NextJS Dapp Template

• multiversx-nextjs-dapp.netlify.com

Nextjs alternative to the dapp-core. Based on Elven Tools Dapp, (It is developed simultaneously, and at some stages, it will have more core functionality)

The Dapp is built using Nextjs and a couple of helpful tools. It has straightforward and complete functionality.

Main assumption for the dapp:

• it works on Nextjs
• it uses erdjs 11.* without the dapp-core library. it uses backed-side redirections to hide the API endpoint. The only exposed one is /api/multiversx and it is used only by the dapp internally
• it uses the .env file - there is an example in the repo (for all configurations, also for the demo config)
• it uses chakra-ui

How to start it locally:

1. clone or download the repo
2. cd nextjs-dapp-template
3. npm install
4. configure .env.local (you can copy the contents of the .env.example) cp .env.example .env.local
5. npm run dev -> for development
6. npm run build -> npm start for production

Check how to deploy a very similar dapp using the Netlify services: https://www.elven.tools/docs/dapp-deployment.html

Howto

For simplicity, the template uses the main index page with demo components built using the core building blocks. Below you will find the list of most essential utilities, hooks, and components with examples that are actual code from the template. You can search them in the code to better understand how they work.

There are much more hooks and tools, but most of them are already used in the ones listed below.

The code samples are not ready to copy and paste. Please search for them in the code.

useNetworkSync()

The hook is responsible for synchronizing the network on each refresh. It should be used in the root component. Here is the _app.tsx.

Why not the context wrapper? Because context wrappers with auth state data checks will break Next ASO.

This way, you can check the auth state in chosen places. You are not forced to do this constantly for the whole document tree.

import { useNetworkSync } from '../hooks/auth/useNetworkSync';

const NextJSDappTemplate = ({ Component, pageProps }: AppProps) => {
  useNetworkSync();
  return (
    <ChakraProvider theme={theme}>
      <Component {...pageProps} />
    </ChakraProvider>
  );
};

LoginModalButton

The component provides the Connect button with the modal, which will contain another three buttons for four different authentication possibilities (Maiar Mobile App, Maiar Defi Wallet - browser extension, Elrond Web Wallet). You should be able to use it in any place on the website.

import { LoginModalButton } from '../tools/LoginModalButton';

<LoginModalButton />;

useLogin

It is the main hook for logging in. It is used in the LoginComponent in the LoginModalButton. The hook is one for all auth providers and can take the auth token as an argument. It can be by any string. Based on this, the auth signature will be generated. This is required when you verify the user account on the backend side. The dapp doesn't use it by default, but you can still pass it.

const { login, isLoggedIn, error, walletConnectUri, getHWAccounts } = useLogin({
  token: 'some_hash_here',
});

Authenticated

The component is used as a small wrapper where we need to be in the authenticated context, for example, for all transactions.

It can display the spinner and also the fallback React element.

Important Do not wrap it in big sections of the code. Its purpose is to be used multiple times on as small blocks as possible.

<Authenticated
  spinnerCentered
  fallback={
    <>
      <Text fontWeight="bold" fontSize="2xl" textAlign="center" mt={8}>
        Connect your wallet!
      </Text>
      <Flex mt={4} justifyContent="center">
        <LoginModalButton />
      </Flex>
    </>
  }
>
  <Box>Do something here in the auth context...</Box>
</Authenticated>

useTransaction()

The hook provides all that is required for triggering transactions. useTransaction can also take a callback function as an argument.

const { pending, triggerTx, transaction, error } = useTransaction({ cb });

const handleSendTx = useCallback(() => {
  const demoMessage = 'Transaction demo!';
  triggerTx({
    address: process.env.NEXT_PUBLIC_EGLD_TRANSFER_ADDRESS,
    gasLimit: 50000 + 1500 * demoMessage.length,
    data: new TransactionPayload(demoMessage),
    value: process.env.NEXT_PUBLIC_EGLD_TRANSFER_AMOUNT,
  });
}, [triggerTx]);

useScTransaction()

The hook provides all that is required for triggering smart contract transactions. useScTransaction can also take a callback function as an argument.

