25 smart contract.

Example

trc25.methods.estimateFee().call()
.then((result) => {
    console.log(result)
}).catch(e => console.log(e))

Note: this fee is the amount of the token that needs to be paid to send the TRC25 token applied to TomoZ

Transfer token

The Token holder needs to call function transfer to send token to an address.

Example

// send 500000000000000000000 tokens to this address (e.g decimals 18)
const to = "0xf8ac9d5022853c5847ef75aea0104eed09e5f402"
trc25.methods.transfer(to, '500000000000000000000').send({
    from: holder,
    gas: 2000000,
    gasPrice: 250000000,
    chainId: chainId
})
.then((result) => {
    console.log(result)
}).catch(e => console.log(e))

Checking TomoZ

Call getTokenCapacity to 0x8c0faeb5c6bed2129b8674f262fd45c4e9468bee. If the return value > 0, the token has successfully been enabled by the TomoZ protocol.