Process multiple update for the same new entity

packages/toolkit/src/entities/sorted_state_adapter.ts

@@ -160,12 +160,12 @@ export function createSortedStateAdapter<T, Id extends EntityId>(
       state,
     )
 
-    if (updated.length) {
-      updateManyMutably(updated, state)
-    }
     if (added.length) {
       addManyMutably(added, state, existingIdsArray)
     }
+    if (updated.length) {
+      updateManyMutably(updated, state)
+    }
   }
 
   function areArraysEqual(a: readonly unknown[], b: readonly unknown[]) {

packages/toolkit/src/entities/unsorted_state_adapter.ts

@@ -183,8 +183,8 @@ export function createUnsortedStateAdapter<T, Id extends EntityId>(
       state,
     )
 
-    updateManyMutably(updated, state)
     addManyMutably(added, state)
+    updateManyMutably(updated, state)
   }
 
   return {

packages/toolkit/src/entities/utils.ts

@@ -52,13 +52,15 @@ export function splitAddedUpdatedEntities<T, Id extends EntityId>(
   const existingIds = new Set<Id>(existingIdsArray)
 
   const added: T[] = []
+  const addedIds = new Set<Id>([])
   const updated: Update<T, Id>[] = []
 
   for (const entity of newEntities) {
     const id = selectIdValue(entity, selectId)
-    if (existingIds.has(id)) {
+    if (existingIds.has(id) || addedIds.has(id)) {
       updated.push({ id, changes: entity })
     } else {
+      addedIds.add(id)
       added.push(entity)
     }
   }

packages/toolkit/src/tests/createEntityAdapter.test.ts

@@ -0,0 +1,53 @@
+import { createAction, createEntityAdapter, type EntityId } from '@reduxjs/toolkit'
+
+describe('createEntityAdapter', () => {
+  describe('CRUD operations', () => {
+    describe('upsertMany', () => {
+      type Entity = {
+        id: EntityId
+        value?: string
+        value2?: number
+      }
+
+      const entity1 = { id: 1 }
+      const entity2 = { id: 2 }
+      const update1 = { id: 1, value: 'hello' }
+      const update2 = { id: 1, value: 'world' }
+      const update3 = { id: 1, value2: 42 }
+      const adapter = createEntityAdapter<Entity>()
+      const anyAction = createAction<Entity[]>('anyAction')
+      const { selectAll } = adapter.getSelectors()
+
+      describe('when adding new entities', () => {
+        const initialState = adapter.setOne(adapter.getInitialState({}), entity1)
+        const upsertAction = anyAction([entity2])
+
+        it('should add a new entity to the state', () => {
+          expect(selectAll(adapter.upsertMany(initialState, upsertAction))).toEqual([entity1, entity2])
+        })
+      })
+
+      describe('when updating existing entities', () => {
+        const initialState = adapter.setOne(adapter.getInitialState({}), entity1)
+        const upsertAction = anyAction([update1, update2, update3])
+
+        it('should update existing entity with multiple updates', () => {
+          expect(selectAll(adapter.upsertMany(initialState, upsertAction))).toEqual([
+            Object.assign({}, entity1, update1, update2, update3),
+          ])
+        })
+      })
+
+      describe('when applying updates to non-existing entities', () => {
+        const initialState = adapter.getInitialState({})
+        const upsertAction = anyAction([update1, update2, update3])
+
+        it('should add the new entity and apply related updates', () => {
+          expect(selectAll(adapter.upsertMany(initialState, upsertAction))).toEqual([
+            Object.assign({}, update1, update2, update3),
+          ])
+        })
+      })
+    })
+  })
+})