fix(db-mongodb): 4x and more level deep relationships querying (#12800)

Fixes https://github.com/payloadcms/payload/issues/12721

test/relationships/config.ts

@@ -254,6 +254,11 @@ export default buildConfigWithDefaults({
           relationTo: 'movies',
           hasMany: true,
         },
+        {
+          name: 'movie',
+          type: 'relationship',
+          relationTo: 'movies',
+        },
         {
           name: 'directors',
           type: 'relationship',

test/relationships/int.spec.ts

@@ -17,7 +17,6 @@ import type {
 } from './payload-types.js'
 
 import { initPayloadInt } from '../helpers/initPayloadInt.js'
-import { isMongoose } from '../helpers/isMongoose.js'
 import {
   chainedRelSlug,
   customIdNumberSlug,
@@ -430,6 +429,33 @@ describe('Relationships', () => {
         expect(result.docs[0].id).toBe(id)
       })
 
+      it('should allow 4x deep querying', async () => {
+        const movie_1 = await payload.create({
+          collection: 'movies',
+          data: { name: 'random_movie_1' },
+        })
+        const director_1 = await payload.create({
+          collection: 'directors',
+          data: { name: 'random_director_1', movie: movie_1.id },
+        })
+        const movie_2 = await payload.create({
+          collection: 'movies',
+          data: { name: 'random_movie_2', director: director_1.id },
+        })
+        const director_2 = await payload.create({
+          collection: 'directors',
+          data: { name: 'random_director_2', movie: movie_2.id },
+        })
+
+        const res = await payload.find({
+          collection: 'directors',
+          where: { 'movie.director.movie.name': { equals: 'random_movie_1' } },
+        })
+
+        expect(res.totalDocs).toBe(1)
+        expect(res.docs[0].id).toBe(director_2.id)
+      })
+
       describe('hasMany relationships', () => {
         it('should retrieve totalDocs correctly with hasMany,', async () => {
           const movie1 = await payload.create({

test/relationships/payload-types.ts

@@ -280,6 +280,7 @@ export interface Director {
   name?: string | null;
   localized?: string | null;
   movies?: (string | Movie)[] | null;
+  movie?: (string | null) | Movie;
   directors?: (string | Director)[] | null;
   updatedAt: string;
   createdAt: string;
@@ -742,6 +743,7 @@ export interface DirectorsSelect<T extends boolean = true> {
   name?: T;
   localized?: T;
   movies?: T;
+  movie?: T;
   directors?: T;
   updatedAt?: T;
   createdAt?: T;