feat: allow findDistinct on fields nested to relationships and on virtual fields (#14026)

This adds support for using `findDistinct`
https://github.com/payloadcms/payload/pull/13102 on fields:
* Nested to a relationship, for example `category.title`
* Virtual fields that are linked to relationships, for example
`categoryTitle`


```tsx
const Category: CollectionConfig = {
  slug: 'categories',
  fields: [
    {
      name: 'title',
      type: 'text',
    },
  ],
}

const Posts: CollectionConfig = {
  slug: 'posts',
  fields: [
    {
      name: 'category',
      type: 'relationship',
      relationTo: 'categories',
    },
    {
      name: 'categoryTitle',
      type: 'text',
      virtual: 'category.title',
    },
  ],
}

// Supported now
const relationResult = await payload.findDistinct({ collection: 'posts', field: 'category.title' })
// Supported now
const virtualResult = await payload.findDistinct({ collection: 'posts', field: 'categoryTitle' })
```

test/database/getConfig.ts

@@ -126,6 +126,11 @@ export const getConfig: () => Partial<Config> = () => ({
           relationTo: 'categories',
           name: 'category',
         },
+        {
+          type: 'text',
+          name: 'categoryTitle',
+          virtual: 'category.title',
+        },
         {
           type: 'relationship',
           relationTo: 'categories',

test/database/int.spec.ts

@@ -1102,6 +1102,94 @@ describe('database', () => {
     expect(result.values.some((v) => v.categoryPolyMany === null)).toBe(true)
   })
 
+  it('should find distinct values with field nested to a relationship', async () => {
+    await payload.delete({ collection: 'posts', where: {} })
+    await payload.delete({ collection: 'categories', where: {} })
+
+    const category_1 = await payload.create({
+      collection: 'categories',
+      data: { title: 'category_1' },
+    })
+    const category_2 = await payload.create({
+      collection: 'categories',
+      data: { title: 'category_2' },
+    })
+    const category_3 = await payload.create({
+      collection: 'categories',
+      data: { title: 'category_3' },
+    })
+
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_1 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_2 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_2 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_2 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_3 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_3 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_3 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_3 } })
+
+    const res = await payload.findDistinct({
+      collection: 'posts',
+      field: 'category.title',
+    })
+
+    expect(res.values).toEqual([
+      {
+        'category.title': 'category_1',
+      },
+      {
+        'category.title': 'category_2',
+      },
+      {
+        'category.title': 'category_3',
+      },
+    ])
+  })
+
+  it('should find distinct values with virtual field linked to a relationship', async () => {
+    await payload.delete({ collection: 'posts', where: {} })
+    await payload.delete({ collection: 'categories', where: {} })
+
+    const category_1 = await payload.create({
+      collection: 'categories',
+      data: { title: 'category_1' },
+    })
+    const category_2 = await payload.create({
+      collection: 'categories',
+      data: { title: 'category_2' },
+    })
+    const category_3 = await payload.create({
+      collection: 'categories',
+      data: { title: 'category_3' },
+    })
+
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_1 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_2 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_2 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_2 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_3 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_3 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_3 } })
+    await payload.create({ collection: 'posts', data: { title: 'post', category: category_3 } })
+
+    const res = await payload.findDistinct({
+      collection: 'posts',
+      field: 'categoryTitle',
+    })
+
+    expect(res.values).toEqual([
+      {
+        categoryTitle: 'category_1',
+      },
+      {
+        categoryTitle: 'category_2',
+      },
+      {
+        categoryTitle: 'category_3',
+      },
+    ])
+  })
+
   describe('Compound Indexes', () => {
     beforeEach(async () => {
       await payload.delete({ collection: 'compound-indexes', where: {} })

test/database/payload-types.ts

@@ -197,6 +197,7 @@ export interface Post {
   id: string;
   title: string;
   category?: (string | null) | Category;
+  categoryTitle?: string | null;
   categories?: (string | Category)[] | null;
   categoryPoly?: {
     relationTo: 'categories';
@@ -210,22 +211,28 @@ export interface Post {
     | null;
   categoryCustomID?: (number | null) | CategoriesCustomId;
   polymorphicRelations?:
-    | ({
-        relationTo: 'categories';
-        value: string | Category;
-      } | {
-        relationTo: 'simple';
-        value: string | Simple;
-      })[]
+    | (
+        | {
+            relationTo: 'categories';
+            value: string | Category;
+          }
+        | {
+            relationTo: 'simple';
+            value: string | Simple;
+          }
+      )[]
     | null;
   localizedPolymorphicRelations?:
-    | ({
-        relationTo: 'categories';
-        value: string | Category;
-      } | {
-        relationTo: 'simple';
-        value: string | Simple;
-      })[]
+    | (
+        | {
+            relationTo: 'categories';
+            value: string | Category;
+          }
+        | {
+            relationTo: 'simple';
+            value: string | Simple;
+          }
+      )[]
     | null;
   localized?: string | null;
   text?: string | null;
@@ -245,6 +252,23 @@ export interface Post {
         blockType: 'block-third';
       }[]
     | null;
+  testNestedGroup?: {
+    nestedLocalizedPolymorphicRelation?:
+      | (
+          | {
+              relationTo: 'categories';
+              value: string | Category;
+            }
+          | {
+              relationTo: 'simple';
+              value: string | Simple;
+            }
+        )[]
+      | null;
+    nestedLocalizedText?: string | null;
+    nestedText1?: string | null;
+    nestedText2?: string | null;
+  };
   D1?: {
     D2?: {
       D3?: {
@@ -252,20 +276,6 @@ export interface Post {
       };
     };
   };
-  testNestedGroup?: {
-    nestedLocalizedPolymorphicRelation?:
-      | ({
-          relationTo: 'categories';
-          value: string | Category;
-        } | {
-          relationTo: 'simple';
-          value: string | Simple;
-        })[]
-      | null;
-    nestedLocalizedText?: string | null;
-    nestedText1?: string | null;
-    nestedText2?: string | null;
-  };
   hasTransaction?: boolean | null;
   throwAfterChange?: boolean | null;
   arrayWithIDs?:
@@ -868,6 +878,7 @@ export interface CategoriesCustomIdSelect<T extends boolean = true> {
 export interface PostsSelect<T extends boolean = true> {
   title?: T;
   category?: T;
+  categoryTitle?: T;
   categories?: T;
   categoryPoly?: T;
   categoryPolyMany?: T;
@@ -898,6 +909,14 @@ export interface PostsSelect<T extends boolean = true> {
               blockName?: T;
             };
       };
+  testNestedGroup?:
+    | T
+    | {
+        nestedLocalizedPolymorphicRelation?: T;
+        nestedLocalizedText?: T;
+        nestedText1?: T;
+        nestedText2?: T;
+      };
   D1?:
     | T
     | {
@@ -1455,6 +1474,6 @@ export interface Auth {
 
 
 declare module 'payload' {
-  // @ts-ignore
+  // @ts-ignore 
   export interface GeneratedTypes extends Config {}
-}
+}