需要从任何区块链上的区块中检索交易

Question

I am assigned this task that I have to retrieve transactions from a block on any blockchain network and create a log file using GO programming language. I have searched ethereum blockchain and tried to do the same using geth client but it makes me download the whole blockchain which is more than 100gb. So my question is, is there any way to access a block on any blockchain and read it's transactions and use the same to create a log file. I just need some head up. Help appreciated. thanks

Answer 1

Please use truffle Ganache ethereum client. Download from http://truffleframework.com/ganache/

I have created NodeJS code to read transaction from latest block. Step 1: Install nodeJS and NPM if not installed in your machine. Step 2: Create new folder "demo" and create new package.json file. Place below code in package.json file

    {
  "name": "transactionRead",
  "version": "1.0.0",
  "description": "Blockchain Transaction Read",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "dependencies": {
    "web3": "^0.19.0"
  },
  "author": "",
  "license": "ISC"
}

3. Create index.js file and place below code.

   var Web3 = require('web3'); var fs = require('fs'); //Create a log file to store transaction fs.writeFile('log.txt', 'Hello Transaction!', function (err) { if (err) throw err; console.log('Created!'); }); // create an instance of web3 using the HTTP provider. // NOTE in mist web3 is already available, so check first if it's available before instantiating 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://localhost:7545 ")); }

   // Watch for blockchain transaction, if found changes fetch the transaction data var filter = web3.eth.filter('latest', function (error, blockHash) { if (!error) { var block = web3.eth.getBlock(blockHash, true); if (block.transactions.length > 0) { console.log("found " + block.transactions.length + " transactions in block " + blockHash); fs.appendFile('log.txt', JSON.stringify(block.transactions), function (err) { if (err) throw err; console.log('Updated!'); }); console.log(JSON.stringify(block.transactions)); } else { console.log("no transaction in block: " + blockHash); } } });

   Step 4: Run $ node index.js command through command line

   Let me know if need any help. Thanks,