feat(react): multichain query hooks

.changeset/itchy-carrots-think.md

@@ -0,0 +1,5 @@
+---
+"@reactive-dot/react": minor
+---
+
+Added concurrent multi-chain query capability hooks.

apps/docs/react/guides/multichain.md

@@ -117,6 +117,28 @@ function Component() {
 }
 ```
 
+## Multi-chain query
+
+You can query multiple chains concurrently by passing an array of query options to the [`useLazyLoadQuery`](/api/react/function/useLazyLoadQuery) hook. This prevents suspense waterfalls and improves performance.
+
+```tsx
+import { useLazyLoadQuery } from "@reactive-dot/react";
+
+function Component() {
+  const [totalNominationPoolsValue, assets] = useLazyLoadQuery([
+    {
+      chainId: "polkadot",
+      query: (builder) =>
+        builder.readStorage("NominationPools", "TotalValueLocked", []),
+    },
+    {
+      chainId: "polkadot_asset_hub",
+      query: (builder) => builder.readStorageEntries("Assets", "Asset", []),
+    },
+  ]);
+}
+```
+
 ## Chain narrowing
 
 By default, ReactiveDOT merges type definitions from all the chains in the config. For instance, if your DApp is set up to work with Polkadot, Kusama, and Westend, the following code will fail because the Bounties pallet is available only on Polkadot and Kusama, not on Westend:

examples/react/.papi/descriptors/package.json

@@ -1,5 +1,5 @@
 {
-  "version": "0.1.0-autogenerated.14047238154392085370",
+  "version": "0.1.0-autogenerated.5420105234347264657",
   "name": "@polkadot-api/descriptors",
   "files": [
     "dist"

examples/react/.papi/polkadot-api.json

@@ -18,9 +18,19 @@
       "chain": "ksmcc3",
       "metadata": ".papi/metadata/kusama.scale"
     },
+    "kusama_asset_hub": {
+      "chain": "ksmcc3_asset_hub",
+      "metadata": ".papi/metadata/kusama_asset_hub.scale",
+      "genesis": "0x48239ef607d7928874027a43a67689209727dfb3d3dc5e5b03a39bdc2eda771a"
+    },
     "westend": {
       "chain": "westend2",
       "metadata": ".papi/metadata/westend.scale"
+    },
+    "westend_asset_hub": {
+      "chain": "westend2_asset_hub",
+      "metadata": ".papi/metadata/westend_asset_hub.scale",
+      "genesis": "0x67f9723393ef76214df0118c34bbbd3dbebc8ed46a10973a8c969d48fe7598c9"
     }
   }
-}
+}

examples/react/src/app.tsx

@@ -1,4 +1,5 @@
 import { config } from "./config";
+import { MultichainQuery } from "./multichain-query";
 import { Mutation } from "./mutation";
 import { Query } from "./query";
 import { WalletConnection } from "./wallet-connection";
@@ -73,6 +74,7 @@ function Example({ chainName }: ExampleProps) {
         <Suspense fallback={<h2>Loading {chainName}...</h2>}>
           <h2>{chainName}</h2>
           <Query />
+          <MultichainQuery />
           <Mutation />
         </Suspense>
       </ErrorBoundary>

examples/react/src/config.ts

@@ -1,9 +1,11 @@
 import {
   kusama,
+  kusama_asset_hub,
   polkadot,
   polkadot_asset_hub,
   polkadot_people,
   westend,
+  westend_asset_hub,
 } from "@polkadot-api/descriptors";
 import { defineConfig } from "@reactive-dot/core";
 import { createLightClientProvider } from "@reactive-dot/core/providers/light-client.js";
@@ -15,6 +17,10 @@ const lightClientProvider = createLightClientProvider();
 
 const polkadotProvider = lightClientProvider.addRelayChain({ id: "polkadot" });
 
+const kusamaProvider = lightClientProvider.addRelayChain({ id: "kusama" });
+
+const westendProvider = lightClientProvider.addRelayChain({ id: "westend" });
+
 export const config = defineConfig({
   chains: {
     polkadot: {
@@ -31,11 +37,19 @@ export const config = defineConfig({
     },
     kusama: {
       descriptor: kusama,
-      provider: lightClientProvider.addRelayChain({ id: "kusama" }),
+      provider: kusamaProvider,
+    },
+    kusama_asset_hub: {
+      descriptor: kusama_asset_hub,
+      provider: kusamaProvider.addParachain({ id: "kusama_asset_hub" }),
     },
     westend: {
       descriptor: westend,
-      provider: lightClientProvider.addRelayChain({ id: "westend" }),
+      provider: westendProvider,
+    },
+    westend_asset_hub: {
+      descriptor: westend_asset_hub,
+      provider: westendProvider.addParachain({ id: "westend_asset_hub" }),
     },
   },
   targetChains: ["polkadot", "kusama", "westend"],

examples/react/src/multichain-query.tsx

@@ -0,0 +1,40 @@
+import { useChainId, useLazyLoadQuery } from "@reactive-dot/react";
+import { useMemo } from "react";
+
+export function MultichainQuery() {
+  const chainId = useChainId();
+
+  const [parachains, assetHubParaId] = useLazyLoadQuery([
+    {
+      chainId: undefined,
+      query: (builder) => builder.readStorage("Paras", "Parachains", []),
+    },
+    {
+      chainId: useMemo(() => {
+        switch (chainId) {
+          case "polkadot":
+          case "polkadot_asset_hub":
+          case "polkadot_people":
+            return "polkadot_asset_hub";
+          case "kusama":
+          case "kusama_asset_hub":
+            return "kusama_asset_hub";
+          case "westend":
+          case "westend_asset_hub":
+            return "westend_asset_hub";
+        }
+      }, [chainId]),
+      query: (builder) =>
+        builder.readStorage("ParachainInfo", "ParachainId", []),
+    },
+  ]);
+
+  return (
+    <dl>
