Hi @MWaser
Yes.
You may want to look at the Interacting Programmatically guide and using OpenZeppelin Contract Loader.
Yes.
Though as far as I am aware events don't impact contract storage (for upgradeable contracts). I will confirm on this topic: Using events in upgradeable contracts?
I assume so too.
To try this out, I created a project for the Box contract
Box.sol
// contracts/Box.sol
pragma solidity ^0.5.0;
contract Box {
uint256 private value;
// Emitted when the stored value changes
event ValueChanged(uint256 newValue);
// Stores a new value in the contract
function store(uint256 newValue) public {
value = newValue;
emit ValueChanged(newValue);
}
// Reads the last stored value
function retrieve() public view returns (uint256) {
return value;
}
}
Deploy
Using OpenZeppelin CLI 2.8 Release Candidate deploying to ganache-cli
$ npx oz deploy
✓ Compiled contracts with solc 0.5.16 (commit.9c3226ce)
? Choose the kind of deployment upgradeable
? Pick a network development
? Pick a contract to deploy Box
✓ Added contract Box
✓ Contract Box deployed
All implementations have been deployed
? Call a function to initialize the instance after creating it? No
✓ Setting everything up to create contract instances
✓ Instance created at 0xCfEB869F69431e42cdB54A4F4f105C19C080A601
0xCfEB869F69431e42cdB54A4F4f105C19C080A601
Interact
$ npx oz send-tx
? Pick a network development
? Pick an instance Box at 0xCfEB869F69431e42cdB54A4F4f105C19C080A601
? Select which function store(newValue: uint256)
? newValue: uint256: 42
✓ Transaction successful. Transaction hash: 0x9f007d7f0fcb278a979fafecfceb45a9190b707bb8a0c08a90ce33a16e5feaff
Events emitted:
- ValueChanged(42)
In a separate project (based on Interacting Programmatically guide)
Install web3 and OpenZeppelin Contract-Loader
$ npm install web3 @openzeppelin/contract-loader
JavaScript to get past events
// src/index.js
const Web3 = require('web3');
const { setupLoader } = require('@openzeppelin/contract-loader');
async function main() {
// Set up web3 object, connected to the local development network, and a contract loader
const web3 = new Web3('http://localhost:8545');
const loader = setupLoader({ provider: web3 }).web3;
// Set up a web3 contract, representing our deployed Box instance, using the contract loader
const address = '0xCfEB869F69431e42cdB54A4F4f105C19C080A601';
const box = loader.fromArtifact('Box', address);
box.getPastEvents('ValueChanged', {
fromBlock: 0,
toBlock: 'latest'
}, function(error, events){ console.log(events); });
}
main();
Copy build/contracts from other project
Run script
$ node ./src/index.js
[ { logIndex: 0,
transactionIndex: 0,
transactionHash:
'0x9f007d7f0fcb278a979fafecfceb45a9190b707bb8a0c08a90ce33a16e5feaff',
blockHash:
'0xa4e5a458f7e8f88016f90455beb4daa4e47b4618d16b7de648e536a3be64e383',
blockNumber: 4,
address: '0xCfEB869F69431e42cdB54A4F4f105C19C080A601',
type: 'mined',
id: 'log_bc7583d8',
returnValues: Result { '0': '42', newValue: '42' },
event: 'ValueChanged',
signature:
'0x93fe6d397c74fdf1402a8b72e47b68512f0510d7b98a4bc4cbdf6ac7108b3c59',
raw:
{ data:
'0x000000000000000000000000000000000000000000000000000000000000002a',
topics: [Array] } } ]
Box.sol (updated)
Add an additional event
// contracts/Box.sol
pragma solidity ^0.5.0;
contract Box {
uint256 private value;
// Emitted when the stored value changes
event ValueChanged(uint256 newValue);
