Metamask: How to access/call deployed contract's functions using Metamask

Question

I'm learning Solidity. I've set up Metamask, truffle and testrpc. I can send ether from one account to another via metamask. But I want to Metamask to access my deployed contract, and call my contract functions.

Question: Can I test and interact with my deployed contract using metamask?

Answer 1

Not using Metamask alone, but you can in combination with other tools. One such tool is MyEtherWallet; go to the "Contracts" tab, enter the contract address and ABI, click Access, and then choose "Metamask/Mist" as the means you want to access your wallet. Then MyEtherWallet will give you the UI to construct the transaction, and when it's time to broadcast it, it will give you a Metamask popup to sign and transmit it.

Answer 2

Metamask is great for client side interactions with smart contracts and their functions. If installed, you can access the web3 that is injected into your browser:

// Get the contract instance using your contract's abi and address:
const contractInstance = web3.eth.contract(abi).at(contractAddress);

// Call a function of the contract:
contractInstance.someFunction({ from: sender, value: someValue, gas: limit },
  (err, res) => { /** do something with results **/ });

You can even access the currently selected account in metamask with web3.eth.accounts[0].

This will require some front end development, but it's pretty straight forward.

The other alternative is to use Ethereum Wallet > Contracts > Watch Contract. Again, enter the contract address and abi, and you can access all of the contract's functions through Ethereum Wallet's UI.

Answer 3

Example:

web3 = new Web3(web3.currentProvider);
  let myContract = new web3.eth.Contract(abi, address);
  let amount = 1;
  amount = web3.utils.toWei(amount.toString(), 'ether');
  let response = await myContract.methods
    .createPayment(1, address)  //function in contract
    .send({
      from: window.web3.currentProvider.selectedAddress,
      to: address,
      value: amount,
      gasPrice: '20000000000' 
    });
  console.log("response: ", response);

Answer 4

MyEtherWallet and Mist wallet both are deprecated now.
One of the best alternatives to these is MyCrypto wallet. It is recommended by the MEW and mist developers also. It has simplistic web UI as well as desktop versions are also available.

Answer 5

This works in 2022, change the abi and address , and put it in your HTML file:

    async function loadWeb3() {
      if (window.ethereum) {
        window.web3 = new Web3(window.ethereum);
        window.ethereum.enable();
      }
    }

    async function loadContract() {
      let abi = [] // your abi here
      let address = "0xa1b2c3d4..."  // your contract address here
      return await new window.web3.eth.Contract(abi, address);
    }
    async function getCurrentAccount() {
      const accounts = await ethereum.request({ method: 'eth_requestAccounts' });
      return accounts[0];
    }

    async function run() {
      await loadWeb3();
      window.contract = await loadContract();
      const account = await getCurrentAccount();
      let result = await window.contract.methods.mint().send({ from: account });
    }

    if (typeof window.ethereum !== 'undefined') {
      run()
    }

refer to: https://ethereum.stackexchange.com/a/131437/30431