Burnt (XION)
Ask or search…
K

Fee Granting

Learn to create a gas-less experience for your end users

Demonstrating Fee Allowance

This guide outlines how to grant a fee allowance, so that you can enable a gas-less experience for your end users. This guide also demonstrates how to validate its functionality by sending tokens back using AAClient. The process involves:
  1. 1.
    Initial Setup: Creating client instances for a funding account and a recipient account.
  2. 2.
    Granting Fee Allowance: Allowing the recipient account to use the funding account's resources for transaction fees.
  3. 3.
    Validating Fee Allowance: Sending a token from the recipient account to the funding account to demonstrate the successful fee grant.
Initial Setup
Begin by initializing client instances for both accounts using user-provided private keys:
import { AAClient } from "@burnt-labs/signers";
// These are used in the following code examples.
import { MsgGrantAllowance } from "cosmjs-types/cosmos/feegrant/v1beta1/tx";
import { BasicAllowance } from "cosmjs-types/cosmos/feegrant/v1beta1/feegrant";
export async function buildClient(
key: string
): Promise<[AAClient, AccountData]> {
const signer: OfflineDirectSigner = await DirectSecp256k1Wallet.fromKey(
fromHex(key),
burntChainInfo.bech32Config.bech32PrefixAccAddr
);
const [accountData] = await signer.getAccounts();
const client = await AAClient.connectWithSigner(
// This can be any RPC endpoint.
"https://rpc.xion-testnet-1.burnt.com:443",
signer
);
return [client, accountData];
}
const [fundingAccountClient, fundingAccount] = await buildClient("<private_key_of_funding_account>");
const [recipientAccountClient, recipientAccount] = await buildClient("<private_key_of_recipient_account>");
Granting Fee Allowance
Grant a fee allowance from the funding account to the recipient account:
// Construct the grant allowance message
const msgGrantAllowance = {
typeUrl: "/cosmos.feegrant.v1beta1.MsgGrantAllowance",
value: MsgGrantAllowance.fromPartial({
granter: fundingAccount.address,
grantee: recipientAccount.address,
allowance: {
typeUrl: "/cosmos.feegrant.v1beta1.BasicAllowance",
value: BasicAllowance.encode(
BasicAllowance.fromPartial({
spendLimit: [
{
denom: "uxion",
amount: "<amount of token to grant>",
},
],
expiration: {
seconds: Math.floor((Date.now() + <Number of seconds until grant expires>) / 1000),
},
})
).finish(),
},
}),
};
// Send the grant allowance transaction
const grantResponse = await fundingAccountClient.signAndBroadcast(
fundingAccount.address,
[msgGrantAllowance],
defaultFee,
"Granting fee allowance to recipient account"
);
Validating Fee Allowance
To confirm the fee allowance, send a token back from the recipient account to the funding account:
// Construct the send token message
const msgSend = {
typeUrl: "/cosmos.bank.v1beta1.MsgSend",
value: {
fromAddress: recipientAccount.address,
toAddress: fundingAccount.address,
amount: [
{
denom: "uxion",
amount: "1",
},
],
},
};
// Send the token transaction
const sendResponse = await recipientAccountClient.signAndBroadcast(
recipientAccount.address,
[msgSend],
{
...defaultFee,
granter: fundingAccount.address,
},
"Returning token to funding account"
);
console.log("sendResponse", sendResponse);
This complete example shows how to set up a fee allowance and verify its success through a token transaction.
Last modified 1mo ago