const { pending, triggerTx, transaction, error } = useScTransaction({ cb });

const handleSendTx = useCallback(() => {
  triggerTx({
    smartContractAddress: process.env.NEXT_PUBLIC_MINT_SMART_CONTRACT_ADDRESS,
    func: process.env.NEXT_PUBLIC_MINT_FUNCTION_NAME,
    gasLimit: 14000000,
    args: [new U32Value(1)],
    value: process.env.NEXT_PUBLIC_MINT_PAYMENT_PER_TOKEN,
  });
}, [triggerTx]);

useScQuery()

The hook uses useSWR under the hood and can be triggered on a component mount or remotely on some action. It has two different states for the pending action. For initial load and on revalidate. It also takes one of three return data types: 'number', 'string', 'boolean'. For now, it assumes that you know what data type will be returned by a smart contract. Later it will get more advanced functionality.

const {
  data: queryResult,
  fetch, // you can always trigger the query manually if 'autoInit' is set to false
  isLoading, // pending state for initial load
  isValidating, // pending state for each revalidation of the data, for example using the mutate
  error,
} = useScQuery<number>({
  type: SCQueryType.NUMBER, // can be NUMBER, STRING, BOOLEAN or COMPLEX
  payload: {
    scAddress: process.env.NEXT_PUBLIC_MINT_SMART_CONTRACT_ADDRESS,
    funcName: process.env.NEXT_PUBLIC_QUERY_FUNCTION_NAME,
    args: [], // arguments for the query in hex format, you can use erdjs for that, for example: args: [ new Address('erd1....').hex() ] etc. It will be also simplified in the future.
  },
  autoInit: false, // you can enable or disable the trigger of the query on the component mount
  abiJSON: yourImportedAbiJSONObject // required for SCQueryType.COMPLEX type
});

Example with SCQueryType.COMPLEX. This type uses /vm-values/query, ABI and ResultParser. The ABI JSON contents are required here. You can copy abi.json and import it in the same place you use useScQuery. Put the abi JSON file wherever you like in the codebase. I chose the config directory. See the example below:

import { TypedOutcomeBundle } from '@elrondnetwork/erdjs';
import abiJSON from '../config/abi.json';

const { data } = useScQuery<TypedOutcomeBundle>({
  type: SCQueryType.COMPLEX,
  payload: {
    scAddress: 'erd1qqq...',
    funcName: 'yourScFunction',
    args: [], // args in hex format, use erdjs for conversion, see above
  },
  autoInit: true,
  abiJSON,
});

The data here will be a TypedOutcomeBundle. Which is:

interface TypedOutcomeBundle {
  returnCode: ReturnCode;
  returnMessage: string;
  values: TypedValue[];
  firstValue?: TypedValue;
  secondValue?: TypedValue;
  thirdValue?: TypedValue;
  lastValue?: TypedValue;
}

You can then process the data. For example data.firstValue.valueOf() or data.firstValue.toString() if applicable. The returned type can be further processed using erdjs.

useLoggingIn()

The hook will provide information about the authentication flow state. It will tell if the user is already logged in or is logging in.

const { isLoggingIn, error, isLoggedIn } = useLoggingIn();

useAccount()

The hook will provide information about the user's account data state. The data: address, nonce, balance.

const { address, nonce, balance } = useAccount();

useLoginInfo()

The hook will provide information about the user's auth data state. The data: loginMethod, expires, loginToken, signature. Login token and signature won't always be there. It depends if you'll use the token. Check Elven Tools Dapp backend integration article for more info.

const { loginMethod, expires, loginToken, signature } = useLoginInfo();

useApiCall()

The hook provides a convenient way of doing custom API calls unrelated to transactions or smart contract queries. By default, it will use MultiversX API endpoint. But it can be any type of API, not only MultiversX API. In that case, you would need to pass the { baseEndpoint: "https://some-api.com" } in options

const { data, isLoading, isValidating, fetch, error } = useApiCall<Token[]>({
  url: `/accounts/<some_erd_address_here>/tokens`, // can be any API endpoint without the host, because it is already handled internally
  autoInit: true, // similar to useScQuery
  type: 'get', // can be get, post, delete, put
  payload: {},
  options: {}
});

You can pass the response type. Returned object is the same as in useScQuery The hook uses swr and native fetch under the hood.

Working with the API

The API endpoint is proxied on the backend side. The only public API endpoint is /api/multiversx. This is useful when you don't want to show the API endpoint because, for example, you use the paid ones. Also, there is an option to block the /api/multiversx endpoint to be used only within the Dapp, even previewing it in the browser won't be possible.

