Calling function in one contract from another contract in private blockchain by Geth

Question

I have problem with smart contract development using Remix solidity in private blockchain by Geth. I have two smart contracts such as Factory contract and Contract contract.

I create the Factory contract and then I call the createContract and getContract function, it works normally but when i call the getNum function I can not get the number.

I run this code in Remix solidity by JavaScript VM and Test network by Ganache or TestRPC work fine but when i use it with Private blockchain using Geth it has this problem

Here is my code.

contract Factory {
  address[] newContracts;

  function createContract(uint num) {
    address newContract = new Contract(num);
    newContracts.push(newContract);
  }

  function getContract() view public returns(address[]) {
    return newContracts;
  }

  function getNum(address _add) view public returns(uint) {
    return Contract(_add).getNum();
  }
}


contract Contract {
  uint public Num;

  function Contract(uint num) {
    Num = num;
  }

  function getNum() public returns(uint) {
    return Num;
  }
}

Answer 1

In Contract add view-modifier to getNum

function getNum() public view returns(uint) {
    return Num;
}

Your calls worked in ganache/testrpc/remix because the test EVM is synchronous in nature. I.e., you'll be able to get return values of transactions, since sendTransaction calls are executed instantly.