Aleph Zero Signer integration
Learn how to integrate Aleph Zero Signer into web apps.
In this tutorial, we create a simple web app integrated with the Aleph Zero Signer. This app will:
- import and display accounts from the Signer;
- sign a simple transfer transaction using one of those accounts.
node14.18+ or 16+ (required to usevitewithreact: your dependencies may vary if you choose to use a different framework).
Run:
npm create vite@latest signer-integration -- --template react-ts
You will then be able to start the dev server like this:
cd signer-integration
npm install
npm run dev
Aleph Zero Signer exposes the polkadot.{js} dapp extension library API. You can check out their docs here.
npm install @polkadot/extension-dapp
First, let's make sure Signer was successfully injected into our website.
If Signer (or any other extension supporting this API) is available, it is added to the
window.injectedWeb3 object.You can test that by running this example:
npm run dev
and, using your browser's developer console, inspect the
window.injectedWeb3 object to see if Signer is registered.
Firefox developer console screenshot
Common pitfalls/troubleshooting
- Signer extension wasn't successfully installed;
- Signer is disabled;
- Make sure your site is served from localhost, 127.0.0.1, or over https:// - Signer isn't injected on other sites served over http://.
Now, we will enable injected extensions as the API can handle more than one extension at a time–in our case, it's just the Signer.
We will be using
web3Enable - a util function from @polkadot/extension-dapp. It enables the connection and returns a list of all injected extensions.We're going to call this method in the
onClick handler of the 'Connect account' button:import { web3Enable } from "@polkadot/extension-dapp";
type InjectedExtension = Awaited<ReturnType<typeof web3Enable>>[number];
const [extensions, setExtensions] = useState<InjectedExtension[]>([]);
const loadAccountsFromExtensions = async () => {
// extension-dapp API: connect to extensions; returns list of injected extensions
const injectedExtensions = await web3Enable(APP_NAME);
setExtensions(injectedExtensions);
};
<button onClick={loadAccountsFromExtensions}>
Connect to extensions
</button>
APP_NAME is a string - the name of the app that is trying to connect. This is how your app is going to be represented inside the Signer.You have to call
web3Enable before any other utility functions.Now, after clicking the button and going through the
Your privacy is protected screen, you should see one of these pop-ups:
No accounts screen
Connect app screen with one account
Add an account to Signer if you haven't already, and make sure you select the checkbox next to it when connecting. Connecting an account means it will be available on a website–we'll be able to get the account information and initiate signing transactions.
You can change connected accounts by going to:
settings (top left corner) > Trusted apps > <Your app>Now we can use
web3Accounts helper function to get all the accounts provided by the Signer:import { web3Accounts } from "@polkadot/extension-dapp";
type InjectedAccountWithMeta = Awaited<ReturnType<typeof web3Accounts>>[number];
const [accounts, setAccounts] = useState<InjectedAccountWithMeta[]>([]);
// extension-dapp API: get accounts from extensions filtered by name
const accounts = await web3Accounts(
{ extensions: ["aleph-zero-signer"] }
);
setAccounts(accounts);
<article>
<h2>Signer accounts</h2>
<ul>
{accounts.map(({ address, meta: { name } }) => (
<li key={address}>
<strong>{name || "<unknown>"}</strong> {address}
</li>
))}
</ul>
</article>
Above, we're filtering to get only the accounts from the Signer, but you might choose to include all accounts.
Since, in this example, we will make transactions on the Aleph Zero Testnet, we will need two accounts and some funds (TZERO). Create a second account in the Signer. Accounts have associated networks, and we want both accounts to have the Aleph Zero Testnet selected. You can either select it in the account creator or change it later in the settings.
We should be able to filter the accounts over the selected network. To that end,
web3Accounts has a genesisHash parameter available, and for the Aleph Zero Testnet, we want:// extension-dapp API: get accounts from extensions filtered by name and chain
const accounts = await web3Accounts({
extensions: ["aleph-zero-signer"],
genesisHash:
"0x05d5279c52c484cc80396535a316add7d47b1c5b9e0398dd1f584149341460c5",
});
With the accounts ready, we need to set them up with some TZERO (the Aleph Zero Testnet currency). To do so, copy the first account address and paste it into the address field in the Testnet Faucet. You'll need to solve a captcha, and the system will transfer some TZERO to your account. You can check your accounts' balances e.g. in https://test.azero.dev/#/accounts (which, incidentally, is also an example of a Signer integration).
npm install @polkadot/api
We'll need to set it up and initialize it using the Aleph Zero Testnet websocket:
import { ApiPromise, WsProvider } from "@polkadot/api";
const ALEPH_ZERO_TESTNET_WS_PROVIDER = new WsProvider(
"wss://ws.test.azero.dev"
);
const API_PROMISE = ApiPromise.create({
provider: ALEPH_ZERO_TESTNET_WS_PROVIDER,
});
const [api, setApi] = useState<ApiPromise>();
useEffect(() => {
API_PROMISE.then(setApi);
}, []);
Next, we are going to sign a simple transfer transaction. For the sake of simplicity, we are going to transfer
50 TZERO from the first account to the second one.Note that we're using the big number implementation from
@polkadot/util to make sure we don't exceed JavaScript's safe integer range.npm install @polkadot/util
The balance on–chain is kept in pico TZERO (10-12), so we need to adjust the transferred value. Instead of hard-coding the units here, we can get this information from the
api.import { web3FromAddress } from "@polkadot/extension-dapp";
import { BN } from "@polkadot/util";
const makeTransfer = async () => {
const [first, second] = accounts;
// extension-dapp API: get address's injector
const firstAddressInjector = await web3FromAddress(first.address);
const transferAmount = new BN(50);
const unitAdjustment = new BN(10).pow(new BN(api.registry.chainDecimals[0]));
const finalAmount = transferAmount.mul(unitAdjustment);
await api.tx.balances
.transfer(second.address, finalAmount)
.signAndSend(first.address, { signer: firstAddressInjector.signer });
};
<button onClick={makeTransfer}>Make transfer</button>;
After clicking the button, you should see the Signer pop-up:
Transaction authorization screen
Lastly, you can confirm and check your accounts' balances in https://test.azero.dev/#/accounts.
Just because the transaction Promise doesn't throw an exception, it doesn't mean it succeeded - see https://polkadot.js.org/docs/api/cookbook/tx/#how-do-i-get-the-decoded-enum-for-an-extrinsicfailed-event.
We hope you've enjoyed this tutorial, and now you know how to smoothly integrate your app with the Signer.
For other tutorials, head over to alephzero.org/developers
If you need any other help, make sure to join our Discord!
Feel free to use those icons when integrating Signer with your app:
