问无法从智能合约获取客户端中的状态变量

EN

pragma solidity ^0.4.24;

import './KhananiToken.sol';

contract KhananiTokenSale {
    address admin;
    KhananiToken public tokenContract;
    uint256 public tokenPrice;
    uint256 public tokensSold;

    event Sell(
        address   _buyer,
        uint256  _amount
    );

    constructor (KhananiToken _tokenContract, uint256 _tokenPrice ) public {
        //Assign an Admin
        admin = msg.sender; //address of person how deployed the contract

        tokenContract = _tokenContract;
        tokenPrice = _tokenPrice;
    }

    function multiply(uint x, uint y) internal pure returns(uint z) {
        require(y == 0 || (z = x * y) / y == x);
    }

    function buyTokens(uint256 _numberOfTokens) public payable {
        require(msg.value == multiply(_numberOfTokens , tokenPrice));

        require(tokenContract.balanceOf(this) >= _numberOfTokens);        

        require(tokenContract.transfer(msg.sender, _numberOfTokens));        

        tokensSold += _numberOfTokens;

        Sell(msg.sender, _numberOfTokens);
    }

}

module.exports = function(deployer) {
  var tokenSupply = 1000000;
  var tokenPrice = 1000000000000000; // is 0.001 Ehter

  deployer.deploy(KhananiToken, tokenSupply).then(function(TokenAddress){
    return  deployer.deploy(KhananiTokenSale, TokenAddress.address, tokenPrice);
  }); //1000000 it the inital token supply

};

App.contracts.KhananiTokenSale.deployed().then(function(instance){
      khananiTokenSaleInstance = instance;
      return instance.tokenPrice();
    }).then(function(tokenPrice){
      console.log('tokenPrice',tokenPrice)
      console.log('tokenPrice',App.tokenPrice)
      App.tokenPrice = tokenPrice;
      //$('.token-price').html(App.tokenPrice)
    })