Celo 101 - Marketplace

1. Introduce

This project implements a simple marketplace to manage / selling product. It's based on great course of Celo in the Dacade. It helps us to understand about Solidity, Celo blockchain, and how to make a fullstack application base on them.

The feature includes:

• See products hosted on the Celo Blockchain
• Purchase products with cUSD and pay the owner
• Add your own products to the dApp
• Record purchase history

On-going implementation (by order)

• Pagination
• Searching
• Only verified merchant can add product
• Merchant can check income / revenue in total or by product
• Voting or commenting in purchased product (only customer who purchase can vote)
• Category (labeling product type)
• Tracking order

Demo website: https://marketplace-andyle83.vercel.app/

2. Technology Stack

Blockchain

• Written in Solidity for Celo blockchain network
• Deploying in Celo testnet: https://alfajores-blockscout.celo-testnet.org/
• Deploy address: 0x052F92eF1B97c0dD68B7150a8BBeBf962dD8a4e7 (can be changed)
• Development framework: HardHat & Laika

Backend [TBD]

• Using ORM (i.e, Prisma) and Postgres database to store off-chain data / fall-over solution
• Heroku to host Postgres

Frontend

There are two variants of implementation:

• Node.js application (app folder)

  • Webpack as module bundler
  • Celo ContractKit
  • Using jQuery to update UI component with simple even handler function
  • Bootstrap UI framework

• Next.js framework (react-app folder)

  • Using use-contractkit library
  • Apollo Client for GraphQL queries
  • Bootstrap UI framework

3. Showcase

Marketplace

• Desktop

• Mobile

Wallet Connect

Purchase Product

Create Product

Purchase History

4. Testing

Running Unit Testing Smart Contract

• Local network - Testing using hardhat gauche package:

npm run test

• Local network - Testing using hardhat node:

npx hardhat node
npx hardhat test

• Testing network:

npx hardhat test --network alfajores

Running manual test (using Laika)

• Deploy in testnet:

npx hardhat run scripts/sample-script.js --network alfajores

Output

No need to generate any newer typings.
Marketplace deployed to: 0xB67880E89e79aA1529532677Cc07e2ab007e6443

• Sync:

npx hardhat laika-sync --contract Marketplace --address 0xB67880E89e79aA1529532677Cc07e2ab007e6443

5. TODO

• CI/CD (Applying Vercel)
  • Integration Testing: [TBD]
  • CI/CD Pipeline

vercel
vercel --prod

• New features
  • Voting / Comment from customer
  • Sorting / Pagination / Category
  • Searching
  • Multi-items checkout
  • Buying history
  • Recommendation (or any Personalization)
• Backend
  • Using database to improve performance / or store "big" data like images
  • Extra customer profile (email, phone). It helps customer engagement / personalization
  • Administration features
  • Not everyone can add new product / category (admin, group of admin)
  • Selling reporting etc..

6. Useful commands

Celo-cli

• New account

celocli account:new

• Check configure

celocli config:get

• Set configure (for network)

celocli config:set --node=https://alfajores-forno.celo-testnet.org

• Get balance (sample address)

celocli account:balance 0xbDEA9f367e9a92b41e91525AEC13d3aDFb027a68

Hardhat

• Console (for configuration)

npx hardhat console

• Accounts

npx hardhat accounts

• Clean up

npx hardhat clean

• Compile

npx hardhat compile

• In-memory network

npx hardhat node

• Testing

npx hardhat test
npx hardhat test --network alfajores

• Deploy

npx hardhat run scripts/sample-script.js --network alfajores

Laika (similar as Postman)

• Syn command

npx hardhat laika-sync --contract Marketplace --address 0x052F92eF1B97c0dD68B7150a8BBeBf962dD8a4e7

7. Issues

1. Not able to run in localhost. Solution

   • Start the hardhat node as in-memory local blockchain
   • Update hardhat configure with right address (localhost) and port

2. Trying to insert concurrent (multi products) at the same time in Testnet, and get an issue

   Error: replacement fee too low [ See: https://links.ethers.org/v5-errors-REPLACEMENT_UNDERPRICED 

3. Trying to make unit test for buyProduct but transaction was reverted with error:

   ProviderError: VM Exception while processing transaction: revert

   • Running hardhat in-memory blockchain npx hardhat node
   • Running unit test in hardhat node npx hardhat test --network localhost
   • Checking output in hardhat console log

eth_chainId
eth_getTransactionByHash
eth_chainId
eth_getTransactionReceipt
eth_chainId
eth_estimateGas
  Contract call:       Marketplace#buyProduct
  From:                0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266
  To:                  0x0165878a594ca255338adfa4d48449f69242eb8f
  Value:               0 ETH

  Error: Transaction reverted: function call to a non-contract account
      at Marketplace.buyProduct (contracts/Marketplace.sol:88)
      at async EthModule._estimateGasAction (/Users/Anh.Le/Workspace/GitHub/celo-101/contract/node_modules/hardhat/src/internal/hardhat-network/provider/modules/eth.ts:425:7)
      at async HardhatNetworkProvider._sendWithLogging (/Users/Anh.Le/Workspace/GitHub/celo-101/contract/node_modules/hardhat/src/internal/hardhat-network/provider/provider.ts:139:22)
      at async HardhatNetworkProvider.request (/Users/Anh.Le/Workspace/GitHub/celo-101/contract/node_modules/hardhat/src/internal/hardhat-network/provider/provider.ts:116:18)
      at async JsonRpcHandler._handleRequest (/Users/Anh.Le/Workspace/GitHub/celo-101/contract/node_modules/hardhat/src/internal/hardhat-network/jsonrpc/handler.ts:188:20)
      at async JsonRpcHandler._handleSingleRequest (/Users/Anh.Le/Workspace/GitHub/celo-101/contract/node_modules/hardhat/src/internal/hardhat-network/jsonrpc/handler.ts:167:17)
      at async Server.JsonRpcHandler.handleHttp (/Users/Anh.Le/Workspace/GitHub/celo-101/contract/node_modules/hardhat/src/internal/hardhat-network/jsonrpc/handler.ts:52:21)

Reference

• Celo Development 101
• The Ultimate Guide to Deploy Celo dApps using Hardhat