Evrlink Backend

Overview

Evrlink is a backend application for managing an NFT gift marketplace. It enables users to mint NFT backgrounds, create and transfer gift cards, and handle transactions. The backend is built with Node.js, Express, and PostgreSQL, and integrates with Ethereum smart contracts (Solidity). The project leverages a variety of tools for development, deployment, and testing.

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Tools & Technologies

• Node.js: JavaScript runtime for backend logic.
• Express: Web framework for RESTful APIs.
• MySQL: Relational database for persistent storage.
• Sequelize: ORM for database interaction.
• dotenv: Environment variable management.
• Ethereum (Solidity): Smart contracts for NFT and gift card logic.
• Hardhat: Ethereum development environment for compiling, deploying, and testing smart contracts.
• Ethers.js: Ethereum wallet and contract interaction.
• Chai: Testing framework for backend and smart contracts.
• CORS: Security and logging middleware.
• Frontend Integration: Serves a frontend build.

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Functionality

• User Management: Register, authenticate, and manage users.
• NFT Backgrounds: Mint, list, and manage NFT backgrounds.
• Gift Cards: Create, transfer, and redeem NFT-based gift cards.
• Transactions: Record and retrieve transaction history.
• Wallet Integration: Connect and interact with Ethereum wallets.
• Smart Contract Interaction: Mint NFTs, transfer ownership, and verify transactions on-chain.
• API Endpoints: RESTful endpoints for all major resources.
• Frontend Serving: Optionally serves a frontend SPA if configured.
• Testing: Comprehensive backend and smart contract tests.
• Database Migration & Seeding: Scripts for initializing and populating the database.

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Project Structure

evrlink-backend-base-batch
├── contracts
│   ├── GiftCard.sol
│   ├── MockUSDC.sol
├── dist/
│   └── services/
│       └── onchain-agent/
│           ├── create-agent.js
│           └── prepare-agentkit.js
├── evrlink_chatbot/
├── scripts
│   ├── deploy.js
│   ├── deployMockUSDC.js
│   ├── mintMockUSDC.js
│   ├── uploadToS3.js
│   └── usdc_deploy.js
├── services
│   ├── agent.service.js
│   ├── blockchain.js
│   ├── onchain-agent/
│   │   ├── create-agent.js / .ts
│   │   └── prepare-agentkit.js / .ts
│   └── utils/
│       ├── blockchain-updates.js
│       └── crypto.js
├── src
│   ├── app.js
│   ├── server.js
│   ├── contracts/
│   │   └── GiftCard.json
│   ├── controllers/
│   │   └── dbController.js
│   ├── middleware/
│   │   ├── auth.js
│   │   └── multer.js
│   ├── models/
│   │   ├── ArtNft.js
│   │   ├── Background.js
│   │   ├── BlockchainTransaction.js
│   │   ├── BlockchainTransactionCategory.js
│   │   ├── BlockchainTransactionGiftcard.js
│   │   ├── EvrlinkConstant.js
│   │   ├── GiftCard.js
│   │   ├── GiftCardArtNft.js
│   │   ├── GiftCardCategory.js
│   │   ├── GiftCardSecret.js
│   │   ├── GiftCardSettlement.js
│   │   ├── Transaction.js
│   │   ├── User.js
│   │   ├── UserRole.js
│   │   └── index.js
│   ├── routes/
│   │   ├── agent.routes.js
│   │   ├── auth.routes.js
│   │   ├── background.routes.js
│   │   ├── backgrounds.js
│   │   ├── chatbot.routes.js
│   │   ├── giftCard.routes.js
│   │   ├── image.routes.js
│   │   ├── index.js
│   │   ├── nft.routes.js
│   │   ├── user.routes.js
│   │   └── wallet.routes.js
├── test/
│   ├── Giftcard.test.js
│   └── NFTGiftMarketplace.test.js
├── .env
├── buildspec.yml
├── config.js
├── package.json
├── README.md
└── server.js

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Getting Started

1. Clone the Repository

git clone <repository-url>
cd evrlink2-backend

2. Install Dependencies

Installs all Node.js dependencies (backend, smart contract, and tooling):

npm install

3. Configure Environment Variables

Create a .env file in the root directory with the following:

5. Smart Contract Development & Deployment

• Contracts are in the contracts/ directory (e.g., GiftCard.sol).
• Use Hardhat for compiling, deploying, and testing contracts.

Compile contracts:

npm run compile

Deploy to Base Sepolia:

1. Ensure your .env is set up with the correct RPC URL and private key.
2. Run your deployment script:

   npx hardhat run scripts/deploy.js --network base_sepolia

3. Update the deployed contract address in your .env file.

Verify contract (optional):

npx hardhat verify --network base_sepolia <DEPLOYED_CONTRACT_ADDRESS>

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Running the Application

Development Mode

Runs the backend with auto-reload on changes (if nodemon is installed):

npm run dev

Production Mode

Runs the backend server (ensure all environment variables are set):

npm start

Or, using PM2 for process management:

pm2 start src/app.js --name evrlink2-backend

What Runs

• Backend API: RESTful endpoints for all resources.
• Smart Contract Integration: All NFT and gift card operations interact with the deployed smart contract.
• Database: All persistent data is stored in MySQL.
• Frontend Serving: If FRONTEND_DIST_PATH is set, the backend serves the frontend SPA.
• Logging & Security: Middleware for logging requests and securing HTTP headers.
• Testing: Run backend and smart contract tests as described below.

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Testing

Backend tests:
Runs all backend unit/integration tests (see test/):

npm test

Smart contract tests:
Runs all smart contract tests using Hardhat:

npx hardhat test

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Deployment

• Ensure all environment variables are set for production.
• Secure your .env file and never commit secrets to version control.

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Contributing

Contributions are welcome! Please open issues or submit pull requests for improvements or bug fixes.

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Contact

For questions or onboarding, please reach out to the project maintainer or check the internal documentation.