fix(graphql): population of joins that target relationship fields that have relationTo as an array (#12289)

Fixes population of joins that target relationship fields that have
`relationTo` as an array, for example:
```ts
// Posts collection
{
  name: 'polymorphic',
  type: 'relationship',
  relationTo: ['categories', 'users'],
},
// Categories collection
{
  name: 'polymorphic',
  type: 'join',
  collection: 'posts',
  on: 'polymorphic',
}
```

Thanks @jaycetde for the integration test
https://github.com/payloadcms/payload/pull/12278!

---------

Co-authored-by: Jayce Pulsipher <jpulsipher@nav.com>

packages/graphql/src/schema/buildObjectType.ts

@@ -11,6 +11,7 @@ export type ObjectTypeConfig = {
 
 type Args = {
   baseFields?: ObjectTypeConfig
+  collectionSlug?: string
   config: SanitizedConfig
   fields: Field[]
   forceNullable?: boolean
@@ -23,6 +24,7 @@ type Args = {
 export function buildObjectType({
   name,
   baseFields = {},
+  collectionSlug,
   config,
   fields,
   forceNullable,
@@ -43,6 +45,7 @@ export function buildObjectType({
         return {
           ...objectTypeConfig,
           ...fieldSchema({
+            collectionSlug,
             config,
             field,
             forceNullable,

packages/graphql/src/schema/fieldToSchemaMap.ts

@@ -8,6 +8,7 @@ import type {
   DateField,
   EmailField,
   Field,
+  FlattenedJoinField,
   GraphQLInfo,
   GroupField,
   JoinField,
@@ -68,6 +69,7 @@ function formattedNameResolver({
 }
 
 type SharedArgs = {
+  collectionSlug?: string
   config: SanitizedConfig
   forceNullable?: boolean
   graphqlResult: GraphQLInfo
@@ -340,7 +342,7 @@ export const fieldToSchemaMap: FieldToSchemaMap = {
       },
     }
   },
-  join: ({ field, graphqlResult, objectTypeConfig, parentName }) => {
+  join: ({ collectionSlug, field, graphqlResult, objectTypeConfig, parentName }) => {
     const joinName = combineParentName(parentName, toWords(field.name, true))
 
     const joinType = {
@@ -385,9 +387,23 @@ export const fieldToSchemaMap: FieldToSchemaMap = {
 
         const draft = Boolean(args.draft ?? context.req.query?.draft)
 
-        const fullWhere = combineQueries(where, {
+        const targetField = (field as FlattenedJoinField).targetField
+
+        const fullWhere = combineQueries(
+          where,
+          Array.isArray(targetField.relationTo)
+            ? {
+                [field.on]: {
+                  equals: {
+                    relationTo: collectionSlug,
+                    value: parent._id ?? parent.id,
+                  },
+                },
+              }
+            : {
                 [field.on]: { equals: parent._id ?? parent.id },
-        })
+              },
+        )
 
         if (Array.isArray(collection)) {
           throw new Error('GraphQL with array of join.field.collection is not implemented')

packages/graphql/src/schema/fieldToWhereInputSchemaMap.ts

@@ -29,6 +29,7 @@ import { recursivelyBuildNestedPaths } from './recursivelyBuildNestedPaths.js'
 import { withOperators } from './withOperators.js'
 
 type Args = {
+  collectionSlug?: string
   nestedFieldName?: string
   parentName: string
 }

packages/graphql/src/schema/initCollections.ts

@@ -111,6 +111,7 @@ export function initCollections({ config, graphqlResult }: InitCollectionsGraphQ
     collection.graphQL.type = buildObjectType({
       name: singularName,
       baseFields,
+      collectionSlug: collectionConfig.slug,
       config,
       fields,
       forceNullable: forceNullableObjectType,
@@ -339,6 +340,7 @@ export function initCollections({ config, graphqlResult }: InitCollectionsGraphQ
 
       collection.graphQL.versionType = buildObjectType({
         name: `${singularName}Version`,
+        collectionSlug: collectionConfig.slug,
         config,
         fields: versionCollectionFields,
         forceNullable: forceNullableObjectType,

test/joins/int.spec.ts

@@ -940,6 +940,94 @@ describe('Joins Field', () => {
       )
     })
 
+    it('should have simple paginate with page for joins polymorphic', async () => {
+      let queryWithLimit = `query {
+    Categories(where: {
+            name: { equals: "paginate example" }
+          }) {
+          docs {
+            polymorphic(
+              sort: "createdAt",
+              limit: 2
+            ) {
+              docs {
+                title
+              }
+              hasNextPage
+            }
+          }
+        }
+      }`
+      let pageWithLimit = await restClient
+        .GRAPHQL_POST({ body: JSON.stringify({ query: queryWithLimit }) })
+        .then((res) => res.json())
+
+      const queryUnlimited = `query {
+        Categories(
+          where: {
+            name: { equals: "paginate example" }
+          }
+        ) {
+          docs {
+            polymorphic(
+              sort: "createdAt",
+              limit: 0
+            ) {
+              docs {
+                title
+                createdAt
+              }
+              hasNextPage
+            }
+          }
+        }
+      }`
+
+      const unlimited = await restClient
+        .GRAPHQL_POST({ body: JSON.stringify({ query: queryUnlimited }) })
+        .then((res) => res.json())
+
+      expect(pageWithLimit.data.Categories.docs[0].polymorphic.docs).toHaveLength(2)
+      expect(pageWithLimit.data.Categories.docs[0].polymorphic.docs[0].id).toStrictEqual(
+        unlimited.data.Categories.docs[0].polymorphic.docs[0].id,
+      )
+      expect(pageWithLimit.data.Categories.docs[0].polymorphic.docs[1].id).toStrictEqual(
+        unlimited.data.Categories.docs[0].polymorphic.docs[1].id,
+      )
+
+      expect(pageWithLimit.data.Categories.docs[0].polymorphic.hasNextPage).toStrictEqual(true)
+
+      queryWithLimit = `query {
+        Categories(where: {
+                name: { equals: "paginate example" }
+              }) {
+              docs {
+                polymorphic(
+                  sort: "createdAt",
+                  limit: 2,
+                  page: 2,
+                ) {
+                  docs {
+                    title
+                  }
+                  hasNextPage
+                }
+              }
+            }
+          }`
+
+      pageWithLimit = await restClient
+        .GRAPHQL_POST({ body: JSON.stringify({ query: queryWithLimit }) })
+        .then((res) => res.json())
+
+      expect(pageWithLimit.data.Categories.docs[0].polymorphic.docs[0].id).toStrictEqual(
+        unlimited.data.Categories.docs[0].polymorphic.docs[2].id,
+      )
+      expect(pageWithLimit.data.Categories.docs[0].polymorphic.docs[1].id).toStrictEqual(
+        unlimited.data.Categories.docs[0].polymorphic.docs[3].id,
+      )
+    })
+
     it('should populate joins with hasMany when on both sides documents are in draft', async () => {
       const category = await payload.create({
         collection: 'categories-versions',