Via Geth commandline I can get my smartcontract token balance with:
var mytest = eth.contract([{interface}]).at(contract address);
mytest.balanceOf(eth.accounts[0])
>998
I want to present the token balance on my website. How can I do that?
I tried JSON-RPC and several methods like eth_getTransactionByHash, but can't find out how to get the balance.
Use web3.js to present the balance on your website.
Geth's console, where you were able to obtain the token balance, is Javascript and uses web3.js under the hood, so your website code will be almost identical.
Otherwise, with JSON-RPC you have to use eth_call and you have to ABI encode the function you are calling and its parameters. It is much more complicated, for an example see:
How to call a contract method using the eth_call JSON-RPC API
If server-side rendering is desired, that design decision could be examined because a user should be able to run a decentralized application without a server: Swarm and IPFS are technologies to keep in mind as the direction DApps will likely take.
With these details: var MyContract = eth.contract([{interface}]). And: var tokens = MyContract.at("MyAddress").balanceOf(eth.accounts[0]); console.log(tokens);
– Jeroen May 16 '16 at 10:38Adding to answer of @eth♦ and comment from @Jeroen
Get Smartcontract Token balance with web3 1.0.0-beta.31
In 1.0.0-beta... most is handled via Promises now, hence you could do:
var mytest = new web3.eth.Contract({interface}, '0x123....', {
from: '0x456...', // default from address
gasPrice: '20000000000' // default gas price in wei, 20 gwei in this case
});
mytest.methods.balanceOf('0x456...').call()
.then(function(result){
//the result holds your Token Balance that you can assign to a var
var myTokenBalance = result;
return result;
});
{interface} is the ABI of your Contract 0x123.....0x123.... is the address of your Contract.0x456.... is the address of your Ethereum Account that holds
the Tokens (i.e. the ETH account you wish to retrieve its Token Balance from)Don't forget to add the new before web3.eth.Contract(....)
@Jeroen That way you won't get the error
MyContract.at is not a function
anymore.
Note: I am using the IPC Provider geth.ipc to interact with my node (as I am on the same PC, localhost, hence more save instead of using HTTP request).
if (typeof web3 !== 'undefined') {
web3 = new Web3(web3.currentProvider);
} else {
var net = require('net');
var web3 = new Web3('/home/yourHomeFolder/.ethereum/geth.ipc', net);
};
Edit: For reference following the ABI JSON ( web3.eth.Contract({interface} ) I am using for my smart contract, being myContractABI my {interface}:
myContractABI = [
{
"constant": false,
"inputs": [
{
"name": "newSellPrice",
"type": "uint256"
},
{
"name": "newBuyPrice",
"type": "uint256"
}
],
"name": "setPrices",
"outputs": [],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "name",
"outputs": [
{
"name": "",
"type": "string"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_spender",
"type": "address"
},
{
"name": "_value",
"type": "uint256"
}
],
"name": "approve",
"outputs": [
{
"name": "success",
"type": "bool"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "totalSupply",
"outputs": [
{
"name": "",
"type": "uint256"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_from",
"type": "address"
},
{
"name": "_to",
"type": "address"
},
{
"name": "_value",
"type": "uint256"
}
],
"name": "transferFrom",
"outputs": [
{
"name": "success",
"type": "bool"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "decimals",
"outputs": [
{
"name": "",
"type": "uint8"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_value",
"type": "uint256"
}
],
"name": "burn",
"outputs": [
{
"name": "success",
"type": "bool"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "sellPrice",
"outputs": [
{
"name": "",
"type": "uint256"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": true,
"inputs": [
{
"name": "",
"type": "address"
}
],
"name": "balanceOf",
"outputs": [
{
"name": "",
"type": "uint256"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "target",
"type": "address"
},
{
"name": "mintedAmount",
"type": "uint256"
}
],
"name": "mintToken",
"outputs": [],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_from",
"type": "address"
},
{
"name": "_value",
"type": "uint256"
}
],
"name": "burnFrom",
"outputs": [
{
"name": "success",
"type": "bool"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "buyPrice",
"outputs": [
{
"name": "",
"type": "uint256"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "owner",
"outputs": [
{
"name": "",
"type": "address"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": true,
"inputs": [],
"name": "symbol",
"outputs": [
{
"name": "",
"type": "string"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [],
"name": "buy",
"outputs": [],
"payable": true,
"stateMutability": "payable",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_to",
"type": "address"
},
{
"name": "_value",
"type": "uint256"
}
],
"name": "transfer",
"outputs": [],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [
{
"name": "",
"type": "address"
}
],
"name": "frozenAccount",
"outputs": [
{
"name": "",
"type": "bool"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "_spender",
"type": "address"
},
{
"name": "_value",
"type": "uint256"
},
{
"name": "_extraData",
"type": "bytes"
}
],
"name": "approveAndCall",
"outputs": [
{
"name": "success",
"type": "bool"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": true,
"inputs": [
{
"name": "",
"type": "address"
},
{
"name": "",
"type": "address"
}
],
"name": "allowance",
"outputs": [
{
"name": "",
"type": "uint256"
}
],
"payable": false,
"stateMutability": "view",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "amount",
"type": "uint256"
}
],
"name": "sell",
"outputs": [],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "target",
"type": "address"
},
{
"name": "freeze",
"type": "bool"
}
],
"name": "freezeAccount",
"outputs": [],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"constant": false,
"inputs": [
{
"name": "newOwner",
"type": "address"
}
],
"name": "transferOwnership",
"outputs": [],
"payable": false,
"stateMutability": "nonpayable",
"type": "function"
},
{
"inputs": [
{
"name": "initialSupply",
"type": "uint256"
},
{
"name": "tokenName",
"type": "string"
},
{
"name": "tokenSymbol",
"type": "string"
}
],
"payable": false,
"stateMutability": "nonpayable",
"type": "constructor"
},
{
"anonymous": false,
"inputs": [
{
"indexed": false,
"name": "target",
"type": "address"
},
{
"indexed": false,
"name": "frozen",
"type": "bool"
}
],
"name": "FrozenFunds",
"type": "event"
},
{
"anonymous": false,
"inputs": [
{
"indexed": true,
"name": "from",
"type": "address"
},
{
"indexed": true,
"name": "to",
"type": "address"
},
{
"indexed": false,
"name": "value",
"type": "uint256"
}
],
"name": "Transfer",
"type": "event"
},
{
"anonymous": false,
"inputs": [
{
"indexed": true,
"name": "from",
"type": "address"
},
{
"indexed": false,
"name": "value",
"type": "uint256"
}
],
"name": "Burn",
"type": "event"
}
];
