Feat: Fetch sighting details from the backend

AGENTS.md

@@ -5,7 +5,7 @@
 - **Name:** UFOund it
 - **What it is:** UFOund it, is a webapp that displays UFO sightings.
 - **Dataset:** [NUFORC UFO Sightings (Kaggle)](https://www.kaggle.com/datasets/NUFORC/ufo-sightings), CSV, approx 80,000 reports, approx 15mb.
-- **Current state:** The backend is an Apollo Server with `sightings`, `sighting` and `createSighting`, backed by MySQL on the VM. The search page fetches sightings through Apollo Client, with search, sort and "load more" pagination done in the database. The detail page still looks sightings up in the hand-written mock data in `frontend/src/data/`. A temporary footer shows whether the backend is reachable.
+- **Current state:** The backend is an Apollo Server with `sightings`, `sighting` and `createSighting`, backed by MySQL on the VM. The search and detail pages fetch sightings through Apollo Client, with search, sort and "load more" pagination done in the database. A temporary footer shows whether the backend is reachable.
 - **Course context:** NTNU IT2810 project. Must be reproducible, accessible and sustainable.
 
 ## Tech stack
@@ -69,7 +69,7 @@ frontend/
     hooks/        Custom hooks (debounce, sighting search, single sighting)
     utils/        Pure helpers (formatting)
     types/        Shared TypeScript types
-    data/         Mock sightings, still used by the detail page and as test fixtures
+    tests/        Vitest tests and the mock sightings they use as fixtures
     graphql/      Apollo Client setup and pagination cache rules (client.ts), queries.ts and mutations.ts
 backend/          Node + TypeScript GraphQL server (Apollo Server 5)
   src/

frontend/src/graphql/queries.ts

@@ -71,3 +71,30 @@ export const SIGHTINGS_QUERY: TypedDocumentNode<
     }
   }
 `
+
+interface SightingQueryData {
+  /** Null if no sighting has the id. */
+  sighting: UfoSighting | null
+}
+
+/** A single sighting by id, for the detail page. */
+export const SIGHTING_QUERY: TypedDocumentNode<
+  SightingQueryData,
+  { id: string }
+> = gql`
+  query Sighting($id: ID!) {
+    sighting(id: $id) {
+      id
+      datetime
+      city
+      state
+      country
+      shape
+      durationSeconds
+      comments
+      datePosted
+      latitude
+      longitude
+    }
+  }
+`

frontend/src/hooks/use-sighting.ts

@@ -1,11 +1,20 @@
-import type { UfoSighting } from '../types/ufo-sighting'
-import { useSightings } from './use-sightings'
+import { useQuery } from '@apollo/client/react'
+import { SIGHTING_QUERY } from '../graphql/queries'
 
 /**
- * Looks up a single sighting by id. Wrapped in a hook so the detail page
- * won't need to change when this becomes a GraphQL query.
+ * Fetches one sighting. `sighting` is null once the load has finished and
+ * the backend has no sighting with that id, which is not an `error`.
  */
-export function useSighting(id: string | undefined): UfoSighting | undefined {
-  const sightings = useSightings()
-  return sightings.find((sighting) => sighting.id === id)
+export function useSighting(id: string) {
+  const { data, loading, error, refetch } = useQuery(SIGHTING_QUERY, {
+    variables: { id },
+  })
+
+  // A failed refetch is shown through `error`, so the rejected promise
+  // needs no handling of its own.
+  const retry = () => {
+    refetch().catch(() => {})
+  }
+
+  return { sighting: data?.sighting ?? null, loading, error, retry }
 }

frontend/src/pages/SightingDetailPage.tsx

@@ -27,11 +27,15 @@ function getFromSearch(state: unknown): string {
 }
 
 function SightingDetailPage() {
-  const { id } = useParams()
-  const sighting = useSighting(id)
+  const { id = '' } = useParams()
+  const { sighting, loading, error, retry } = useSighting(id)
   const location = useLocation()
   const backTo = { pathname: '/', search: getFromSearch(location.state) }
-  const title = sighting ? formatLocation(sighting) : 'Sighting not found'
+
+  let title = 'Sighting not found'
+  if (sighting) title = formatLocation(sighting)
+  else if (error) title = 'Could not load sighting'
+  else if (loading) title = 'Loading sighting…'
 
   // Route changes keep the list's scroll position, which would open the
   // detail page scrolled past its heading.
@@ -58,7 +62,16 @@ function SightingDetailPage() {
       <div className="sighting-detail">
         {backLink}
         <h1>{title}</h1>
-        <p>There is no sighting with id “{id}”.</p>
+        {error ? (
+          <div role="alert">
+            <p>Check your connection and try again.</p>
+            <button type="button" onClick={retry}>
+              Try again
+            </button>
+          </div>
+        ) : (
+          !loading && <p>There is no sighting with id “{id}”.</p>
+        )}
       </div>
     )
   }

frontend/src/pages/SubmitSightingPage.tsx

@@ -2,10 +2,8 @@ import { CombinedGraphQLErrors } from '@apollo/client'
 import { useMutation } from '@apollo/client/react'
 import { useState, type FormEvent } from 'react'
 import { Link } from 'react-router'
-import { addSighting } from '../data/sighting-store'
 import {
   CREATE_SIGHTING_MUTATION,
-  type CreatedSighting,
   type SightingFieldError,
 } from '../graphql/mutations'
 import LocationPicker from '../components/LocationPicker'
@@ -91,24 +89,6 @@ function serverFieldErrors(error: unknown): FormErrors | null {
   return errors
 }
 
-// The API allows nulls for imported rows, but a submitted sighting always
-// has every field except state, so the fallbacks are only for type safety.
-function toUfoSighting(created: CreatedSighting) {
-  return {
-    id: created.id,
-    datetime: created.datetime ?? '',
-    city: created.city ?? '',
-    state: created.state ?? '',
-    country: created.country ?? '',
-    shape: created.shape ?? '',
-    durationSeconds: created.durationSeconds ?? 0,
-    comments: created.comments ?? '',
-    datePosted: created.datePosted ?? '',
-    latitude: created.latitude ?? 0,
-    longitude: created.longitude ?? 0,
-  }
-}
-
 function SubmitSightingPage() {
   const [values, setValues] = useState(initialValues)
   const [errors, setErrors] = useState<FormErrors>({})
@@ -152,7 +132,6 @@ function SubmitSightingPage() {
         },
       })
       if (!data) throw new Error('createSighting returned no data')
-      addSighting(toUfoSighting(data.createSighting))
       setSubmittedId(data.createSighting.id)
     } catch (error) {
       const fieldErrors = serverFieldErrors(error)

frontend/src/tests/SearchPage.test.tsx

@@ -4,7 +4,7 @@ import { fireEvent, render, screen, waitFor } from '@testing-library/react'
 import { MemoryRouter } from 'react-router'
 import { of, throwError } from 'rxjs'
 import { describe, expect, it, vi } from 'vitest'
-import { mockSightings } from '../data/mock-sightings'
+import { mockSightings } from './mock-sightings'
 import { createCache } from '../graphql/client'
 import type { SightingsQueryVariables } from '../graphql/queries'
 import SearchPage from '../pages/SearchPage'

frontend/src/tests/SightingDetailPage.test.tsx

@@ -1,7 +1,13 @@
-import { render, screen } from '@testing-library/react'
+import {
+  MockedProvider,
+  type MockedProviderProps,
+} from '@apollo/client/testing/react'
+import { fireEvent, render, screen } from '@testing-library/react'
 import { MemoryRouter, Route, Routes } from 'react-router'
 import { afterEach, describe, expect, it, vi } from 'vitest'
+import { SIGHTING_QUERY } from '../graphql/queries'
 import SightingDetailPage from '../pages/SightingDetailPage'
+import { mockSightings } from './mock-sightings'
 
 vi.mock('../components/SightingMap', () => ({
   default: ({
@@ -19,13 +25,26 @@ vi.mock('../components/SightingMap', () => ({
   ),
 }))
 
-function renderDetailPage(path: string, state?: unknown) {
+const found = {
+  request: { query: SIGHTING_QUERY, variables: { id: '1' } },
+  result: {
+    data: { sighting: { __typename: 'Sighting', ...mockSightings[0] } },
+  },
+}
+
+function renderDetailPage(
+  path: string,
+  mocks: MockedProviderProps['mocks'],
+  state?: unknown,
+) {
   return render(
-    <MemoryRouter initialEntries={[{ pathname: path, state }]}>
-      <Routes>
-        <Route path="/sightings/:id" element={<SightingDetailPage />} />
-      </Routes>
-    </MemoryRouter>,
+    <MockedProvider mocks={mocks}>
+      <MemoryRouter initialEntries={[{ pathname: path, state }]}>
+        <Routes>
+          <Route path="/sightings/:id" element={<SightingDetailPage />} />
+        </Routes>
+      </MemoryRouter>
+    </MockedProvider>,
   )
 }
 
@@ -34,12 +53,15 @@ describe('SightingDetailPage', () => {
     vi.restoreAllMocks()
   })
 
-  it('renders sighting details and preserves the originating search link', () => {
+  it('renders sighting details and preserves the originating search link', async () => {
     vi.spyOn(window, 'scrollTo').mockImplementation(() => {})
-    renderDetailPage('/sightings/1', { fromSearch: '?q=San+Marcos' })
+    renderDetailPage('/sightings/1', [found], { fromSearch: '?q=San+Marcos' })
 
     expect(
-      screen.getByRole('heading', { name: 'San Marcos, TX, US' }),
+      screen.getByRole('heading', { name: 'Loading sighting…' }),
+    ).toBeInTheDocument()
+    expect(
+      await screen.findByRole('heading', { name: 'San Marcos, TX, US' }),
     ).toBeInTheDocument()
     expect(screen.getByText('45 min')).toBeInTheDocument()
     expect(screen.getByText(/This event took place/)).toBeInTheDocument()
@@ -54,12 +76,17 @@ describe('SightingDetailPage', () => {
     expect(document.title).toBe('San Marcos, TX, US · UFOund it')
   })
 
