fix(solid-db): support findOne in useLiveQuery (#1403)

* test(solid-db): add findOne tests for useLiveQuery

Add runtime and type tests for findOne support in solid-db's useLiveQuery.
These tests currently fail, reproducing #1399.

Fixes #1399

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* ci: apply automated fixes

* fix(solid-db): support findOne in useLiveQuery

Update type overloads to use InferResultType<TContext> so findOne queries
return T | undefined instead of Array<T>. Add SingleResult/NonSingleResult
overloads for pre-created collections. Check config.singleResult at runtime
to return the first element instead of the full array.

Fixes #1399

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: add changeset for solid-db findOne fix

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

Author: 3 people

.changeset/fix-solid-db-findone.md

@@ -0,0 +1,9 @@
+---
+'@tanstack/solid-db': patch
+---
+
+fix(solid-db): support findOne in useLiveQuery
+
+`useLiveQuery` with `.findOne()` returned an array instead of a single object. Updated type overloads to use `InferResultType<TContext>` so findOne queries return `T | undefined`, and added a runtime `singleResult` check to return the first element instead of the full array.
+
+Fixes #1399

packages/solid-db/src/useLiveQuery.ts

@@ -17,12 +17,16 @@ import type { Accessor } from 'solid-js'
 import type {
   ChangeMessage,
   Collection,
+  CollectionConfigSingleRowOption,
   CollectionStatus,
   Context,
   GetResult,
+  InferResultType,
   InitialQueryBuilder,
   LiveQueryCollectionConfig,
+  NonSingleResult,
   QueryBuilder,
+  SingleResult,
 } from '@tanstack/db'
 
 /**
@@ -97,12 +101,12 @@ import type {
 // Overload 1: Accept query function that always returns QueryBuilder
 export function useLiveQuery<TContext extends Context>(
   queryFn: (q: InitialQueryBuilder) => QueryBuilder<TContext>,
-): Accessor<Array<GetResult<TContext>>> & {
+): Accessor<InferResultType<TContext>> & {
   /**
    * @deprecated use function result instead
    * query.data -> query()
    */
-  data: Array<GetResult<TContext>>
+  data: InferResultType<TContext>
   state: ReactiveMap<string | number, GetResult<TContext>>
   collection: Collection<GetResult<TContext>, string | number, {}>
   status: CollectionStatus
@@ -118,12 +122,12 @@ export function useLiveQuery<TContext extends Context>(
   queryFn: (
     q: InitialQueryBuilder,
   ) => QueryBuilder<TContext> | undefined | null,
-): Accessor<Array<GetResult<TContext>>> & {
+): Accessor<InferResultType<TContext>> & {
   /**
    * @deprecated use function result instead
    * query.data -> query()
    */
-  data: Array<GetResult<TContext>>
+  data: InferResultType<TContext>
   state: ReactiveMap<string | number, GetResult<TContext>>
   collection: Collection<GetResult<TContext>, string | number, {}> | null
   status: CollectionStatus | `disabled`
@@ -177,12 +181,12 @@ export function useLiveQuery<TContext extends Context>(
 // Overload 2: Accept config object
 export function useLiveQuery<TContext extends Context>(
   config: Accessor<LiveQueryCollectionConfig<TContext>>,
-): Accessor<Array<GetResult<TContext>>> & {
+): Accessor<InferResultType<TContext>> & {
   /**
    * @deprecated use function result instead
    * query.data -> query()
    */
-  data: Array<GetResult<TContext>>
+  data: InferResultType<TContext>
   state: ReactiveMap<string | number, GetResult<TContext>>
   collection: Collection<GetResult<TContext>, string | number, {}>
   status: CollectionStatus
@@ -228,13 +232,15 @@ export function useLiveQuery<TContext extends Context>(
  *  </Switch>
  * )
  */
-// Overload 3: Accept pre-created live query collection
+// Overload 3: Accept pre-created live query collection (non-single result)
 export function useLiveQuery<
   TResult extends object,
   TKey extends string | number,
   TUtils extends Record<string, any>,
 >(
-  liveQueryCollection: Accessor<Collection<TResult, TKey, TUtils>>,
+  liveQueryCollection: Accessor<
+    Collection<TResult, TKey, TUtils> & NonSingleResult
+  >,
 ): Accessor<Array<TResult>> & {
   /**
    * @deprecated use function result instead
@@ -251,6 +257,31 @@ export function useLiveQuery<
   isCleanedUp: boolean
 }
 