event ValueChanging(uint256 oldValue, uint256 newValue);
// Stores a new value in the contract
function store(uint256 newValue) public {
emit ValueChanging (value, newValue);
value = newValue;
emit ValueChanged(newValue);
}
// Reads the last stored value
function retrieve() public view returns (uint256) {
return value;
}
}
Upgrade
$ npx oz upgrade
? Pick a network development
✓ Compiled contracts with solc 0.5.16 (commit.9c3226ce)
✓ Contract Box deployed
All implementations have been deployed
? Which instances would you like to upgrade? Choose by address
? Pick an instance to upgrade Box at 0xCfEB869F69431e42cdB54A4F4f105C19C080A601
? Call a function on the instance after upgrading it? No
✓ Instance upgraded at 0xCfEB869F69431e42cdB54A4F4f105C19C080A601. Transaction receipt: 0xcd85e8481c8e15f37a2822e5ac829cec315484dc8cddde37625270358ff9370f
✓ Instance at 0xCfEB869F69431e42cdB54A4F4f105C19C080A601 upgraded
Interact
$ npx oz send-tx
? Pick a network development
? Pick an instance Box at 0xCfEB869F69431e42cdB54A4F4f105C19C080A601
? Select which function store(newValue: uint256)
? newValue: uint256: 23
✓ Transaction successful. Transaction hash: 0x3e607e53c9ff6d8831673840d6edc99e44cb7d75b52f469a7704300c7097d028
Events emitted:
- ValueChanging(42, 23)
- ValueChanged(23)
Run script
Without updating artifacts in project, run script
$ node ./src/index.js
[ { logIndex: 0,
transactionIndex: 0,
transactionHash:
'0x9f007d7f0fcb278a979fafecfceb45a9190b707bb8a0c08a90ce33a16e5feaff',
blockHash:
'0xa4e5a458f7e8f88016f90455beb4daa4e47b4618d16b7de648e536a3be64e383',
blockNumber: 4,
address: '0xCfEB869F69431e42cdB54A4F4f105C19C080A601',
type: 'mined',
id: 'log_bc7583d8',
returnValues: Result { '0': '42', newValue: '42' },
event: 'ValueChanged',
signature:
'0x93fe6d397c74fdf1402a8b72e47b68512f0510d7b98a4bc4cbdf6ac7108b3c59',
raw:
{ data:
'0x000000000000000000000000000000000000000000000000000000000000002a',
topics: [Array] } },
{ logIndex: 1,
transactionIndex: 0,
transactionHash:
'0x3e607e53c9ff6d8831673840d6edc99e44cb7d75b52f469a7704300c7097d028',
blockHash:
'0x65c9aa204213922c0db2afe8c45625eb5905b06a2332bfd20576a677eca5dac0',
blockNumber: 7,
address: '0xCfEB869F69431e42cdB54A4F4f105C19C080A601',
type: 'mined',
id: 'log_8120791b',
returnValues: Result { '0': '23', newValue: '23' },
event: 'ValueChanged',
signature:
'0x93fe6d397c74fdf1402a8b72e47b68512f0510d7b98a4bc4cbdf6ac7108b3c59',
raw:
{ data:
'0x0000000000000000000000000000000000000000000000000000000000000017',
topics: [Array] } } ]
Change script to get events for ValueChanging event and get an error
$ node ./src/index.js
(node:14909) UnhandledPromiseRejectionWarning: Error: Event "ValueChanging" doesn't exist in this contract.
Copy artifacts and rerun
$ node ./src/index.js
[ { logIndex: 0,
transactionIndex: 0,
transactionHash:
'0x3e607e53c9ff6d8831673840d6edc99e44cb7d75b52f469a7704300c7097d028',
blockHash:
'0x9dec8e13054fba7872c5e56bd5ed354dfb97c798f1a8151682b06dced9156011',
blockNumber: 7,
address: '0xCfEB869F69431e42cdB54A4F4f105C19C080A601',
type: 'mined',
id: 'log_a08093e6',
returnValues:
Result { '0': '42', '1': '23', oldValue: '42', newValue: '23' },
event: 'ValueChanging',
signature:
'0x737c5296e2c8ee4fe448f01f4b31dc800ecc70702e1f71a3d02d02eb441d5fb2',
raw:
{ data:
'0x000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000017',
topics: [Array] } } ]
)