fix: support deeply nested relations (#349)

kettanaito · web-flow · commit 2ad167b0d349 · 2026-03-24T21:16:55.000+01:00
diff --git a/README.md b/README.md
@@ -34,7 +34,7 @@ You start by defining a data _collection_.
 
 ```ts
 import { Collection } from '@msw/data'
-import z from 'zod'
+import { z } from 'zod'
 
 const users = new Collection({
   schema: z.object({
diff --git a/decisions/standard-schema.md b/decisions/standard-schema.md
@@ -4,7 +4,7 @@ I chose to adopt [Standard Schema](https://standardschema.dev/) as the way to de
 
 ```ts
 import { Collection } from '@msw/data'
-import z from 'zod'
+import { z } from 'zod'
 
 const users = new Collection({
   schema: z.object({
diff --git a/src/collection.ts b/src/collection.ts
@@ -535,6 +535,12 @@ export class Collection<Schema extends StandardSchemaV1> {
       descriptor: PropertyDescriptor
     }> = []
 
+    // Track visited records by primary key to detect cycles
+    // in self-referencing relations. Only strip relation values
+    // when revisiting a record (i.e. an actual cycle), not for
+    // all nested records indiscriminately.
+    const visited = new Set<string>()
+
     const sanitize = (
       value: unknown,
       path: Array<string | number | symbol> = [],
@@ -544,7 +550,14 @@ export class Collection<Schema extends StandardSchemaV1> {
       }
 
       if (isObject(value)) {
-        const relations = isRecord(value) ? value[kRelationMap] : undefined
+        const record = isRecord(value) ? value : undefined
+        const isRevisit = record != null && visited.has(record[kPrimaryKey])
+
+        if (record && !isRevisit) {
+          visited.add(record[kPrimaryKey])
+        }
+
+        const relations = record ? record[kRelationMap] : undefined
 
         return Object.fromEntries(
           Reflect.ownKeys(value).map((key) => {
@@ -569,7 +582,10 @@ export class Collection<Schema extends StandardSchemaV1> {
 
             const relation = relations?.get(key)
 
-            if (relation && childValue != null) {
+            // Only strip relation values when revisiting a record
+            // to break self-referencing cycles. Non-circular nested
+            // relations are left intact for proper schema validation.
+            if (isRevisit && relation && childValue != null) {
               propertiesToRestore.push({
                 path: childPath,
                 descriptor: Object.getOwnPropertyDescriptor(value, key)!,
@@ -586,6 +602,7 @@ export class Collection<Schema extends StandardSchemaV1> {
     }
 
     const sanitizedInitialValues = sanitize(initialValues)
+
     return {
       sanitizedInitialValues,
       /**
diff --git a/tests/clear.test.ts b/tests/clear.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({ id: z.number() })
 
diff --git a/tests/count.test.ts b/tests/count.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({
   id: z.number(),
diff --git a/tests/create-derived-property.test.ts b/tests/create-derived-property.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/index.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('derives a value from other values', async () => {
   const users = new Collection({
diff --git a/tests/create-many.test.ts b/tests/create-many.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({
   id: z.number(),
diff --git a/tests/delete-many.test.ts b/tests/delete-many.test.ts
@@ -1,6 +1,6 @@
 import { Collection } from '#/src/collection.js'
 import { Query } from '#/src/query.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({
   id: z.number(),
diff --git a/tests/delete.test.ts b/tests/delete.test.ts
@@ -1,6 +1,6 @@
 import { Collection } from '#/src/collection.js'
 import { Query } from '#/src/query.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({
   id: z.number(),
diff --git a/tests/find-many.test.ts b/tests/find-many.test.ts
@@ -1,5 +1,5 @@
 import { Collection, Query } from '#/src/index.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({
   id: z.number(),
diff --git a/tests/hooks/create.test.ts b/tests/hooks/create.test.ts
@@ -1,6 +1,6 @@
 import { Collection } from '#/src/collection.js'
 import type { HookEventListener } from '#/src/hooks.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('invokes the create hook when a new record is created', async () => {
   const users = new Collection({
diff --git a/tests/hooks/delete.test.ts b/tests/hooks/delete.test.ts
@@ -1,6 +1,6 @@
 import { Collection } from '#/src/collection.js'
 import type { HookEventListener } from '#/src/hooks.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('invokes the delete hook when a record is deleted', async () => {
   const users = new Collection({
diff --git a/tests/hooks/update.test.ts b/tests/hooks/update.test.ts
@@ -1,7 +1,7 @@
 import { Collection } from '#/src/collection.js'
 import type { HookEventListener } from '#/src/hooks.js'
 import { isRecord } from '#/src/utils.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('invokes the update hook for a root property update', async () => {
   const users = new Collection({
diff --git a/tests/nullable.test.ts b/tests/nullable.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('supports null as initial value for nullable properties', async () => {
   const users = new Collection({
diff --git a/tests/pagination-cursor.test.ts b/tests/pagination-cursor.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const userSchema = z.object({
   id: z.number(),
diff --git a/tests/pagination-offset.test.ts b/tests/pagination-offset.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const userSchema = z.object({
   id: z.number(),
diff --git a/tests/query-and.test.ts b/tests/query-and.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/index.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({
   id: z.number(),
diff --git a/tests/query-or.test.ts b/tests/query-or.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/index.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({
   id: z.number(),
diff --git a/tests/regressions/348-nested-relations.test.ts b/tests/regressions/348-nested-relations.test.ts
@@ -0,0 +1,40 @@
+import { z } from 'zod'
+import { Collection } from '#/src/collection.js'
+
+it('creates a record with a nested relation through another model', async () => {
+  const contactSchema = z.object({ email: z.email() })
+  const userSchema = z.object({
+    id: z.number(),
+    contact: contactSchema,
+  })
+  const postSchema = z.object({
+    title: z.string(),
+    author: userSchema,
+  })
+
+  const contacts = new Collection({ schema: contactSchema })
+  const users = new Collection({ schema: userSchema })
+  const posts = new Collection({ schema: postSchema })
+
+  users.defineRelations(({ one }) => ({
+    contact: one(contacts),
+  }))
+  posts.defineRelations(({ one }) => ({
+    author: one(users),
+  }))
+
+  const contact = await contacts.create({ email: 'john@example.com' })
+  expect(contact).toEqual({ email: 'john@example.com' })
+
+  const user = await users.create({ id: 1, contact })
+  expect(user).toEqual({ id: 1, contact: { email: 'john@example.com' } })
+
+  const post = await posts.create({ title: 'First', author: user })
+  expect(post).toEqual({
+    title: 'First',
+    author: {
+      id: 1,
+      contact: { email: 'john@example.com' },
+    },
+  })
+})
diff --git a/tests/relations/many-to-many.test.ts b/tests/relations/many-to-many.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const userSchema = z.object({
   id: z.number(),
diff --git a/tests/relations/many-to-one.test.ts b/tests/relations/many-to-one.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/index.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const userSchema = z.object({
   id: z.number(),
diff --git a/tests/relations/one-to-many.test.ts b/tests/relations/one-to-many.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/index.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const userSchema = z.object({
   id: z.number(),
diff --git a/tests/relations/one-to-one.test.ts b/tests/relations/one-to-one.test.ts
@@ -1,14 +1,14 @@
+import { z } from 'zod'
 import { Collection, RelationError, RelationErrorCodes } from '#/src/index.js'
 import { isRecord } from '#/src/utils.js'
-import z from 'zod'
 
