Overview

A Contract object is a meta-class, which communicates with a deployed smart contract on the blockchain and provides a simple JavaScript interface to call methods, send transactions, and query historic logs.

Smart contracts only exist on the Quai account based ledger. They are not deployable on the UTXO based Qi ledger.

Usage

In practice, the contract utilities are used to connect, read, and call state changing functions on the Quai Ledger. The contract class can be used to interact with any type of contract (Solidity or SolidityX) on any zone chain in the network.

Connect to a Contract

In order to interact with a contract in any read-only capacity, you must “connect” to it using a Provider. You’ll also need to pass the contract’s deployed address and the contract’s ABI.

// set up a remote node provider
const provider = new quais.JsonRpcProvider('https://rpc.sandbox.quai.network')

// connect to the contract using the provider
const contract = new quais.Contract(contractAddress, contractABI, provider)

Call Read Methods

Connecting a simple remote node provider to your contract will allow you to read-only methods.

// get the contract's symbol
const symbol = await contract.symbol()

// get the contract's name
const name = await contract.name()

Call State Changing Methods

If you want to execute a contract state-changing operation, you’ll need to pass a Signer to the contract.

// get signer from pelagus provider
const provider = new quais.JsonRpcProvider(window.pelagus)
const signer = provider.getSigner()

// connect the signer to the contract
const contract = new quais.Contract(contractAddress, contractABI, signer)

// call a state changing contract function
const result = await contract.transferTo('1.0', '0x1234567890123456789012345678901234567890')