Synchronous requests are not supported by the IPC provider

Question

I was trying to connect to my node via IPC using web3_ipc. But i got hit by:

 You tried to send "eth_getBalance" synchronously. Synchronous requests are not supported by the IPC provider.

My code is as:

var web3_extended = require('web3_ipc');
var path = require('path');
var absolutePath =  path.relative('./','/home/pr.singh/.ethereum/geth.ipc');
var options = {
  host : absolutePath,
  // host: 'http://10.10.23.139:8013',
  ipc : true,
  personal: true, 
  admin: true,
  debug: false
};

var web3 = web3_extended.create(options);

exports.checkBalance = function(req, res) {
    var bal = req.body.balance;
                var accountBalance=web3.eth.getBalance(bal).toNumber(); 
                console.log(accountBalance);
}

If I connect using rpc, everything works good but while connecting via IPC , I am getting error. Any help?

Answer 1

It seems that IPC doesn't support synchronous call which make sense in term of non-blocking code execution in this kind of architecture. Metamask has the same constraint.

Anyway, good practice in my opinion is to use asynchronous call with callback method: You can directly pass the callback function in the Web3 call:

exports.checkBalance = function(req, res) {
    var bal = req.body.balance;

    web3.eth.getBalance(bal, function(error, result) {
        // This is executed once I got the response
        console.log("Response received");

        if(error != null) {
            console.error(error);
            return;
        }

        var accountBalance = result.toNumber();
        console.log(accountBalance);
    }); 

    // This is executed just after the request is sent no matter the response
    console.log("Request sent");
}

Or for a better re-usability, define you callback function and inject it as a parameter:

exports.checkBalance = function(req, res) {
    var bal = req.body.balance;

    web3.eth.getBalance(bal, exports.checkBalanceCallback); 
}

exports.checkBalanceCallback = function(error, result) {

     if(error != null) {
        console.error(error);
         return;
     }

    var accountBalance = result.toNumber();
    console.log(accountBalance);
}

EDIT: Just edited my answer, according to the Web3 documentation about callback the method signature is function(error, result);