Add useGetAggregateFromServerQuery hook

packages/react/src/firestore/index.ts

@@ -8,5 +8,5 @@
 export { useDocumentQuery } from "./useDocumentQuery";
 // useDocumentsQuery <-- Name? useQuery? Bit generic.
 // useGetCountFromServerQuery
-// useGetAggregateFromServerQuery
+export { useGetAggregateFromServerQuery } from "./useGetAggregateFromServerQuery";
 // useNamedQuery

packages/react/src/firestore/useGetAggregateFromServerQuery.test.tsx

@@ -0,0 +1,156 @@
+import React, { type ReactNode } from "react";
+import { describe, expect, test, beforeEach } from "vitest";
+import { useGetAggregateFromServerQuery } from "./useGetAggregateFromServerQuery";
+import { renderHook, waitFor } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import {
+  collection,
+  addDoc,
+  query,
+  where,
+  sum,
+  average,
+  count,
+} from "firebase/firestore";
+
+import {
+  expectFirestoreError,
+  firestore,
+  wipeFirestore,
+} from "~/testing-utils";
+
+const queryClient = new QueryClient({
+  defaultOptions: {
+    queries: {
+      retry: false,
+    },
+  },
+});
+
+const wrapper = ({ children }: { children: ReactNode }) => (
+  <QueryClientProvider client={queryClient}>{children}</QueryClientProvider>
+);
+
+describe("useGetAggregateFromServerQuery", () => {
+  beforeEach(async () => await wipeFirestore());
+
+  test("returns correct count for empty collection", async () => {
+    const collectionRef = collection(firestore, "tests");
+
+    const { result } = renderHook(
+      () =>
+        useGetAggregateFromServerQuery(collectionRef, {
+          queryKey: ["aggregate", "empty"],
+          firestore: { aggregateSpec: { count: count() } },
+        }),
+      { wrapper }
+    );
+
+    await waitFor(() => expect(result.current.isSuccess).toBe(true));
+
+    expect(result.current.data?.count).toBe(0);
+  });
+
+  test("returns correct aggregate values for non-empty collection", async () => {
+    const collectionRef = collection(firestore, "tests");
+
+    await addDoc(collectionRef, { value: 10 });
+    await addDoc(collectionRef, { value: 20 });
+    await addDoc(collectionRef, { value: 30 });
+
+    const { result } = renderHook(
+      () =>
+        useGetAggregateFromServerQuery(collectionRef, {
+          queryKey: ["aggregate", "non-empty"],
+          firestore: {
+            aggregateSpec: {
+              count: count(),
+              sum: sum("value"),
+              avg: average("value"),
+            },
+          },
+        }),
+      { wrapper }
+    );
+
+    await waitFor(() => expect(result.current.isSuccess).toBe(true));
+
+    expect(result.current.data?.count).toBe(3);
+    expect(result.current.data?.sum).toBe(60);
+    expect(result.current.data?.avg).toBe(20);
+  });
+
+  test("handles complex queries", async () => {
+    const collectionRef = collection(firestore, "tests");
+
+    await addDoc(collectionRef, { category: "A", value: 10 });
+    await addDoc(collectionRef, { category: "B", value: 20 });
+    await addDoc(collectionRef, { category: "A", value: 30 });
+    await addDoc(collectionRef, { category: "C", value: 40 });
+
+    const complexQuery = query(collectionRef, where("category", "==", "A"));
+
+    const { result } = renderHook(
+      () =>
+        useGetAggregateFromServerQuery(complexQuery, {
+          queryKey: ["aggregate", "complex"],
+          firestore: {
+            aggregateSpec: {
+              count: count(),
+              sum: sum("value"),
+              avg: average("value"),
+            },
+          },
+        }),
+      { wrapper }
+    );
+
+    await waitFor(() => expect(result.current.isSuccess).toBe(true));
+
+    expect(result.current.data?.count).toBe(2);
+    expect(result.current.data?.sum).toBe(40);
+    expect(result.current.data?.avg).toBe(20);
+  });
+
+  test("handles restricted collections appropriately", async () => {
+    const restrictedCollectionRef = collection(
+      firestore,
+      "restrictedCollection"
+    );
+
+    const { result } = renderHook(
+      () =>
+        useGetAggregateFromServerQuery(restrictedCollectionRef, {
+          queryKey: ["aggregate", "restricted"],
+          firestore: { aggregateSpec: { count: count() } },
+        }),
+      { wrapper }
+    );
+
+    await waitFor(() => expect(result.current.isError).toBe(true));
+
+    expectFirestoreError(result.current.error, "permission-denied");
+  });
+
+  test("returns pending state initially", async () => {
+    const collectionRef = collection(firestore, "tests");
+
+    await addDoc(collectionRef, { value: 10 });
+
+    const { result } = renderHook(
+      () =>
+        useGetAggregateFromServerQuery(collectionRef, {
+          queryKey: ["aggregate", "pending"],
+          firestore: { aggregateSpec: { count: count() } },
+        }),
+      { wrapper }
+    );
+
+    // Initially isPending should be true
+    expect(result.current.isPending).toBe(true);
+
+    await waitFor(() => expect(result.current.isSuccess).toBe(true));
+
+    expect(result.current.data?.count).toBe(1);
+  });
+});

packages/react/src/firestore/useGetAggregateFromServerQuery.ts

@@ -0,0 +1,41 @@
+import { useQuery, type UseQueryOptions } from "@tanstack/react-query";
+import {
+  type Query,
+  type FirestoreError,
+  getAggregateFromServer,
+  type AggregateSpec,
+  type AggregateField,
+} from "firebase/firestore";
+
+type FirestoreUseQueryOptions<TData = unknown, TError = Error> = Omit<
+  UseQueryOptions<TData, TError>,
+  "queryFn"
+> & {
+  firestore: {
+    aggregateSpec: AggregateSpec;
+  };
+};
+
+type AggregateResult<T extends AggregateSpec> = {
+  [K in keyof T]: AggregateField<T[K]> extends AggregateField<infer R>
+    ? R
+    : never;
+};
+
+export function useGetAggregateFromServerQuery<T extends AggregateSpec>(
+  query: Query,
+  options: FirestoreUseQueryOptions<AggregateResult<T>, FirestoreError>
+) {
+  const { firestore, ...queryOptions } = options;
+
+  return useQuery<AggregateResult<T>, FirestoreError>({
+    ...queryOptions,
+    queryFn: async () => {
+      const snapshot = await getAggregateFromServer(
+        query,
+        firestore.aggregateSpec
+      );
+      return snapshot.data() as AggregateResult<T>;
+    },
+  });
+}