Interact
Interact with public contracts
This tutorial uses the SimpleStorage.sol
contract:
Copy
pragma solidity ^0.7.0;
contract SimpleStorage {
uint public storedData;
constructor(uint initVal) public {
storedData = initVal;
}
function set(uint x) public {
storedData = x;
}
function get() view public returns (uint retVal) {
return storedData;
}
}
Once the contract is deployed, you can perform a read operation using the get
function call and a write operation using the set
function call. This tutorial uses the web3js library to interact with the contract. The Quorum Developer Quickstart provides a full example of a public contract script.
1. Perform a read operation
To perform a read operation, you need the address that the contract was deployed to and the contract's ABI. The contract's ABI can be obtained from compiling the contract; see the deploying smart contracts tutorial for an example.
Use the web3.eth.Contract
object to create a new instance of the smart contract, then make the get
function call from the contract's list of methods, which will return the value stored:
Copy
async function getValueAtAddress(
host,
deployedContractAbi,
deployedContractAddress,
) {
const web3 = new Web3(host);
const contractInstance = new web3.eth.Contract(
deployedContractAbi,
deployedContractAddress,
);
const res = await contractInstance.methods.get().call();
console.log("Obtained value at deployed contract is: " + res);
return res;
}
2. Perform a write operation
To perform a write operation, send a transaction to update the stored value. As with the get
call, you need to use the address that the contract was deployed to and the contract's ABI. The account address must correspond to an actual account with some ACCES in it to perform the transaction.
Make the set
call passing in your account address, value
as the updated value of the contract, and the amount of gas you are willing to spend for the transaction:
Copy
// You need to use the accountAddress details provided to GoQuorum to send/interact with contracts
async function setValueAtAddress(
host,
accountAddress,
value,
deployedContractAbi,
deployedContractAddress,
) {
const web3 = new Web3(host);
const contractInstance = new web3.eth.Contract(
deployedContractAbi,
deployedContractAddress,
);
const res = await contractInstance.methods
.set(value)
.send({ from: accountAddress, gasPrice: "0x0", gasLimit: "0x24A22" });
return res;
}
3. Verify an updated value
To verify that a value has been updated, perform a get
call after a set
update call.
Last updated
Was this helpful?