@backchain/api

Server-side helpers for building REST APIs and batched reads on top of the Backchain SDK.

Install

npm install @backchain/api

Quick Start

import express from 'express';
import { backchainMiddleware, setupBackchainRoutes } from '@backchain/api';

const app = express();
app.use(backchainMiddleware({ provider, addresses }));
setupBackchainRoutes(app);
app.listen(3000);

API

Multicall

Batches multiple read calls into a single eth_call using Multicall3 at 0xcA11bde05977b3631167028862bE2a173976CA11.

• new Multicall(provider: Provider): Multicall
• add(target: string, calldata: string): this — queue a call.
• execute(): Promise<MulticallResult[]> — submit all queued calls in one RPC request and return decoded results.
• executeTyped<T>(calls: TypedCall<T>[]): Promise<T[]> — typed variant that decodes results according to provided ABI fragments.

const mc = new Multicall(provider);
mc.add(addresses.BKCToken, iface.encodeFunctionData('totalSupply'));
mc.add(addresses.StakingPool, iface.encodeFunctionData('totalStaked'));
const [supply, staked] = await mc.execute();

backchainMiddleware(options: MiddlewareOptions)

Express middleware that constructs a BackchainContext and attaches it to req.backchain on every request.

• options.provider — ethers.js v6 provider instance.
• options.addresses — contract address map (loaded from deployment-addresses.json).
• options.signerKey? — optional private key for server-side signing.

generateRoutes(modules: ModuleMap): Router

Introspects the provided module map and auto-generates GET routes for every public read method. Routes follow the pattern /:module/:method.

const router = generateRoutes({ swap: new SwapModule(ctx), staking: new StakingModule(ctx) });
app.use('/api', router);
// GET /api/swap/getCurrentPrice
// GET /api/staking/getTotalStaked

setupBackchainRoutes(app: Express, options?: SetupOptions)

Convenience function that calls backchainMiddleware() and generateRoutes() together and mounts all routes under /api (configurable via options.prefix).

Notes

• Multicall3 is available on all major EVM networks at the canonical address.
• backchainMiddleware is stateless; a new BackchainContext is created per-request.
• Generated routes are read-only (GET). Write operations must be implemented manually with a signer.

License

MIT