feat: generate types for joins (#9054)

### What?
Generates types for `joins` property.
Example from our `joins` test, keys are type-safe:
<img width="708" alt="image"
src="https://github.com/user-attachments/assets/f1fbbb9d-7c39-49a2-8aa2-a4793ae4ad7e">

Output in `payload-types.ts`:
```ts
 collectionsJoins: {
    categories: {
      relatedPosts: 'posts';
      hasManyPosts: 'posts';
      hasManyPostsLocalized: 'posts';
      'group.relatedPosts': 'posts';
      'group.camelCasePosts': 'posts';
      filtered: 'posts';
      singulars: 'singular';
    };
  };
```
Additionally, we include type information about on which collection the
join is, it will help when we have types generation for `where` and
`sort`.

### Why?
It provides a better DX as you don't need to memoize your keys.

### How?
Modifies `configToJSONSchema` to generate the json schema for
`collectionsJoins`, uses that type within `JoinQuery`

packages/payload/src/collections/operations/local/find.ts

@@ -33,7 +33,7 @@ export type Options<TSlug extends CollectionSlug, TSelect extends SelectType> =
   draft?: boolean
   fallbackLocale?: TypedLocale
   includeLockStatus?: boolean
-  joins?: JoinQuery
+  joins?: JoinQuery<TSlug>
   limit?: number
   locale?: 'all' | TypedLocale
   overrideAccess?: boolean

packages/payload/src/collections/operations/local/findByID.ts

@@ -37,7 +37,7 @@ export type Options<
   fallbackLocale?: TypedLocale
   id: number | string
   includeLockStatus?: boolean
-  joins?: JoinQuery
+  joins?: JoinQuery<TSlug>
   locale?: 'all' | TypedLocale
   overrideAccess?: boolean
   populate?: PopulateType

packages/payload/src/index.ts

@@ -97,6 +97,12 @@ export interface GeneratedTypes {
       }
     }
   }
+
+  collectionsJoinsUntyped: {
+    [slug: string]: {
+      [schemaPath: string]: CollectionSlug
+    }
+  }
   collectionsSelectUntyped: {
     [slug: string]: SelectType
   }
@@ -141,6 +147,12 @@ type ResolveCollectionSelectType<T> = 'collectionsSelect' extends keyof T
   ? T['collectionsSelect']
   : // @ts-expect-error
     T['collectionsSelectUntyped']
+
+type ResolveCollectionJoinsType<T> = 'collectionsJoins' extends keyof T
+  ? T['collectionsJoins']
+  : // @ts-expect-error
+    T['collectionsJoinsUntyped']
+
 type ResolveGlobalType<T> = 'globals' extends keyof T
   ? T['globals']
   : // @ts-expect-error
@@ -155,6 +167,9 @@ type ResolveGlobalSelectType<T> = 'globalsSelect' extends keyof T
 export type TypedCollection = ResolveCollectionType<GeneratedTypes>
 
 export type TypedCollectionSelect = ResolveCollectionSelectType<GeneratedTypes>
+
+export type TypedCollectionJoins = ResolveCollectionJoinsType<GeneratedTypes>
+
 export type TypedGlobal = ResolveGlobalType<GeneratedTypes>
 
 export type TypedGlobalSelect = ResolveGlobalSelectType<GeneratedTypes>

packages/payload/src/types/index.ts

@@ -13,6 +13,7 @@ import type {
   DataFromGlobalSlug,
   GlobalSlug,
   RequestContext,
+  TypedCollectionJoins,
   TypedCollectionSelect,
   TypedLocale,
   TypedUser,
@@ -123,17 +124,20 @@ export type Sort = Array<string> | string
 /**
  * Applies pagination for join fields for including collection relationships
  */
-export type JoinQuery =
-  | {
-      [schemaPath: string]:
-        | {
-            limit?: number
-            sort?: string
-            where?: Where
-          }
+export type JoinQuery<TSlug extends CollectionSlug = string> =
+  TypedCollectionJoins[TSlug] extends Record<string, string>
+    ?
         | false
-    }
-  | false
+        | Partial<{
+            [K in keyof TypedCollectionJoins[TSlug]]:
+              | {
+                  limit?: number
+                  sort?: string
+                  where?: Where
+                }
+              | false
+          }>
+    : never
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export type Document = any