+// Overload 3b: Accept pre-created live query collection with singleResult: true
+export function useLiveQuery<
+  TResult extends object,
+  TKey extends string | number,
+  TUtils extends Record<string, any>,
+>(
+  liveQueryCollection: Accessor<
+    Collection<TResult, TKey, TUtils> & SingleResult
+  >,
+): Accessor<TResult | undefined> & {
+  /**
+   * @deprecated use function result instead
+   * query.data -> query()
+   */
+  data: TResult | undefined
+  state: ReactiveMap<TKey, TResult>
+  collection: Collection<TResult, TKey, TUtils> & SingleResult
+  status: CollectionStatus
+  isLoading: boolean
+  isReady: boolean
+  isIdle: boolean
+  isError: boolean
+  isCleanedUp: boolean
+}
+
 // Implementation - use function overloads to infer the actual collection type
 export function useLiveQuery(
   configOrQueryOrCollection: (queryFn?: any) => any,
@@ -393,6 +424,16 @@ export function useLiveQuery(
 
   // We have to remove getters from the resource function so we wrap it
   function getData() {
+    const currentCollection = collection()
+    if (currentCollection) {
+      const config: CollectionConfigSingleRowOption<any, any, any> =
+        currentCollection.config
+      if (config.singleResult) {
+        // Force resource tracking so Suspense works
+        getDataResource()
+        return data[0]
+      }
+    }
     return getDataResource()
   }
 

packages/solid-db/tests/useLiveQuery.test-d.tsx

@@ -0,0 +1,88 @@
+import { describe, expectTypeOf, it } from 'vitest'
+import { renderHook } from '@solidjs/testing-library'
+import { createCollection } from '../../db/src/collection/index'
+import { mockSyncCollectionOptions } from '../../db/tests/utils'
+import { createLiveQueryCollection, eq } from '../../db/src/query/index'
+import { useLiveQuery } from '../src/useLiveQuery'
+import type { OutputWithVirtual } from '../../db/tests/utils'
+import type { SingleResult } from '../../db/src/types'
+
+type Person = {
+  id: string
+  name: string
+  age: number
+  email: string
+  isActive: boolean
+  team: string
+}
+
+describe(`useLiveQuery type assertions`, () => {
+  it(`should type findOne query builder to return a single row`, () => {
+    const collection = createCollection(
+      mockSyncCollectionOptions<Person>({
+        id: `test-persons-2`,
+        getKey: (person: Person) => person.id,
+        initialData: [],
+      }),
+    )
+
+    const rendered = renderHook(() => {
+      return useLiveQuery((q) =>
+        q
+          .from({ collection })
+          .where(({ collection: c }) => eq(c.id, `3`))
+          .findOne(),
+      )
+    })
+
+    expectTypeOf(rendered.result()).toMatchTypeOf<
+      OutputWithVirtual<Person> | undefined
+    >()
+  })
+
+  it(`should type findOne collection using createLiveQueryCollection to return a single row`, () => {
+    const collection = createCollection(
+      mockSyncCollectionOptions<Person>({
+        id: `test-persons-2`,
+        getKey: (person: Person) => person.id,
+        initialData: [],
+      }),
+    )
+
+    const liveQueryCollection = createLiveQueryCollection({
+      query: (q) =>
+        q
+          .from({ collection })
+          .where(({ collection: c }) => eq(c.id, `3`))
+          .findOne(),
+    })
+
+    expectTypeOf(liveQueryCollection).toExtend<SingleResult>()
+
+    const rendered = renderHook(() => {
+      return useLiveQuery(() => liveQueryCollection)
+    })
+
+    expectTypeOf(rendered.result()).toMatchTypeOf<
+      OutputWithVirtual<Person> | undefined
+    >()
+  })
+
+  it(`should type non-findOne queries to return an array`, () => {
+    const collection = createCollection(
+      mockSyncCollectionOptions<Person>({
+        id: `test-persons-2`,
+        getKey: (person: Person) => person.id,
+        initialData: [],
+      }),
+    )
+
+    const rendered = renderHook(() => {
+      return useLiveQuery((q) => q.from({ collection }))
+    })
+
+    expectTypeOf(rendered.result()).toMatchTypeOf<
+      Array<OutputWithVirtual<Person>>
+    >()
+  })
+})

