# Building Subgraph UIs (NextJS/Fetch) [Subgraphs](https://somnia.chain.love) allow developers to efficiently query Somnia blockchain data using GraphQL, making it easy to index and retrieve real-time blockchain activity. In this tutorial, you’ll learn how to: * Fetch blockchain data from a Subgraph API * Fix CORS errors using a NextJS API route * Display token transfers in a real-time UI By the end of this guide, you'll have a fully functional UI that fetches and displays token transfers from Somnia’s Subgraph API. ## Prerequisites * Basic knowledge of React & Next.js. * A deployed Subgraph API on Somnia ([or use an existing one](https://somnia.chain.love/graph)). * Account on see [guide](/developer/building-dapps/data-indexing-and-querying/protofire-subgraph.md). ## Create a NextJS Project Start by creating a new Next.js app. ```bash npx create-next-app@latest somnia-subgraph-ui cd somnia-subgraph-ui ``` Then, install required dependencies. ```bash npm install thirdweb react-query graphql ``` ## Define the Subgraph API in Environment Variables Create a .env.local file in the root folder. ``` NEXT_PUBLIC_SUBGRAPH_URL=https://proxy.somnia.chain.love/subgraphs/name/somnia-testnet/test-mytoken NEXT_PUBLIC_SUBGRAPH_CLIENT_ID=YOUR_CLIENT_ID ``` {% hint style="info" %} 💡 Note: Restart your development server after modifying .env.local: {% endhint %} ```bash npm run dev ``` ## Create a NextJS API Route for the Subgraph Since the Somnia Subgraph API has CORS restrictions, we’ll use a NextJS API route to act as a proxy. Inside the app directory create the folder paths **`api/proxy`** and add a file **`route.ts`** Update the **`route.ts`** file with the following code: ```typescript import { NextResponse } from "next/server"; const SUBGRAPH_URL = process.env.NEXT_PUBLIC_SUBGRAPH_URL as string; const CLIENT_ID = process.env.NEXT_PUBLIC_SUBGRAPH_CLIENT_ID as string; export async function POST(req: Request) { try { const body = await req.json(); const response = await fetch(SUBGRAPH_URL, { method: "POST", headers: { "Content-Type": "application/json", "Client-ID": CLIENT_ID, // ✅ Pass the Subgraph Client ID }, body: JSON.stringify(body), }); const data = await response.json(); return NextResponse.json(data); } catch (error) { console.error("Proxy Error:", error); return NextResponse.json({ error: "Failed to fetch from Subgraph" }, { status: 500 }); } } ``` This code allows your frontend to make requests without triggering CORS errors. ## Fetch and Display Token Transfers in the UI Now that we have the API set up, let’s build a React component that: * Sends the GraphQL query using fetch() * Stores the fetched data using useState() * Displays the token transfers in a simple UI To fetch the latest 10 token transfers, we’ll use this GraphQL query: ```graphql { transfers(first: 10, orderBy: blockTimestamp, orderDirection: desc) { id from to value blockTimestamp transactionHash } } ``` This code fetches the last 10 transfers (first: 10) and orders them by timestamp (latest first). It retrieves wallet addresses (from, to) and the amount transferred (value) and includes the transaction hash (used to generate an explorer link). ## Fetch and Display Data in a React Component Now, let’s integrate the query into our NextJS frontend. Create a folder **`components`** and add a file **`TokenTransfer.ts`** We use **`useState()`** to store transfer data and **`useEffect()`** to fetch it when the component loads. ```typescript "use client"; import { useEffect, useState } from "react"; export default function TokenTransfers() { // Store transfers in state const [transfers, setTransfers] = useState([]); // Track loading state const [loading, setLoading] = useState(true); Next, we fetch the token transfer data when the component loads. useEffect(() => { async function fetchTransfers() { setLoading(true); // Show loading state const query = ` { transfers(first: 10, orderBy: blockTimestamp, orderDirection: desc) { id from to value blockTimestamp transactionHash } } `; const response = await fetch("/api/proxy", { method: "POST", headers: { "Content-Type": "application/json" }, body: JSON.stringify({ query }), }); const { data } = await response.json(); setTransfers(data.transfers || []); // Store results in state setLoading(false); // Hide loading state } fetchTransfers(); }, []); ``` Once data is fetched, we render it inside the UI. ```typescript return (

Latest Token Transfers

{loading ? (

Loading transfers...

) : (
    {transfers.map((transfer) => (

  • From: {transfer.from}

    To: {transfer.to}

    Value: {parseFloat(transfer.value) / 1e18} STT

    TX:{" "} View Transaction

    • ))}
)}
); } ``` The UI shows a loading message while data is being fetched. When data is ready, it displays the latest 10 token transfers. It formats transaction values (value / 1e18) to show the correct STT amount and provides a link to view each transaction on Somnia Explorer. ## Add the Component to the NextJS Page Update the page.tsx file: ```typescript "use client"; import TokenTransfers from "../components/TokenTransfers"; export default function Home() { return (

Welcome to MyToken Dashboard

); } ``` Restart the development server: ``` npm run dev ```
Now your NextJS UI dynamically fetches and displays token transfers from Somnia’s Subgraph! 🔥
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