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Hardhat Smartcontract Lottery (Raffle) FCC
This repo has been updated to work with Sepolia over Goerli.
This is a section of the Javascript Blockchain/Smart Contract FreeCodeCamp Course.
⌨️ (13:41:02) Lesson 9: Hardhat Smart Contract Lottery
- Hardhat Smartcontract Lottery (Raffle) FCC
- Getting Started
- Usage
- Deployment to a testnet or mainnet
- Linting
- Thank you!
This project is apart of the Hardhat FreeCodeCamp video.
Checkout the full blockchain course video here.
Getting Started
Requirements
- git
- You'll know you did it right if you can run
git --version
and you see a response likegit version x.x.x
- You'll know you did it right if you can run
- Nodejs
- You'll know you've installed nodejs right if you can run:
node --version
and get an output like:vx.x.x
- It'll need to be at least
18.16.0
of node
- You'll know you've installed nodejs right if you can run:
- Yarn instead of
npm
- You'll know you've installed yarn right if you can run:
yarn --version
and get an output like:x.x.x
- You might need to install it with
npm
orcorepack
- You'll know you've installed yarn right if you can run:
Quickstart
git clone https://github.com/PatrickAlphaC/hardhat-smartcontract-lottery-fcc
cd hardhat-smartcontract-lottery-fcc
yarn
Typescript
If you want to get to typescript and you cloned the javascript version, just run:
git checkout typescript
yarn
Usage
Deploy:
yarn hardhat deploy
Testing
yarn hardhat test
Test Coverage
yarn hardhat coverage
Deployment to a testnet or mainnet
- Setup environment variables
You'll want to set your SEPOLIA_RPC_URL
and PRIVATE_KEY
as environment variables. You can add them to a .env
file, similar to what you see in .env.example
.
PRIVATE_KEY
: The private key of your account (like from metamask). NOTE: FOR DEVELOPMENT, PLEASE USE A KEY THAT DOESN'T HAVE ANY REAL FUNDS ASSOCIATED WITH IT.- You can learn how to export it here.
SEPOLIA_RPC_URL
: This is url of the sepolia testnet node you're working with. You can get setup with one for free from Alchemy
- Get testnet ETH
Head over to faucets.chain.link and get some testnet ETH & LINK. You should see the ETH and LINK show up in your metamask. You can read more on setting up your wallet with LINK.
- Setup a Chainlink VRF Subscription ID
Head over to vrf.chain.link and setup a new subscription, and get a subscriptionId. You can reuse an old subscription if you already have one.
You can follow the instructions if you get lost. You should leave this step with:
-
A subscription ID
-
Your subscription should be funded with LINK
-
Deploy
In your helper-hardhat-config.js
add your subscriptionId
under the section of the chainId you're using (aka, if you're deploying to sepolia, add your subscriptionId
in the subscriptionId
field under the 11155111
section.)
Then run:
yarn hardhat deploy --network sepolia
And copy / remember the contract address.
- Add your contract address as a Chainlink VRF Consumer
Go back to vrf.chain.link and under your subscription add Add consumer
and add your contract address. You should also fund the contract with a minimum of 1 LINK.
- Register a Chainlink Keepers Upkeep
You can follow the documentation if you get lost.
Go to keepers.chain.link and register a new upkeep. Choose Custom logic
as your trigger mechanism for automation. Your UI will look something like this once completed:
- Enter your raffle!
Your contract is now setup to be a tamper proof autonomous verifiably random lottery. Enter the lottery by running:
yarn hardhat run scripts/enter.js --network sepolia
Estimate gas cost in USD
To get a USD estimation of gas cost, you'll need a COINMARKETCAP_API_KEY
environment variable. You can get one for free from CoinMarketCap.
Then, uncomment the line coinmarketcap: COINMARKETCAP_API_KEY,
in hardhat.config.js
to get the USD estimation. Just note, everytime you run your tests it will use an API call, so it might make sense to have using coinmarketcap disabled until you need it. You can disable it by just commenting the line back out.
Verify on etherscan
If you deploy to a testnet or mainnet, you can verify it if you get an API Key from Etherscan and set it as an environment variable named ETHERSCAN_API_KEY
. You can pop it into your .env
file as seen in the .env.example
.
In its current state, if you have your api key set, it will auto verify sepolia contracts!
However, you can manual verify with:
yarn hardhat verify --constructor-args arguments.js DEPLOYED_CONTRACT_ADDRESS
Typescript differences
.js
files are now.ts
- We added a bunch of typescript and typing packages to our
package.json
. They can be installed with:yarn add @typechain/ethers-v5 @typechain/hardhat @types/chai @types/node ts-node typechain typescript
- The biggest one being typechain
- This gives your contracts static typing, meaning you'll always know exactly what functions a contract can call.
- This gives us
factories
that are specific to the contracts they are factories of. See the tests folder for a version of how this is implemented.
- We use
imports
instead ofrequire
. Confusing to you? Watch this video - Add
tsconfig.json
Linting
To check linting / code formatting:
yarn lint
or, to fix:
yarn lint:fix
Thank you!
If you appreciated this, feel free to follow me or donate!
ETH/Polygon/Avalanche/etc Address: 0x9680201d9c93d65a3603d2088d125e955c73BD65