fix(db-postgres): query unset relation (#4862)

test/relationships/config.ts

@@ -43,6 +43,7 @@ export const chainedRelSlug = 'chained'
 export const customIdSlug = 'custom-id'
 export const customIdNumberSlug = 'custom-id-number'
 export const polymorphicRelationshipsSlug = 'polymorphic-relationships'
+export const treeSlug = 'tree'
 
 export default buildConfigWithDefaults({
   collections: [
@@ -244,6 +245,20 @@ export default buildConfigWithDefaults({
         },
       ],
     },
+    {
+      slug: treeSlug,
+      fields: [
+        {
+          name: 'text',
+          type: 'text',
+        },
+        {
+          name: 'parent',
+          type: 'relationship',
+          relationTo: 'tree',
+        },
+      ],
+    },
   ],
   onInit: async (payload) => {
     await payload.create({
@@ -337,5 +352,20 @@ export default buildConfigWithDefaults({
         filteredRelation: filteredRelation.id,
       },
     })
+
+    const root = await payload.create({
+      collection: 'tree',
+      data: {
+        text: 'root',
+      },
+    })
+
+    await payload.create({
+      collection: 'tree',
+      data: {
+        text: 'sub',
+        parent: root.id,
+      },
+    })
   },
 })

test/relationships/int.spec.ts

@@ -22,6 +22,7 @@ import config, {
   defaultAccessRelSlug,
   relationSlug,
   slug,
+  treeSlug,
 } from './config'
 
 let apiUrl
@@ -554,6 +555,64 @@ describe('Relationships', () => {
         expect(stanleyNeverMadeMovies.movies).toHaveLength(0)
       })
     })
+
+    describe('Hierarchy', () => {
+      it('finds 1 root item with equals', async () => {
+        const {
+          docs: [item],
+          totalDocs: count,
+        } = await payload.find({
+          collection: treeSlug,
+          where: {
+            parent: { equals: null },
+          },
+        })
+        expect(count).toBe(1)
+        expect(item.text).toBe('root')
+      })
+
+      it('finds 1 root item with exists', async () => {
+        const {
+          docs: [item],
+          totalDocs: count,
+        } = await payload.find({
+          collection: treeSlug,
+          where: {
+            parent: { exists: false },
+          },
+        })
+        expect(count).toBe(1)
+        expect(item.text).toBe('root')
+      })
+
+      it('finds 1 sub item with equals', async () => {
+        const {
+          docs: [item],
+          totalDocs: count,
+        } = await payload.find({
+          collection: treeSlug,
+          where: {
+            parent: { not_equals: null },
+          },
+        })
+        expect(count).toBe(1)
+        expect(item.text).toBe('sub')
+      })
+
+      it('finds 1 sub item with exists', async () => {
+        const {
+          docs: [item],
+          totalDocs: count,
+        } = await payload.find({
+          collection: treeSlug,
+          where: {
+            parent: { exists: true },
+          },
+        })
+        expect(count).toBe(1)
+        expect(item.text).toBe('sub')
+      })
+    })
   })
 
   describe('Creating', () => {