How to call function from SmartContract?

Question

I have a smart contract deployed having the following function.

function getTime() public view returns (uint){
       return now;
   }

However, when I try to call the function like this. ("einstance" being the instance of the contract):

tme=einstance.functions.getTime()
tme

I receive:

<Function getTime() bound to ()>

How can I retrieve the time from this?

Answer 1

Try tme=einstance.call().getTime().

Answer 2

It depends on how you have deployed your contract. If it was deployed correctly then you can call.

einstance.functions.getTime().call()

where einstance must be instance of web3._utils.datatypes.Contract.

Little brief on how to install your contract

Step1: Compile your contract and get the bytecode and abi. You can install a specific version of sold compiler on your machine .

For abi
solc --abi test.sol

for bytecode
solc --bin test.sol

The instantiate by copying your abi and bytecode

Test = w3.eth.contract(abi=abi, bytecode=bytecode)

Then you have to deploy your contract, I did it on localchain

w3 = Web3("http://localhost:8545")
w3.eth.defaultAccount = w3.eth.accounts[0]  
tx_hash = Test.constructor().transact()
tx_receipt = w3.eth.waitForTransactionReceipt(tx_hash)

Your deployed contract

deployed = w3.eth.contract(
            address=tx_receipt.contractAddress,
            abi=abi

Now you can call the functions on your deployed contract by

deployed.functions.getTime().call()
>>>1585998887

I used this contract

pragma solidity 0.6.4;

contract Test {

    function getTime() public view returns (uint){
       return now;
   }

}

Make sure your solc compiler (Installed on your machine) is same as in pragma statement.

Answer 3

// Web3 v1.2.6

const Web3 = require('web3');
const web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545'));

const contractJSON = require('/path/to/build/contracts/Contract.json');
const contractInstance = new web3.eth.Contract(contractJSON.abi, 'CONTRACT_DEPLOYED_ADDRESS');

async function getTimeFromContract() {
  const time = await contractInstance.methods.getTime().call();
  console.log(`Time returned from the contract: ${time}`);
}