Metamask: Understanding transfers and approval ERC-20
As we continue to build applications that interact with the Ethereum blockchain, it is essential to understand how metamask makes it easy to safely transactions between the browser and the contracts. In this article, we will dive into the ERC-20 transfers world and examine the concept of approval.
ERC-20: Standard Smart Treaty for Token Transactions
In 2015, Ethereum introduced the ERC-20 standard as a set of rules and protocols that regulate the creation, trading and transmission of tokens to blockchain. These tokens are digital assets that can be stored, transmitted and used on different platforms.
ERC-20 tokens have gained considerable popularity due to their versatility and ease of use. They can represent different types of digital assets such as cryptomena such as bitcoin or ethereum, as well as financial instruments such as stabbleins and tokens tokens.
Transferring tokens ERC-20 from browser to contract
When the user wants to transfer the ERC-20 token from the browser to the contract address, he interacts with the Metamask wallet. Here’s what happens under the hood:
- The user initiates the transaction by sending a “transfer” message to the Ethereum network.
- Metamask verifies the identity of the sender and ensures that the transaction is allowed by their private key.
- After verification, the transaction is transmitted to the blockchain, where it is verified by nodes such as the gas nodes of the L1 or the layer of layers 2 (eg optimism or polygon).
- If the transaction is valid, the address of the contract with the receiving token ERC-20 is identified and the transfer is made.
Approval: Key to secure transactions
To facilitate safe transactions, Metamask is introducing a concept called approval. Approval allow users to determine the conditions under which they approve or refuse a transaction. This gives the transaction another layer of safety, ensuring that the transfers can only be initiated by authorized parties.
There are two types of approval:
- Approval types
: Users can choose from predefined approval types, for example:
* True: Use the transfer.
* False: Reject the transfer.
- Conditional approval : Users may also determine the conditions for which transactions are allowed or rejected. For example, the user can only approve the transfers when the ERC-20 tokens have a minimum balance.
How to apply for code approval on the user’s side
If you want to enable ERC-20 transfer using metamask and approval by the user, you can follow the following steps:
- Initialize your Metamask wallet with your private key.
- Send a transaction to start transmission (eg transmission method).
- Define the conditional approval using the “Approvaltype” field (eg “TRUE” or specify the conditions for approval (eg the minimum balance requirement).
Here’s an example of a fragment of code in the fortress:
`Solidity
Pragma of solidity ^0.8.0;
Import “
MyContract {
use Safeerc20 for (address, UINT256);
Token Struct {
address tokenaddress;
UINT256 balance;
}
Function transfer (address recipient, amount of Uint256) public {
// Define the type of approval
bool approved = false;
// Enter the conditions for approval
IF (Bilant> 10) {// Minimum Request for Balance
// to approve the transfer with conditional consent
request (approved, “transfer not allowed”);
return;
}
// Initiate the transaction using the API Metamask interface
// …
}
}
`
In this example, users may approve or reject transactions based on their conditions.