Interagindo com contratos

No tutorial anterior aprendemos a se conectar com a blockchain Bywise. Agora para interagirmos com um smartcontract na rede da Bywise é muito simples.

Código completo aqui (opens in a new tab).

Vamos considerar o seguinte contrato.

import BywiseUtils, { StorageValue } from 'bywise-utils.js';
 
class StorageContract {
 
    value = new StorageValue('');
 
    setValue(newValue) {
        this.value.set(newValue);
    }
 
    getValue() { // @view
        return this.value.get();
    }
}
 
BywiseUtils.exportContract(new StorageContract());

Criamos o botão Try Connect que tenta realizar a conexão com carteira do usuário. Depois disso, nós buscamos algumas informações do endereço conectado.

const chain = 'mainnet'
const provider = new BywiseProvider(chain);
const contractAddress = 'BWS000000000000000000000000000000000000000000000'; // your contract address
 
const connect = async () => {
    const userInfo = await provider.connect();
 
    if (userInfo) {
        setConnect(true);
 
        updateValue(); // call update value
    }
}

Agora vamos ler o valor da variável do contrato.

const updateValue = async () => {
    const fullOutput = await provider.web3.contracts.readContract(chain, contractAddress, 'getValue', []);
    if (fullOutput.error) {
        alert(`error ${fullOutput.error}`);
    } else {
        const contractReturnValue = fullOutput.output;
        setValue(contractReturnValue);
    }
}

Agora vamos interagir com o contrato setando o valor para a variável value.

const setValueButton = async () => {
    const result = await provider.send({
        to: [contractAddress],
        amount: ['0'],
        type: TxType.TX_CONTRACT_EXE,
        data: [
            {
                method: 'setValue',
                inputs: [`I believe I can fly - ${Math.floor(Math.random() * 1000)}`],
            },
        ]
    });
    updateValue(); // call update value
}

Vamos ver o código completo.

import Head from 'next/head'
import styles from '../styles/Home.module.css'
import { useState } from 'react';
import BywiseProvider from '@bywise/provider';
import { TxType } from '@bywise/web3';
import { useRouter } from 'next/router';
 
const chain = 'testnet'
const provider = new BywiseProvider(chain);
const contractAddress = 'BWS1MC637abce1D5263e36FbBa6bCe77a01e764B4A65e1e68';
 
export default function Home() {
    const router = useRouter();
    const [connected, setConnect] = useState(false);
    const [value, setValue] = useState('');
 
    const connect = async () => {
    const userInfo = await provider.connect();
 
        if (userInfo) {
            setConnect(true);
 
            updateValue(); // call update update value
        }
    }
 
    const updateValue = async () => {
        const fullOutput = await provider.web3.contracts.readContract(chain, contractAddress, 'getValue', []);
        if (fullOutput.error) {
            alert(`error ${fullOutput.error}`);
        } else {
            const contractReturnValue = fullOutput.output;
            setValue(contractReturnValue);
        }
    }
 
    const setValueButton = async () => {
        const result = await provider.send({
            to: [contractAddress],
            amount: ['0'],
            type: TxType.TX_CONTRACT_EXE,
            data: [
                {
                    method: 'setValue',
                    inputs: [`I believe I can fly - ${Math.floor(Math.random() * 1000)}`],
                },
            ]
        });
        updateValue(); // call update update value
    }
 
    return (
        <div className={styles.container}>
            <Head>
                <title>Web3 Example</title>
                <meta name="description" content="Bywise web3 provider example" />
                <link rel="icon" href={`${router.basePath}/favicon.ico`} />
            </Head>
 
            <main className={styles.main}>
                <img className={styles.bywise_logo} src={`${router.basePath}/favicon.ico`} alt='Blockchain Bywise Logo' />
                <h1 className={styles.title}>
                  Welcome to <a target="_blank" href="https://bywise.org" rel="noopener noreferrer">Bywise</a>
                </h1>
 
                {connected && <>
                    <p className={styles.description}>
                        <span>
                            {'Contract Value: '}
                            <code className={styles.code}>"{value}"</code>
                        </span>
                    </p>
                </>}
 
                <div className={styles.grid} >
                    {connected && <>
                        <button className={styles.card} onClick={setValueButton}>
                            <h2>Update Value 🔥</h2>
                        </button>
                    </>}
 
                    {!connected && <button className={styles.card} onClick={connect}>
                        <h2>Connect Wallet 🚀</h2>
                    </button>}
                </div>
            </main>
 
            <footer className={styles.footer}>
                <a
                  href="https://develblockchain.com"
                  target="_blank"
                  rel="noopener noreferrer"
                >
                    Powered by{' '}
                    <span className={styles.logo}>
                        <img src={`${router.basePath}/devel.svg`} alt='Devel Blockchain Logo' height={40} />
                    </span>
                </a>
            </footer>
        </div>
    )
}

Introdução