From 73631313f153203ef638bad452a9b19423237523 Mon Sep 17 00:00:00 2001
From: Vitaliy Bravikov <vitaliyb@stud.ntnu.no>
Date: Mon, 19 Oct 2026 09:54:17 +0200
Subject: [PATCH] Sorting is performed on backend queries, and additional check
 is performed on NULL values.

---
 backend/src/db/sightings.ts   |  4 +--
 backend/src/schema.db.test.ts | 51 +++++++++++++++++++++++++++++++++--
 backend/src/schema.test.ts    | 11 ++++----
 3 files changed, 57 insertions(+), 9 deletions(-)

diff --git a/backend/src/db/sightings.ts b/backend/src/db/sightings.ts
index 79e71e8..12fbe78 100644
--- a/backend/src/db/sightings.ts
+++ b/backend/src/db/sightings.ts
@@ -41,8 +41,8 @@ const SELECT = `
 const ORDER_BY = {
   DATE_DESC: 's.SIGHTING_DATETIME DESC, s.UFO_SIGHTING_ID DESC',
   DATE_ASC: 's.SIGHTING_DATETIME ASC, s.UFO_SIGHTING_ID ASC',
-  CITY_ASC: 'l.CITY ASC, s.UFO_SIGHTING_ID ASC',
-  SHAPE_ASC: 'sh.NAME ASC, s.UFO_SIGHTING_ID ASC',
+  CITY_ASC: "NULLIF(l.CITY, '') IS NULL, l.CITY ASC, s.UFO_SIGHTING_ID ASC",
+  SHAPE_ASC: "NULLIF(sh.NAME, '') IS NULL, sh.NAME ASC, s.UFO_SIGHTING_ID ASC",
 }
 
 // MySQL gives "2005-01-01 00:30:00"; the API uses ISO 8601 without timezone.
diff --git a/backend/src/schema.db.test.ts b/backend/src/schema.db.test.ts
index bbaf46a..92aff27 100644
--- a/backend/src/schema.db.test.ts
+++ b/backend/src/schema.db.test.ts
@@ -11,7 +11,12 @@ import { resolvers, typeDefs } from './schema.ts'
 //  npx tsx --env-file=.env --test src/schema.db.test.ts
 const hasDatabase = Boolean(process.env.DB_NAME)
 
-type Node = { id: string; datetime: string | null; shape: string | null }
+type Node = {
+  id: string
+  datetime: string | null
+  city: string | null
+  shape: string | null
+}
 type Page = {
   totalCount: number
   pageInfo: { hasNextPage: boolean; endCursor: string | null }
@@ -29,7 +34,7 @@ async function sightings(variables: Record<string, unknown>): Promise<Page> {
                   first: $first, after: $after) {
           totalCount
           pageInfo { hasNextPage endCursor }
-          edges { node { id datetime shape } }
+          edges { node { id datetime city shape } }
         }
       }`,
     variables,
@@ -98,6 +103,48 @@ describe('sightings against the real database', { skip: !hasDatabase }, () => {
     })
   }
 
+  for (const [sort, field] of [
+    ['CITY_ASC', 'city'],
+    ['SHAPE_ASC', 'shape'],
+  ] as const) {
+    it(`puts missing values last and returns every sighting once (${sort})`, async () => {
+      const seen = new Set<string>()
+      let missingSeen = false
+      let after: string | null = null
+      let page: Page
+
+      do {
+        page = await sightings({ sort, first: 100, after })
+        assert.ok(page.edges.length > 0, 'the dataset should contain sightings')
+        if (after === null) {
+          assert.ok(page.edges[0].node[field], 'real names should come first')
+        }
+
+        for (const { node } of page.edges) {
+          assert.ok(!seen.has(node.id), `duplicate sighting ${node.id}`)
+          seen.add(node.id)
+          if (node[field] === null || node[field] === '') {
+            missingSeen = true
+          } else {
+            assert.equal(
+              missingSeen,
+              false,
+              'a real name followed a missing value',
+            )
+          }
+        }
+
+        after = page.pageInfo.endCursor
+      } while (page.pageInfo.hasNextPage)
+
+      assert.equal(
+        seen.size,
+        page.totalCount,
+        'every sighting should be returned',
+      )
+    })
+  }
+
   it('sorts by date across page boundaries', async () => {
     const dates: string[] = []
     let after: string | null = null
diff --git a/backend/src/schema.test.ts b/backend/src/schema.test.ts
index be8611c..1ae2214 100644
--- a/backend/src/schema.test.ts
+++ b/backend/src/schema.test.ts
@@ -88,10 +88,11 @@ describe('sightings search', () => {
 
 describe('sightings sort', () => {
   const orders = {
-    DATE_DESC: 's.SIGHTING_DATETIME DESC',
-    DATE_ASC: 's.SIGHTING_DATETIME ASC',
-    CITY_ASC: 'l.CITY ASC',
-    SHAPE_ASC: 'sh.NAME ASC',
+    DATE_DESC: 's.SIGHTING_DATETIME DESC, s.UFO_SIGHTING_ID DESC',
+    DATE_ASC: 's.SIGHTING_DATETIME ASC, s.UFO_SIGHTING_ID ASC',
+    CITY_ASC: "NULLIF(l.CITY, '') IS NULL, l.CITY ASC, s.UFO_SIGHTING_ID ASC",
+    SHAPE_ASC:
+      "NULLIF(sh.NAME, '') IS NULL, sh.NAME ASC, s.UFO_SIGHTING_ID ASC",
   }
 
   for (const [sort, clause] of Object.entries(orders)) {
@@ -99,7 +100,7 @@ describe('sightings sort', () => {
       fakeDatabase([])
       await run(SIGHTINGS, { sort })
 
-      assert.ok(listCall().sql.includes(`ORDER BY ${clause}`))
+      assert.ok(listCall().sql.includes(`ORDER BY ${clause} LIMIT ? OFFSET ?`))
     })
   }