-  it('handles missing sightings and links back to the unfiltered list', () => {
+  it('handles unknown ids and links back to the unfiltered list', async () => {
     vi.spyOn(window, 'scrollTo').mockImplementation(() => {})
-    renderDetailPage('/sightings/missing')
+    renderDetailPage('/sightings/missing', [
+      {
+        request: { query: SIGHTING_QUERY, variables: { id: 'missing' } },
+        result: { data: { sighting: null } },
+      },
+    ])
 
     expect(
-      screen.getByRole('heading', { name: 'Sighting not found' }),
+      await screen.findByRole('heading', { name: 'Sighting not found' }),
     ).toBeInTheDocument()
     expect(
       screen.getByText('There is no sighting with id “missing”.'),
@@ -70,4 +97,25 @@ describe('SightingDetailPage', () => {
     expect(screen.queryByTestId('detail-map')).not.toBeInTheDocument()
     expect(document.title).toBe('Sighting not found · UFOund it')
   })
+
+  it('shows an error and lets the user retry', async () => {
+    vi.spyOn(window, 'scrollTo').mockImplementation(() => {})
+    renderDetailPage('/sightings/1', [
+      { ...found, error: new Error('Network down') },
+      found,
+    ])
+
+    expect(await screen.findByRole('alert')).toHaveTextContent(
+      'Check your connection',
+    )
+    expect(
+      screen.getByRole('heading', { name: 'Could not load sighting' }),
+    ).toBeInTheDocument()
+
+    fireEvent.click(screen.getByRole('button', { name: 'Try again' }))
+
+    expect(
+      await screen.findByRole('heading', { name: 'San Marcos, TX, US' }),
+    ).toBeInTheDocument()
+  })
 })

frontend/src/tests/SightingList.test.tsx

@@ -3,7 +3,7 @@ import type { ComponentProps } from 'react'
 import { MemoryRouter } from 'react-router'
 import { describe, expect, it, vi } from 'vitest'
 import SightingList from '../components/SightingList'
-import { mockSightings } from '../data/mock-sightings'
+import { mockSightings } from './mock-sightings'
 
 vi.mock('../components/SightingMap', () => ({
   default: () => <div data-testid="sighting-map" />,

frontend/src/tests/SightingMap.test.tsx

@@ -2,7 +2,7 @@ import type { ReactNode } from 'react'
 import { render, screen } from '@testing-library/react'
 import { describe, expect, it } from 'vitest'
 import SightingMap from '../components/SightingMap'
-import { mockSightings } from '../data/mock-sightings'
+import { mockSightings } from './mock-sightings'
 
 type MapProps = {
   children: ReactNode

frontend/src/tests/SubmitSightingPage.test.tsx

@@ -6,7 +6,6 @@ import { GraphQLError } from 'graphql'
 import { fireEvent, render, screen } from '@testing-library/react'
 import { MemoryRouter } from 'react-router'
 import { describe, expect, it, vi } from 'vitest'
-import { getSightings } from '../data/sighting-store'
 import { CREATE_SIGHTING_MUTATION } from '../graphql/mutations'
 import SubmitSightingPage from '../pages/SubmitSightingPage'
 
@@ -86,7 +85,6 @@ describe('SubmitSightingPage', () => {
     expect(
       screen.getByRole('link', { name: 'View your sighting' }),
     ).toHaveAttribute('href', '/sightings/90001')
-    expect(getSightings()[0]).toMatchObject({ id: '90001', state: '' })
   })
 
   it('shows field errors returned by the server next to the field', async () => {

frontend/src/tests/hooks.test.tsx

@@ -1,8 +1,6 @@
 import { act, renderHook } from '@testing-library/react'
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import { mockSightings } from '../data/mock-sightings'
 import { useDebouncedValue } from '../hooks/use-debounced-value'
-import { useSighting } from '../hooks/use-sighting'
 
 describe('sighting hooks', () => {
   afterEach(() => {
@@ -23,17 +21,4 @@ describe('sighting hooks', () => {
     act(() => vi.advanceTimersByTime(1))
     expect(result.current).toBe('second')
   })
-
-  it('looks up an existing sighting and returns undefined for an unknown id', () => {
-    const { result, rerender } = renderHook(({ id }) => useSighting(id), {
-      initialProps: { id: mockSightings[0].id as string | undefined },
-    })
-    expect(result.current).toEqual(mockSightings[0])
-
-    rerender({ id: 'not-a-sighting' })
-    expect(result.current).toBeUndefined()
-
-    rerender({ id: undefined })
-    expect(result.current).toBeUndefined()
-  })
 })

frontend/src/data/mock-sightings.ts → frontend/src/tests/mock-sightings.ts

@@ -1,10 +1,6 @@
 import type { UfoSighting } from '../types/ufo-sighting'
 
-/**
- * Hand-written sample sightings. The search page now reads from GraphQL,
- * but the detail page still looks sightings up here, and tests use them as
- * fixtures. Remove from the app once the detail page uses GraphQL.
- */
+/** Hand-written sample sightings, used as fixtures by the tests. */
 export const mockSightings: UfoSighting[] = [
   {
     id: '1',