How can I call a function in deployed contract on Ropsten Testnet when I don't have ABI and source code?

Question

For some testing I deployed several contracts on Ropsten Testnet using web3.py but now if I want to execute them or call any function from them, how can I do this? I don't have ABI as I did several contracts and its practically impossible for me to verify every single contract. I have only Transaction hash and the contract address.

Please help

Answer 1

There is (almost) no way to get the ABI if you only have the transaction hash and/or contract address.

I said almost because it is possible to reverse-engineer the contract. At least in theory. Reverse-engineering is always a difficult process and it might not work. There are some tools which attempt to do it for you but I don't really know how accurate they are.

Some more info on reverse-engineering: Is there a way to extract ABI from a deployed contract?

Just to clarify some confusion in an another answer's comments: verifying your code on Etherscan isn't really a Ethereum term. It's only functionality which was (possibly) invented by Etherscan team. It's a handy feature but it's not necessary in any way. You can publish your code in the blockchain without providing the source code to anyone.

Answer 2

You don't need the full ABI assuming you know the specific function signature you are trying to call.

I see you asked for web3.py but I'm not familiar with that. Here's the API's of interest from web3.js... hopefully you can find the equivalent in .py.

https://web3js.readthedocs.io/en/1.0/web3-eth-abi.html#encodefunctioncall https://web3js.readthedocs.io/en/1.0/web3-eth.html#sendtransaction

So the code looks something like:

let call = web3.eth.abi.encodeFunctionCall({
    name: 'myMethod',
    type: 'function',
    inputs: [{
        type: 'uint256',
        name: 'myNumber'
    },{
        type: 'string',
        name: 'myString'
    }]
}, ['2345675643', 'Hello']);
let tx = await web3.eth.sendTransaction(call, {to: contract_address})

hth

Answer 3

https://ropsten.etherscan.io/address/0x479955ee1b96bc0b6fff39317e567c373910e39f#code

Replace "0x479955ee1b96bc0b6fff39317e567c373910e39f" with address of your contract, it will show you the source code and ABI, if it is deployed over Ropsten network.