alchemyplatform / polygon-smart-contract-tutorial

A guide for coding and deploying a basic Polygon (MATIC) smart contract!

How to Code, Deploy, and Interact with a Polygon (MATIC) Smart Contract

Follow the full written tutorial here.

Follow the full video tutorial here.

Quickstart

1. npm install
2. Rename .env-example to .env, and populate the variable values.
   1. Grab API_URL from www.alchemy.com by setting up a Polygon Mumbai testnet app.
   2. For PRIVATE_KEY, use your Ethereum wallet address's corresponding private key.
   3. You can leave CONTRACT_ADDRESS blank until you deploy with npx run scripts/sample-script.js, then grab the address where you deployed your contract to.
   4. ALCHEMY_API_KEY is very similar to API_URL except you can remove the http or ws prefix.
   5. MATIC_URL you can grab from www.alchemy.com but make sure your Alchemy app is a Polygon Mainnet app.
3. run npx run scripts/sample-script.js --network mumbai to deploy your contract to Mumbai testnet
4. run npx run scripts/greet.js --network mumbai to modify blockchain state by calling the Greet function on your smart contract.
5. Repeat those steps with --network matic to deploy and interact on Polygon (MATIC) mainnet chain.

polygon-smart-contract-tutorial's Issues

Failed on matic mainnet with "error: Error: transaction underpriced"

Hi,
thanks for the great tutorial! I tried it on polygon mainnet directly (instead of testnet).
Deploying the contract worked like a charm, I see my contract on the blockchain.

However, setting a new greeting with

npx hardhat run scripts/greet.js

always fails with "error: Error: transaction underpriced". How do I set the gasPrice in

const setTx1 = await Greeter.setGreeting("web3 is ngmi!")

Maybe related, I saw in artifacts/contracts/Greeter.sol/Greeter.json that the function setGreeting appears to be "nonpayable", but shouldn't it be actually be a payble (state-changing) function?

{
      "inputs": [
        {
          "internalType": "string",
          "name": "_greeting",
          "type": "string"
        }
      ],
      "name": "setGreeting",
      "outputs": [],
      "stateMutability": "nonpayable",
      "type": "function"
    }

Retrieve the greeting in scripts/greet.js with console.log("before: " + await Greeter.greet()); does work without problems.

Can you please help me?

Thanks a lot!!!