Call function from deployed contract

Question

I have a deployed contract (contract A) which should act as a storage (let's say 0xD7ACd2a9FD159E69Bb102A1ca21C9a3e3A5F771B).

Now from my ERC20 Token contract (contract B), I am calling approve to the contract A to allow it to "withdraw" my tokens.

Would it be possible to call trasnferFrom of contract A inside another function of contract B?

I am trying with (inside the code of B)

address A = 0xD7ACd2a9FD159E69Bb102A1ca21C9a3e3A5F771B;
...
approve(A,_amount);
A.call(bytes4(keccak256("transferFrom(address, address, uint256)")), (_B, msg.sender, _amount));

But it doesn't work since I am giving too many arg to the call function.

What would be the best way to transfer automatically my token (contract A) to a deployed ERC20 contract from within the contract B itslef?

EDIT

So on my receiver contract A, I added the function:

    function getTokens (address from, uint256 value) public returns (bool) {
        transferFrom(from, address(this), value);
        return true;
    }

And on my sender contract B I am calling:

    address contract_address = 0x09943Fa8DD32C76f7b880627a0F6af73e8f5A595 ;
     
...
        approve(contract_address, _value);
        contract_address.call(abi.encode("getTokens(address, uint256)",msg.sender, _value));
...

But even if tx is succesfull, when I check balance of contract A, it's 0. I don't know exactly what I am missing.

Answer 1

I'm not 100% sure I understood your scenario correctly, but let's try to answer.

No you can't "push" tokens with transferFrom. That function needs to be called by the contract / EOA which wants to get the tokens (and has allowance to withdraw).

If you want to push tokens you can use the transfer function, but that has different semantics, as you probably know.

What you can do is add functionality in whatever contract wants the tokens, for example a new function getTheTokens. That function could then be called by whatever other contract and that function calls the transferFrom.