robbertjansw / php-erc20

The simple way to interact with Ethereum ERC20 token.

Simple Ethereum ERC20 token php library

This library provides simple way to interact with Ethereum ERC20 token.
By default, supports all ERC20 Standard functions (like balanceOf, transfer, transferFrom, approve, allowance, decimal, name, ...) also can be extends to support other contracts as well.

Installation

composer require lessmore92/php-erc20

Usage

There are two ways to use:

1- Make a new class for your token and specified their functions

2- Use general class with all standard functions

See below to find out more

1-Make a new class for your token

Simply create a new class inherits from \Lessmore92\Ethereum\Foundation\StandardERC20Token

in below sample we create a new class for Tether (USDT)

class USDT extends \Lessmore92\Ethereum\Foundation\StandardERC20Token 
{
    protected $contractAddress = "0xdac17f958d2ee523a2206206994597c13d831ec7";  
}

Then for use create new instantiate from your class and

$tether = new USDT("https://mainnet.infura.io/v3/API_KEY");
var_dump($tether->name());
var_dump($tether->decimals());

2- Use general class

$token = new \Lessmore92\Ethereum\Token("0xdac17f958d2ee523a2206206994597c13d831ec7", "https://mainnet.infura.io/v3/API_KEY");
var_dump($token->name());

Connection Timeout

Connection timeout can be set by last parameter of token class

$timeout  = 3; //secs
$tether = new USDT("https://mainnet.infura.io/v3/API_KEY",$timeout);

OR

$timeout  = 3; //secs
$tether = new \Lessmore92\Ethereum\Token("0xdac17f958d2ee523a2206206994597c13d831ec7", "https://mainnet.infura.io/v3/API_KEY", $timeout);

Ethereum RPC Client

For connect to Ethereum blockchain you need an Ethereum node; Infura is a simple and fast solution, however you can launch you Geth node

ERC20 Token transferFrom

ERC20 transaction fee needs to be paid in ETH. In some situation your app needs to pay this fee behalf of user.
Suppose, user A have a key pair (private, public) and all their transaction is limited to usdt. User A needs to send 10 usdt, but he/she haven't ETH to pay transaction fee.
In these cases your app should pay fee behalf of users.
transferFrom is a good solution in these cases.

transferFrom Flow:

1.First, Using approve method to grant permission to a delegator.
2.Then, Using transferFrom method to make transaction behalf of user.

In Action

$owner_private = '0xcf29c83a88e23d0b9e676beca426490bf79aca71e9d24f79a99d30c48292e1e3';
$owner_address = '0xA7e5F270c27E9d33911EE7D50D8E814f793d2760';

$myapp_private = '0xa6b6be193bfeac6160178ee6e1435609ae566a9054715e0802e4c3b39bb94e83';
$myapp_address = '0x8dC9b3c20795815aa063FEdBE8E564566CEc1893';

$to_address = '0x245013F05DdA116142Ca8db205ec4F8C780E3DcB';

//by this method we allow $myapp_address to send upto 99999 token behalf of $owner_address
$approve_tx    = $token->approve($owner_address, $myapp_address, 99999);
$approve_tx_id = $approve_tx->sign($owner_private)
                            ->send()
;


//the magic is here, $myapp_address send 10 tokens behalf of user and $myapp_address pay transaction fee
$transfer_tx    = $token->transferFrom($myapp_address, $owner_address, $to_address, 10);
$transfer_tx_id = $transfer_tx->sign($myapp_private)
                              ->send()
;

allowance to check how much transferFrom remain

$remain = $token->allowance($owner_address, $myapp_address);

Notices:
approve method not need to be used on every transaction.
To revoke transferFrom permission call $token->approve($owner_address, $myapp_address, 0) by amount 0.