How to retrieve data from an Ethereum Block?

0 votes

I did one small event registration smart contract in which I purchased a ticket for an event by giving the details of my email id and no.of tickets I want. I am using testrpc, truffle, and private net. After clicking on purchase I got these details in tetrpc terminal

Transaction: 0x35e92857102b0dbacd43234d1ea57790405eb9bef956b245c6b7737bc23d011b
Gas usage: 106532 Block Number: 5 Block Time: Sat Feb 03 2018 12:05:57 GMT+0530 (IST)

Transaction: 0x35e92857102b0dbacd43234d1ea57790405eb9bef956b245c6b7737bc23d011b
Gas usage: 106532 Block Number: 5 Block Time: Sat Feb 03 2018 12:05:57 GMT+0530 (IST)

This is how I decode the transaction Id:

sam123@ubuntu:~/EventRegistration-POC/EventRegistration$ truffle console
truffle(development)> web3.eth.getTransaction('0x35e92857102b0dbacd43234d1ea57790405eb9bef956b245c6b7737bc23d011b')
{ hash: '0x35e92857102b0dbacd43234d1ea57790405eb9bef956b245c6b7737bc23d011b',
  nonce: 4,
  blockHash: '0x7c790dae57babfe40d68d8aad94913c2b748501c5734aec86cc3fcf0afc4f154',
  blockNumber: 5,
  transactionIndex: 0,
  from: '0x031e060414a0d2573f5b10bc75c0894d72288292',
  to: '0xa88a366e888bbccfb78092957ffc7760bc7c6db1',
  value: BigNumber { s: 1, e: 18, c: [ 60000 ] },
  gas: 200000,
  gasPrice: BigNumber { s: 1, e: 0, c: [ 1 ] },
  input: '0xa28f161c00000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000b6d40676d61696c2e636f6d000000000000000000000000000000000000000000' }
truffle(development)> 

But I didn't get the details I was given while purchasing. How to do this?

Jul 19, 2018 in Blockchain by sabby
• 4,350 points
34 views

1 answer to this question.

0 votes

To get transaction details like Block Hash and Block index: web3.eth.getTransaction(txHash) 

It will take some time to miner to mine block and add to blockchain. So its not instant.

If you want to know any storage value is added/modified in blockchain to outside world, then we need to raise en event in smart contract.

Look at the below Solidity and Javascript code:

 rule PreventTransaction {
description: "prevent others executing transactions"
participant: "org.acme.trading.Employee"
operation: ALL
resource: "org.acme.trading.AssignStatus"
action: DENY
}

Javascript:

// Contract deployed address.
var contractAddress = "0x06433f4fc50423f71329597f50fb0a42cfecb11f"; 

if (typeof web3 !== 'undefined') {
     web3 = new Web3(web3.currentProvider);
} else {
     // set the provider you want from Web3.providers
     web3 = new Web3(new Web3.providers.HttpProvider("http://127.0.0.1:8545"));
}

//Open build folder and you will find contact json file copy the appropriate JSON and paste it there.
var contractABI = web3.eth.contract(/** ABI Here **/);

//Connected contract to your local network
var contract = contractABI.at(contractAddress);

//Loading booking event function.
var booking_event = web3.sha3('on_success_booking(address,string,string)');

//Watching events, when onBookingCompleted() tran's mined then event get triggered. You can get all previous events also. for that need to apply filters.
booking_event.watch((error, result) => {
   if(error){
       console.log("error",error);
   }
   console.log("Result", result); //result.args holds values, result.args.id, result.args.bookingId and result.args.emailid
 });
answered Jul 19, 2018 by Perry
• 17,010 points

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