packages/payload/src/utilities/configToJSONSchema.ts

@@ -93,6 +93,43 @@ function generateEntitySelectSchemas(
   }
 }
 
+function generateCollectionJoinsSchemas(collections: SanitizedCollectionConfig[]): JSONSchema4 {
+  const properties = [...collections].reduce<Record<string, JSONSchema4>>(
+    (acc, { slug, joins }) => {
+      const schema = {
+        type: 'object',
+        additionalProperties: false,
+        properties: {},
+        required: [],
+      } satisfies JSONSchema4
+
+      for (const collectionSlug in joins) {
+        for (const join of joins[collectionSlug]) {
+          schema.properties[join.schemaPath] = {
+            type: 'string',
+            enum: [collectionSlug],
+          }
+          schema.required.push(join.schemaPath)
+        }
+      }
+
+      if (Object.keys(schema.properties).length > 0) {
+        acc[slug] = schema
+      }
+
+      return acc
+    },
+    {},
+  )
+
+  return {
+    type: 'object',
+    additionalProperties: false,
+    properties,
+    required: Object.keys(properties),
+  }
+}
+
 function generateLocaleEntitySchemas(localization: SanitizedConfig['localization']): JSONSchema4 {
   if (localization && 'locales' in localization && localization?.locales) {
     const localesFromConfig = localization?.locales
@@ -989,6 +1026,7 @@ export function configToJSONSchema(
     properties: {
       auth: generateAuthOperationSchemas(config.collections),
       collections: generateEntitySchemas(config.collections || []),
+      collectionsJoins: generateCollectionJoinsSchemas(config.collections || []),
       collectionsSelect: generateEntitySelectSchemas(config.collections || []),
       db: generateDbEntitySchema(config),
       globals: generateEntitySchemas(config.globals || []),
@@ -1001,6 +1039,7 @@ export function configToJSONSchema(
       'locale',
       'collections',
       'collectionsSelect',
+      'collectionsJoins',
       'globalsSelect',
       'globals',
       'auth',

test/joins/payload-types.ts

@@ -26,7 +26,30 @@ export interface Config {
     'payload-preferences': PayloadPreference;
     'payload-migrations': PayloadMigration;
   };
-  collectionsSelect?: {
+  collectionsJoins: {
+    categories: {
+      relatedPosts: 'posts';
+      hasManyPosts: 'posts';
+      hasManyPostsLocalized: 'posts';
+      'group.relatedPosts': 'posts';
+      'group.camelCasePosts': 'posts';
+      filtered: 'posts';
+      singulars: 'singular';
+    };
+    uploads: {
+      relatedPosts: 'posts';
+    };
+    'categories-versions': {
+      relatedVersions: 'versions';
+    };
+    'localized-categories': {
+      relatedPosts: 'localized-posts';
+    };
+    'restricted-categories': {
+      restrictedPosts: 'posts';
+    };
+  };
+  collectionsSelect: {
     posts: PostsSelect<false> | PostsSelect<true>;
     categories: CategoriesSelect<false> | CategoriesSelect<true>;
     uploads: UploadsSelect<false> | UploadsSelect<true>;
@@ -46,7 +69,7 @@ export interface Config {
     defaultIDType: string;
   };
   globals: {};
-  globalsSelect?: {};
+  globalsSelect: {};
   locale: 'en' | 'es';
   user: User & {
     collection: 'users';

test/select/payload-types.ts

@@ -21,6 +21,7 @@ export interface Config {
     'payload-preferences': PayloadPreference;
     'payload-migrations': PayloadMigration;
   };
+  collectionsJoins: {};
   collectionsSelect: {
     posts: PostsSelect<false> | PostsSelect<true>;
     'localized-posts': LocalizedPostsSelect<false> | LocalizedPostsSelect<true>;