 const countrySchema = z.object({
   code: z.string(),
 })
 
 const userSchema = z.object({
   id: z.number(),
-  country: countrySchema.optional(),
+  country: countrySchema,
 })
 
 it('supports a one-to-one relation', async () => {
diff --git a/tests/relations/polymorphic.test.ts b/tests/relations/polymorphic.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const imageSchema = z.object({
   src: z.string(),
diff --git a/tests/sort.test.ts b/tests/sort.test.ts
@@ -1,5 +1,5 @@
 import { Collection } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({
   id: z.number(),
diff --git a/tests/types/create-many.test-d.ts b/tests/types/create-many.test-d.ts
@@ -1,5 +1,5 @@
 import { Collection, type RecordType } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('infers the initial value factory and return types from the schema', () => {
   const users = new Collection({ schema: z.object({ id: z.number() }) })
diff --git a/tests/types/create.test-d.ts b/tests/types/create.test-d.ts
@@ -1,5 +1,5 @@
 import { Collection, type RecordType } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('infers initial values from primitives in the schema', async () => {
   expectTypeOf(new Collection({ schema: z.object({ id: z.number() }) }).create)
diff --git a/tests/types/delete-many.test-d.ts b/tests/types/delete-many.test-d.ts
@@ -1,6 +1,6 @@
 import { Collection, type RecordType } from '#/src/collection.js'
 import type { SortDirection } from '#/src/sort.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('infers return type from the schema', () => {
   const users = new Collection({
diff --git a/tests/types/delete.test-d.ts b/tests/types/delete.test-d.ts
@@ -1,5 +1,5 @@
 import { Collection, type RecordType } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('does not require a query argument', () => {
   const users = new Collection({
diff --git a/tests/types/find-first.test-d.ts b/tests/types/find-first.test-d.ts
@@ -1,5 +1,5 @@
 import { Collection, type RecordType } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('does not require a query argument', () => {
   const users = new Collection({
diff --git a/tests/types/find-many.test-d.ts b/tests/types/find-many.test-d.ts
@@ -1,6 +1,6 @@
 import { Collection, type RecordType } from '#/src/collection.js'
 import type { SortDirection } from '#/src/sort.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('does not require a query argument', () => {
   const users = new Collection({
diff --git a/tests/types/update-many.test-d.ts b/tests/types/update-many.test-d.ts
@@ -4,7 +4,7 @@ import {
   type UpdateFunction,
 } from '#/src/collection.js'
 import type { SortDirection } from '#/src/sort.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('infers return type from the schema', () => {
   const users = new Collection({
diff --git a/tests/types/update.test-d.ts b/tests/types/update.test-d.ts
@@ -3,7 +3,7 @@ import {
   type RecordType,
   type UpdateFunction,
 } from '#/src/collection.js'
-import z from 'zod'
+import { z } from 'zod'
 
 it('infers return type from the schema', () => {
   const users = new Collection({
diff --git a/tests/update-many.test.ts b/tests/update-many.test.ts
@@ -1,5 +1,5 @@
 import { Collection, Query } from '#/src/index.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const userSchema = z.object({
   id: z.number(),
diff --git a/tests/update.test.ts b/tests/update.test.ts
@@ -1,5 +1,5 @@
 import { Collection, Query } from '#/src/index.js'
-import z from 'zod'
+import { z } from 'zod'
 
 const schema = z.object({ id: z.number(), name: z.string() })
 
