Dutch Auction Dapp

This Dutch Auction Dapp is built with Hardhat.

Project Layout

There are three top-level folders:

1. ./app - contains the front-end application
2. ./contracts - contains the solidity contract
3. ./nfts - contains nft assets and metadata
4. ./tasks - contains hardhat tasks
5. ./tests - contains tests for the solidity contract

Setup

Install dependencies in the top-level directory with npm install.

After you have installed hardhat locally, you can use commands to test and compile the contracts, among other things. To learn more about these commands run npx hardhat help.

Compile the contracts using npx hardhat compile. The artifacts will be placed in the /app folder, which will make it available to the front-end. This path configuration can be found in the hardhat.config.js file.

Environment

Setup a local .env file, which can be based on the file ./.env.example.

Upload NFT data to Pinata or similar service.

1. If you don't already have an account on Pinata, setup a free account there now.
2. Once you have an account, upload the file ./nfts/tulip.jpg to Pinata.
3. After you've uploaded the file, click on the file on the Pinata website. Then copy down the Pinata CID of the uploaded file. The CID is the last part of the Pinanta URL. ie: https://gateway.pinata.cloud/ipfs/CID
4. Copy the file ./nfts/tulip-metadata.json.example to ./nfts/tulip-metadata.json.
5. Open the file ./nfts/tulip-metadata.json and change <CID> of the variable image to be the Pinata CID that you copied in step 3. Now upload the file ./nfts/tulip-metadata.json to Pinata as well. Once the file has been uploaded, click on the file on Pinata website.
6. Copy the Pinata URL of the tulip-metadata.json you just uploaded and paste the value into your ./env file as the value of the NFT_TOKEN_METADATA_URI variable.

Run the tests

From the root dir of the project run:

npx hardhat test --config hardhat.test.config.js

and check that all the tests are passing.

Notice that here we specify a specific Hardhat config file via --config hardhat.test.config.js. The reason for this is that in the main hardhat.config.js we configure Hardhat to do 'interval mining' (ie: automatically mine blocks every given interval). We need this to simulate the behavior of a real blockchain, which produces blocks with time. However, this is bad for tests as we want them to run quickly. Hardhat's default mining strategy is 'auto mining' which means every time a transaction is sent to the blockchain (not just a query, but a state-changing transaction), which is the mining strategy we want to use for fast tests. You can read more about Hardhat's mining strategy in Hardhat's Mining Modes documentation section.

Deploying contracts and minting NFTs

This project makes use of custom Hardhat Tasks to do a lot of the command-line administrative work of deploying contracts and minting NFTs. You can find these tasks in ./tasks/nft.js and ./tasks/dutch-auction.js respectively.

You can also learn more about the tasks by running:

npx hardhat --help

to get a list of all the Hardhat tasks.

To get even more specific information about a task you can run:

npx hardhat <task_name> --help

Hardhat Tasks provide a lot of convenience because they add a lot of CLI functionality, like parsing required CLI arguments and options and validating that the arguments are of the correct type. When a given Hardhat task runs it has all the expected CLI args that the task defines as well as access to the HardhatRuntimeEnvironment variable.

You can learn a lot more about Hardhat Tasks in the HardHat Documentation and by looking at the example tasks in this project in the ./tasks dir.

For the purposes of getting this project up and running you only need to run the deploy-all task defined in the ./tasks/dutch-auction.js file.

The deploy-all task does 3 things:

1. deploy the NFT Tulip.sol contract
2. deploy the DutchAuction.sol contract
3. mint a new Tulip NFT.

To run deploy-all, first start a local Hardhat node in a terminal window:

npx hardhat node

This local node is accessible at http://localhost:8545 and uses chain id 31337 by default. Once the local node is running, you are ready to deploy your contracts and mint your new NFT via:

npx hardhat deploy-all --network localhost --token-uri <YOUR_TOKEN_URI>

where YOUR_TOKEN_URI is the value you saved in the NFT_TOKEN_METADATA_URI variable of your .env file. Note: specifying --network localhost here is very important if you want your contracts to be deployed to the running Hardhat node you just started. Without --network localhost, your contracts will be deployed to a temporal Hardhat note that will disappear as soon as the deployment finishes.

Upon successful deployment of everything you should see a message in your console similar to this:

Dutch Auction for NFT '<NFT_CONTRACT_ADDR>' contract deployed to address: <DUTCH_AUCTION_CONTRACT_ADDR>

Take the <DUTCH_AUCTION_CONTRACT_ADDR> value from the console and paste it into your .env file as the value of the DUTCH_AUCTION_CONTRACT_ADDR variable.

Front-End

Finally, you're ready to fire up the front-end and see what all this looks like in the browser. To run the front-end application cd into the app folder and run npx parcel index.html.

You can learn more about Parcel here.

⚠️ Notes

Beware of Metamask nonce issues. Note that when the Hardhat Task deploy-all runs, it creates 3 transactions as described in the Deploying contracts and minting NFTs above. This means that nonces 0, 1 and 2 have already been used. When you first load the front-end Dapp and connect to it using Metamask and the Hardhat 0 signer, you will see a button to approve the NFT Token for listing by the Dutch Auction contract. When you click the button to do the approval, you will need to manually override Metamask's nonce to be 3, since 3 transactions will have already been done in the deploy-all step.