fix: prevents child-parents

packages/plugin-nested-docs/demo/src/seed/index.ts

@@ -19,7 +19,7 @@ export const seed = async (payload: Payload) => {
     },
   })
 
-  const {id: childID} = await payload.create({
+  const { id: childID } = await payload.create({
     collection: 'pages',
     data: {
       title: 'Child page',
@@ -36,4 +36,12 @@ export const seed = async (payload: Payload) => {
       parent: childID
     },
   })
+
+  await payload.create({
+    collection: 'pages',
+    data: {
+      title: 'Sister page',
+      slug: 'sister-page',
+    },
+  })
 }

packages/plugin-nested-docs/src/fields/parent.ts

@@ -6,7 +6,10 @@ const createParentField = (relationTo: string, overrides?: Partial<RelationshipF
   relationTo,
   type: 'relationship',
   maxDepth: 1,
-  filterOptions: ({id}) => ({id: {not_equals: id}}),
+  filterOptions: ({ id }) => ({
+    id: { not_equals: id },
+    'breadcrumbs.doc': { not_in: [id] },
+  }),
   admin: {
     position: 'sidebar',
     ...overrides?.admin || {},