flutter_web3_provider

Description:

flutter web3 provider

flutter_web3_provider #
Flutter wrapper for using web3 providers, ie: accessing window.ethereum.
NOTE: This is for web only!
Getting Started #
For full example, see: https://github.com/gochain/flutter_web3_provider/blob/main/example/lib/main.dart
Add import import 'package:flutter_web3_provider/ethereum.dart';
Then you can access it just be using the ethereum variable.
if(ethereum != null){
// then an ethereum provider was injected
print(ethereum.selectedAddress);
}
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Ask user to connect their wallet:
RaisedButton(
child: Text("Connect Wallet"),
onPressed: () async {
var accounts = await promiseToFuture(
ethereum.request(RequestParams(method: 'eth_requestAccounts')));
print(accounts);
String se = ethereum.selectedAddress;
print("selectedAddress: $se");
setState(() {
selectedAddress = se;
});
},
)
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Using ethers.js #
Add ethers.js to web/index.html.
eg:
<script src="https://cdn.ethers.io/lib/ethers-5.0.umd.min.js" type="application/javascript"></script>
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Import package:
import 'package:flutter_web3_provider/ethers.dart';
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Then create an ethers provider:
// For a read-only provider:
var provider = JsonRpcProvider("https://rpc.gochain.io");
// For a read-write provider (ie: metamask, trust wallet, etc)
var web3 = Web3Provider(ethereum);
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Then you can do things like check balance and submit transactions, etc:
var abalanceF = promiseToFuture(web3.getBalance(ethereum.selectedAddress));

Future tx = promiseToFuture(web3.Signer().sendTransaction(TxParams(
to: to,
value: "0x" +
BigInt.parse(toBase(amount, 18).toString()).toRadixString(16))));
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Or use a contract:
const erc20Abi = [
// Some details about the token
"function name() view returns (string)",
"function symbol() view returns (string)",

// Get the account balance
"function balanceOf(address) view returns (uint)",

// Send some of your tokens to someone else
"function transfer(address to, uint amount)",

// An event triggered whenever anyone transfers to someone else
"event Transfer(address indexed from, address indexed to, uint amount)"
];
var contract = Contract(contractAddress, erc20Abi, web3);
// call balanceOf function
var usdcBalanceF = promiseToFuture(
callMethod(contract, "balanceOf", [ethereum.selectedAddress]));

// to make a write transaction, first get the signer (this will use metamask/wallet)
contract = contract.connect(web3.getSigner()); // uses the connected wallet as signer
// then call the function:
var res =
await promiseToFuture(callMethod(contract, "transfer", [
'0x39C5190c09ec04cF09C782bA4311C469473Ffe83',
"0x" + amount.toString()).toRadixString(16)
]));
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If you need to additional overrides like set gas price or passing the value param, you can add one extra param in the array with those fields, eg:
var res = await promiseToFuture(callMethod(
contract, "transfer", ['0x39C5190c09ec04cF09C782bA4311C469473Ffe83', "0x" + amount.toString()).toRadixString(16),
TxParams(value: "1000000000000000000")]));
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NOTES:

If you're using the human readable ABI's (ethers.js feature) like above, use uint, not uint256 even if the real abi is a uint256.
There are some common functions on the Contract, but you can also call any method using callMethod like above.