Ethereum: Web3 contract (React) – Safeetr20 low level called with token ERC20 (USDT)

As a developer who works on an intelligent contract or a web3 application, you are probably familiar with the concept of interacting with different blockchain networks. In this article, we will explore a problem that has been reported by several users and developers.

The problem

The problem is related to the low -level calling mechanism Safeerc20 in the Ethereum web3 fipas. In particular, when using a contract built on Ethereum (such as Elderscan), the attempt to call a function with an ERC20 token (as USDT) triggers a failure.

The symptoms

The symptoms are as follows:

  • The smart contract works well if you try to use it with ETH (Ethereum).

  • However, when using the same contract on an ERC20 token as USDT, problems are encountered.

  • The error message generally indicates that the call has not succeeded, but does not provide specific details.

The solution

To solve this problem, you have some options:

  • Use a different token : instead of trying to use the ERC20 token (USDT), try to use another token that Ethereum supports, as if you give or links.

  • implements a Fallback

    Ethereum: Web3 Contract (React) - SafeERC20 Low Level Call failed with ERC20 Token (USDT)

    mechanism: it is possible to implement a bankback mechanism in the contract that tries to call the function with an ERC20 token before resorting to hat if necessary.

Example code

Here is a Snappet of example in solidity

Solidity `

Pragma solidity ^0.8.0;

Safeerc20fallback contract {

Callfunction () public function {

// First of all, try to call the function with ETH

If (msg.sender.balance> 1010 * 18) {

// In case of success, return the value of the variable

Uint256 result = msg.value / 10 ** 18;

Return result;

}

// If you haven’t succeeded, try calling the function with an ERC20 token

Address [] tokens memory = [address (0x89f8c7ce9e77fbc2a3bbbbbbbb5da1bf6cc4bfc94ce)];

For (Uint256 i = 0; i

// Get the token contract

Token contract = token (address (token [i]));

// Try to call the function with the token

Uint256 result = contracttt.callfunction ();

// In case of success, return the value of the variable

If (result> 0) {{{

Return result;

}

}

// If he hasn’t succeeded in both methods, restore the transaction

restore ();

}

}

Token Stuct {

Public address tokenaddress;

}

``

Conclusion

In this article, we have explored a problem that has been reported by several users and developers relating to low -level calls Safeerc20 who fail with the ERC20 tokens when using Ethereum. We also provided an example of code in solidity which shows how to implement a bankback mechanism for such cases.

By understanding the cause of the problem and the implementation of an unable solution, you should be able to solve these problems and continue to develop the intelligent contract or the web3 application.

(Visited 1 times, 1 visits today)