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I have created a smart contract in which a "stop()" function should be called once a deadline is reached. Dapp is keeping check of the deadline and as soon as the deadline is reached I need to call this function, the function itself actually sends some amount of ethers to 3 different addresses.

Here is the stop function:

function stop() public{
    require(now > deadline, "deadline expired");
    require(address(this).balance >= 1 ether, "contract doesnot have sufficient ethers");
   // quickSort(top, 0, top.length-1);
   for(uint i = 0; i < registeredStudents; i++)
        sort(i);
    // distribute the tokens
    for(uint i = 0; i <= 2; i++){
        students[top[i]].wallet.transfer((3-i) * 100000000000000000);
        emit Transferred(students[top[i]].wallet, top[i], 3-i);
        students[top[i]].totalBalance += (3-i) * 100000000000000000;
    }
}

How can I call this function from the Dapp? I tried using call() but it is not working and I tried send() too but send() wants me to give from address as well, which I dont know should be what in this case.

Please suggest. It is urgent task. Thanks in advance.

2

Yes you need to use send. Here is the code:

    const result = await contract.methods.stop()
          .send( { gas: '1500000', gasPrice: `30000000000000`, from:accounts[0]});

This code needs to be placed in an async function as it uses the async/await pattern!

Regarding your question with the from address. This is a state changing transaction. Therefore, it needs to be mined and costs gas!!

You need to access one of you accounts. Initialize web3 with your provider.

const web3 = new Web3(provider);

Now get the accounts.

const accounts = await web3.eth.getAccounts();

This array now gets passed into the send function you see above.

EDIT: Adjust value of gas and gasPrice to fit your needs.

  • thanks, I know this way but isn't there any automatic way to do this? because in reality I want the dapp to do itself instead of asking user to confirm the transaction. – Fariha Abbasi Nov 25 '19 at 19:15
  • I don't know how your dapp exactly works, but it seems like you need to call this function a lot of times. There is the option that you pay for the tx cost (as the transaction SURELY costs gas). – Niklas Feurstein Nov 25 '19 at 20:57

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