packages/solid-db/tests/useLiveQuery.test.tsx

@@ -2453,4 +2453,138 @@ describe(`Query Collections`, () => {
       expect(finalIds).toEqual([`1`, `2`, `3`, `4`])
     })
   })
+
+  describe(`findOne`, () => {
+    it(`should return a single row with query builder`, async () => {
+      const collection = createCollection(
+        mockSyncCollectionOptions<Person>({
+          id: `test-persons-findone-qb`,
+          getKey: (person: Person) => person.id,
+          initialData: initialPersons,
+        }),
+      )
+
+      const rendered = renderHook(() => {
+        return useLiveQuery((q) =>
+          q
+            .from({ collection })
+            .where(({ collection: c }) => eq(c.id, `3`))
+            .findOne(),
+        )
+      })
+
+      // Wait for collection to sync
+      await waitFor(() => {
+        expect(rendered.result.state.size).toBe(1)
+      })
+
+      expect(rendered.result.state.get(`3`)).toMatchObject({
+        id: `3`,
+        name: `John Smith`,
+      })
+
+      expect(rendered.result()).toMatchObject({
+        id: `3`,
+        name: `John Smith`,
+      })
+    })
+
+    it(`should return a single row with config object`, async () => {
+      const collection = createCollection(
+        mockSyncCollectionOptions<Person>({
+          id: `test-persons-findone-config`,
+          getKey: (person: Person) => person.id,
+          initialData: initialPersons,
+        }),
+      )
+
+      const rendered = renderHook(() => {
+        return useLiveQuery(() => ({
+          query: (q: any) =>
+            q
+              .from({ collection })
+              .where(({ collection: c }: any) => eq(c.id, `3`))
+              .findOne(),
+        }))
+      })
+
+      // Wait for collection to sync
+      await waitFor(() => {
+        expect(rendered.result.state.size).toBe(1)
+      })
+
+      expect(rendered.result.state.get(`3`)).toMatchObject({
+        id: `3`,
+        name: `John Smith`,
+      })
+
+      expect(rendered.result()).toMatchObject({
+        id: `3`,
+        name: `John Smith`,
+      })
+    })
+
+    it(`should return a single row with pre-created collection`, async () => {
+      const collection = createCollection(
+        mockSyncCollectionOptions<Person>({
+          id: `test-persons-findone-collection`,
+          getKey: (person: Person) => person.id,
+          initialData: initialPersons,
+        }),
+      )
+
+      const liveQueryCollection = createLiveQueryCollection({
+        query: (q) =>
+          q
+            .from({ collection })
+            .where(({ collection: c }) => eq(c.id, `3`))
+            .findOne(),
+      })
+
+      const rendered = renderHook(() => {
+        return useLiveQuery(() => liveQueryCollection)
+      })
+
+      // Wait for collection to sync
+      await waitFor(() => {
+        expect(rendered.result.state.size).toBe(1)
+      })
+
+      expect(rendered.result.state.get(`3`)).toMatchObject({
+        id: `3`,
+        name: `John Smith`,
+      })
+
+      expect(rendered.result()).toMatchObject({
+        id: `3`,
+        name: `John Smith`,
+      })
+    })
+
+    it(`should return undefined when findOne matches no rows`, async () => {
+      const collection = createCollection(
+        mockSyncCollectionOptions<Person>({
+          id: `test-persons-findone-empty`,
+          getKey: (person: Person) => person.id,
+          initialData: initialPersons,
+        }),
+      )
+
+      const rendered = renderHook(() => {
+        return useLiveQuery((q) =>
+          q
+            .from({ collection })
+            .where(({ collection: c }) => eq(c.id, `nonexistent`))
+            .findOne(),
+        )
+      })
+
+      // Wait for collection to be ready
+      await waitFor(() => {
+        expect(rendered.result.isReady).toBe(true)
+      })
+
+      expect(rendered.result()).toBeUndefined()
+    })
+  })
 })