owner only view function

Question

Is it possible to make a function only callable by owner but restricted to view? I tried something like that.

function getUserTokenBalance(address user) public view onlyAdmin returns (uint256) {
    return balance[user];
}

Calling this method from web3 like:

contract.methods
 .getUserTokenBalance('0x06bf3b021f10712655a8786f2bFfF11ddE0ea21B')
 .call({ from: account.address })
 .then((data) => {
   console.log('balance: ', data);
 })
.catch((err) => {
  console.log('error', err);
});

returns some weird long number as string 3963877391197344453575983046348115674221700746820753546331534351508065746944

I guess it's not working because I have to send a transaction so the smart contract can verify me as the owner. However, what I want to achieve is to query some state in the smart contract without paying any fees.

Answer 1

Since everything is public on the blockchain when you deploy a smart contract, you cannot make a field that's hidden from everyone except the owner unfortunately. For more info on this, check out this question. The closest you can get is by limiting some functionality to the owner, like this for example:

  // Owner address of the contract
  address public owner;

  constructor() public {
    owner = msg.sender;
  }

   // A owner-only callable function
   function onlyOwner () public{
     require(msg.sender == owner, "This can only be called by the contract owner!");
     // Do stuff
   }