Resources

[vivi365]

Basics 😎

• Deploying locally in hardhat and interacting through the console - Openzeppelin
• Tests with chai - Openzeppelin
• Connecting to a test network - Openzeppelin

[vivi365]

How to interact with a contract deployed locally in hardhat

• Deploying locally in hardhat and interacting through the console - Openzeppelin

Set up

1. Start the network with npx hardhat node
2. Create a deployment script
3. run deployment script with localhost network: npx hardhat run --network localhost scripts/deploy.js
4. Get contract address from deployment on localhost
5. Open the hardhat console in localhost: npx hardhat console --network localhost
6. Interact!

How to interact:

We are using the ethers api

1. const Company = await ethers.getContractFactory('CONTRACT NAME')
2. const company = Company.attach('HEXADDRESS HERE');
3. Use any contract addresses using async await to avoid promises. save data in e.g. a var.- var greeting = await company.register("hello");
4. Use toString when displaying unit256 which is too big for java... eg company.retrieve()).toString()

Namespaces in ethers API

• Providers - like an ethereum node
• Signers - ethereum accounts/wallets..
• Contract interaction

[vivi365]

Calling a contract from another contract

Example

import "./access-control/Auth.sol";
contract Hello {
  Auth private _auth;
  constructor() {
        _auth = new Auth(msg.sender);
    }
  function hi() {
    require(_auth.isAdministrator(msg.sender), "Unauthorized");}
}