You can use API_ALLOWED_DAPP_HOST in the .env file to enable /api/multiversx restrictions. If you don't want to restrict it, you can remove that variable.

In the middleware.ts, you'll find the logic for the API restrictions. And in the next.config.js, you'll find the configuration for rewrites of the API.

In this demo, the Dapp uses a public API endpoint, so it isn't essential, but it is beneficial when you need to use paid 3rd party service.

Read more about it here: https://www.elven.tools/docs/dapp-api-proxy.html

Working with the .env and config files

There is an env.example file that you can copy and rename into .env.local to run the app locally. You would need to configure these variables for your production-ready dapp.

Here are all variables:

# =============================================
# Public variables (exposed on the frontend)
# =============================================

# MultiversX chain (can be devnet, testnet, mainnet)
NEXT_PUBLIC_MULTIVERSX_CHAIN = devnet

# This is the masked/proxied public API endpoint
# only current instance of the Dapp can use it if only API_ALLOWED_DAPP_HOST is set
NEXT_PUBLIC_MULTIVERSX_API = /api/multiversx

# This is basically the main domain of your dapp
NEXT_PUBLIC_DAPP_HOST = http://localhost:3000

# =============================================
# Private variables (used on the backend)
# =============================================

# Your main MultiversX API can be a custom one. There won't be a possibility
# to reveal this endpoint, it will be masked by NEXT_PUBLIC_MULTIVERSX_API
MULTIVERSX_CUSTOM_API = https://devnet-api.elrond.com

# Only this host will be allowed to consume the API (optional)
# It will work only inside the Dapp, no one will be able to use the endpoint, even in browser
# When removed the API will be available for testing through browser, Postman etc.
API_ALLOWED_DAPP_HOST = http://localhost:3000

# =============================================
# Public variables for the the demo only
# =============================================

# The wallet address used for the demo EGLD transaction on the devnet
NEXT_PUBLIC_EGLD_TRANSFER_ADDRESS = erd17a4wydhhd6t3hhssvcp9g23ppn7lgkk4g2tww3eqzx4mlq95dukss0g50f

# The smart contract address used for minting the NFT token (as example deployed Elven Tools Smart Contract)
NEXT_PUBLIC_MINT_SMART_CONTRACT_ADDRESS = erd1qqqqqqqqqqqqqpgq5za2pty2tlfqhj20z9qmrrpjmyt6advcgtkscm7xep

# The function/endpoint name for minting on the smart contract
NEXT_PUBLIC_MINT_FUNCTION_NAME = mint

# The function/view name for getting the total tokens left to be mint on smart contract
NEXT_PUBLIC_QUERY_FUNCTION_NAME = getTotalTokensLeft

# The payment per one NFT token, defined on smart contract (0.01 EGLD)
NEXT_PUBLIC_MINT_PAYMENT_PER_TOKEN = 0.01

# The amount of EGLD to send in the demo transfer (0.001 EGLD)
NEXT_PUBLIC_EGLD_TRANSFER_AMOUNT = 0.001

All variables which start with NEXT_PUBLIC_ will be readable on the frontend side of the dapp. So please don't use them for any secret keys and data. If you need something to be available only on the backend side, don't use the NEXT_PUBLIC_ prefix.

You can set up the chain type here. Use NEXT_PUBLIC_MULTIVERSX_CHAIN to set devnet, testnet or mainnet.

Each hosting provider will have a different way of doing that. We will take a look at how Netlify is doing that below.

Deployment

For deployment, we recommend the Netlify. Why Netlify? Because it is the simplest way to deploy the Nextjs app for free. Of course, the most recommended is the Vercel which you could also try.

As for Netlify, the only what you need to do there is to go to the settings and configure from which repository the app should be deployed. Check out how: Netlify getting started.

Then fill up the env variables. See how here: Netlify env vars setup.

On each repository code push, the Netlify services will redeploy the app.

Read more about it here: https://www.elven.tools/docs/dapp-deployment.html

Here are other deployment solutions: NextJS Deployment.

Missing for now:

• More docs and examples
• More tooling and components
• tests

Other solutions

If you would like to test other templates:

• erd-next-starter
• dapp-template

Dapps using it (send the links if you used it, use issues here on GitHub):

• Elven Tools Dapp
• MultiversX ESDT Faucet Dapp

Compact MultiversX SDK for browsers (no build steps required)

• Elven.js

Contact

• xDevGuild