+      <dt>Parachain IDs</dt>
+      <dd>{parachains.map((id) => id.toLocaleString()).join()}</dd>
+      <dt>Asset Hub ID</dt>
+      <dd>{assetHubParaId.toLocaleString()}</dd>
+    </dl>
+  );
+}

packages/react/src/hooks/use-query-loader.ts

@@ -36,7 +36,14 @@ export function useQueryLoader() {
       ) => {
         const query = builder(new Query());
 
-        void get(queryPayloadAtom(config, options?.chainId ?? chainId, query));
+        void get(
+          queryPayloadAtom(config, [
+            {
+              query,
+              chainId: options?.chainId ?? chainId,
+            },
+          ]),
+        );
       },
     [chainId, config],
   );

packages/react/src/hooks/use-query-options.test.tsx

@@ -0,0 +1,65 @@
+import { ChainIdContext } from "../contexts/chain.js";
+import { useQueryOptions } from "./use-query-options.js";
+import { Query, ReactiveDotError } from "@reactive-dot/core";
+import { renderHook } from "@testing-library/react";
+import { expect, it } from "vitest";
+
+it("throws error when no chainId is provided", () => {
+  const renderFunction = () =>
+    renderHook(() => useQueryOptions((q: Query) => q));
+
+  expect(renderFunction).toThrow(ReactiveDotError);
+  expect(renderFunction).toThrow("No chain ID provided");
+});
+
+it("handles single query with context chainId", () => {
+  const chainId = 1;
+  const wrapper = ({ children }: { children: React.ReactNode }) => (
+    <ChainIdContext value={chainId}>{children}</ChainIdContext>
+  );
+
+  const { result } = renderHook(() => useQueryOptions((q: Query) => q), {
+    wrapper,
+  });
+
+  expect(result.current).toHaveLength(1);
+  expect(result.current[0].chainId).toBe(chainId);
+  expect(result.current[0].query).toBeInstanceOf(Query);
+});
+
+it("handles single query with explicit chainId", () => {
+  const chainId = 1;
+  const { result } = renderHook(() =>
+    useQueryOptions((q: Query) => q, { chainId }),
+  );
+
+  expect(result.current).toHaveLength(1);
+  expect(result.current[0].chainId).toBe(chainId);
+  expect(result.current[0].query).toBeInstanceOf(Query);
+});
+
+it("handles multiple queries with different chainIds", () => {
+  const options = [
+    { chainId: 1, query: (q: Query) => q },
+    { chainId: 2, query: (q: Query) => q },
+  ];
+
+  const { result } = renderHook(() => useQueryOptions(options));
+
+  expect(result.current).toHaveLength(2);
+  expect(result.current[0].chainId).toBe(1);
+  expect(result.current[1].chainId).toBe(2);
+  expect(result.current[0].query).toBeInstanceOf(Query);
+  expect(result.current[1].query).toBeInstanceOf(Query);
+});
+
+it("handles Query instance directly", () => {
+  const chainId = 1;
+  const query = new Query();
+
+  const { result } = renderHook(() => useQueryOptions(query, { chainId }));
+
+  expect(result.current).toHaveLength(1);
+  expect(result.current[0].chainId).toBe(chainId);
+  expect(result.current[0].query).toBe(query);
+});

packages/react/src/hooks/use-query-options.ts

@@ -0,0 +1,78 @@
+import { ChainIdContext } from "../contexts/chain.js";
+import type { QueryArgument, ChainHookOptions } from "./types.js";
+import { type ChainId, Query, ReactiveDotError } from "@reactive-dot/core";
+import { use, useMemo } from "react";
+
+/**
+ * @internal
+ */
+export function useQueryOptions<
+  TChainId extends ChainId | undefined,
+  TQuery extends QueryArgument<TChainId>,
+>(
+  query: TQuery,
+  options?: ChainHookOptions<TChainId>,
+): Array<{
+  chainId: ChainId;
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  query: Query<any, any> | undefined;
+}>;
+/**
+ * @internal
+ */
+export function useQueryOptions<
+  TChainIds extends Array<ChainId | undefined>,
+  const TOptions extends {
+    [P in keyof TChainIds]: ChainHookOptions<TChainIds[P]> & {
+      query: QueryArgument<TChainIds[P]>;
+    };
+  },
+>(
+  options: TOptions & {
+    [P in keyof TChainIds]: ChainHookOptions<TChainIds[P]> & {
+      query: QueryArgument<TChainIds[P]>;
+    };
+  },
+): Array<{
+  chainId: ChainId;
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  query: Query<any, any> | undefined;
+}>;
+/**
+ * @internal
+ */
+export function useQueryOptions(
+  queryOrOptions: // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  | QueryArgument<any>
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    | Array<ChainHookOptions<any> & { query: QueryArgument<any> }>,
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  mayBeOptions?: ChainHookOptions<any>,
+) {
+  const contextChainId = use(ChainIdContext);
+
+  return useMemo(
+    () =>
+      (Array.isArray(queryOrOptions)
+        ? queryOrOptions
+        : [{ query: queryOrOptions, ...mayBeOptions }]
+      ).map((options) => {
+        const chainId = options.chainId ?? contextChainId;
+
+        if (chainId === undefined) {
+          throw new ReactiveDotError("No chain ID provided");
+        }
+
+        return {
+          chainId,
+          query:
+            options.query instanceof Query
+              ? options.query
+              : typeof options.query === "function"
+                ? options.query(new Query([])) || undefined
+                : undefined,
+        };
+      }),
+    [contextChainId, mayBeOptions, queryOrOptions],
+  );
+}