using web3 client to interact with a smart contract?

[scutdk]

Hi, I am an experienced CLI user. And I find the web3 CLI wallet is very cool and suit well for my needs.
I've got to understand how to set up and transfer both local tokens and ERC20 tokens to another address.

My next question is how can I interact with a smart contract as a user rather than developer?
I tried to find any answer from the README.md with no luck.

There're some topics relating to write contract which I am not very sure.
Can you give some details on interacting with smart contracts , e,g, to swap GO for USDC from goswap?

I think their are two steps, approve and make the swap, right?
I don't have any abi file as I am a normal user not the developer.
How Can I do that with web3 CLI client. Thanks.

[treeder]

You need the abi to interact with a contract, to swap on GoSwap, you'll probably want the router contract so you can use this flag: --abi https://raw.githubusercontent.com/goswap/uniswap-v2-periphery/master/contracts/UniswapV2Router02.abi

The function is one of the swap ones like: swapExactTokensForTokens

For approvals, that's part of the token itself which is an ERC20/GO20 contract, so you can use --abi https://raw.githubusercontent.com/gochain/web3/master/assets/erc20.abi for the approve call.

[scutdk]

I've got some understanding of what an abi file is.
I've also went through some other web3 clients like web3.js and web3.py.
web3 go client is more convenient as it is a shell script cmd.

Is it possible to utilize sendtransaction function as I need to send hex data directly with web3 go client?
The contract is not open sourced, thus I can't get the abi file from etherescan.
I can get the hex data sent to the contract with etherscan.
I've searched the source code of web3 go client and it seems not possible to send hex data directly for now?

[treeder]

Doesn't look like call has a data parameter, but probably wouldn't be too hard to add. It's already in the replace command here: https://github.com/gochain/web3/blob/master/cmd/web3/main.go#L279

[621625]

Following

[treeder]

Potential PR: #217

[treeder]

Upgrade your web3 and give it a try now that #217 is merged. use --data flag.

[scutdk]

Try now with latest build.

It's working as designed properly. Thanks for quick update.

[621625]

@scatdk I would like to test this too. Could you perhaps paste the input you use to make the trade here?

[scutdk]

@scatdk I would like to test this too. Could you perhaps paste the input you use to make the trade here?

just copy&paste whatever data you grab from etherscan/bscscan and append to the data field. web3 c call --address <contract_address> --data <input_data_from_etherscan> .

[621625]

I tried that but the value is then incorrect. I. e. even if the original transaction had 1 Matic value the duplicate transaction will have 0 Matic value.

[treeder]

related: #232