[DRAFT] Experiment: Add "indices" to entity adapter

etc/redux-toolkit.api.md

@@ -144,10 +144,7 @@ export function createAsyncThunk<Returned, ThunkArg = void, ThunkApiConfig exten
 export const createDraftSafeSelector: typeof createSelector;
 
 // @public (undocumented)
-export function createEntityAdapter<T>(options?: {
-    selectId?: IdSelector<T>;
-    sortComparer?: false | Comparer<T>;
-}): EntityAdapter<T>;
+export function createEntityAdapter<T>(options?: EntityDefinition<T>): EntityAdapter<T>;
 
 // @public
 export function createImmutableStateInvariantMiddleware(options?: ImmutableStateInvariantMiddlewareOptions): Middleware;
@@ -230,6 +227,8 @@ export interface EntityState<T> {
     entities: Dictionary<T>;
     // (undocumented)
     ids: EntityId[];
+    // (undocumented)
+    indices: Indices<T, IndexComparers<T>>;
 }
 
 // @public (undocumented)

src/entities/create_adapter.ts

@@ -1,4 +1,9 @@
-import { EntityDefinition, Comparer, IdSelector, EntityAdapter } from './models'
+import {
+  EntityDefinition,
+  Comparer,
+  EntityAdapter,
+  IndexComparers
+} from './models'
 import { createInitialStateFactory } from './entity_state'
 import { createSelectorsFactory } from './state_selectors'
 import { createSortedStateAdapter } from './sorted_state_adapter'
@@ -10,22 +15,20 @@ import { createUnsortedStateAdapter } from './unsorted_state_adapter'
  *
  * @public
  */
+
 export function createEntityAdapter<T>(
-  options: {
-    selectId?: IdSelector<T>
-    sortComparer?: false | Comparer<T>
-  } = {}
+  options?: EntityDefinition<T>
 ): EntityAdapter<T> {
-  const { selectId, sortComparer }: EntityDefinition<T> = {
-    sortComparer: false,
+  const { selectId, sortComparer, indices = {} as IndexComparers<T> } = {
+    sortComparer: false as const,
     selectId: (instance: any) => instance.id,
     ...options
   }
 
-  const stateFactory = createInitialStateFactory<T>()
+  const stateFactory = createInitialStateFactory<T, IndexComparers<T>>(indices)
   const selectorsFactory = createSelectorsFactory<T>()
   const stateAdapter = sortComparer
-    ? createSortedStateAdapter(selectId, sortComparer)
+    ? createSortedStateAdapter(selectId, sortComparer as Comparer<T>, indices)
     : createUnsortedStateAdapter(selectId)
 
   return {

src/entities/entity_state.test.ts

@@ -6,6 +6,18 @@ import { BookModel } from './fixtures/book'
 describe('Entity State', () => {
   let adapter: EntityAdapter<BookModel>
 
+  const adapter2 = createEntityAdapter<BookModel>({
+    selectId: (book: BookModel) => book.id,
+    indices: {
+      // TODO These should be BookModel, not unknown
+      id: (a, b) => a.id.localeCompare(b.id)
+    }
+  })
+
+  const tempState = adapter2.getInitialState()
+  // TODO should be an empty array
+  console.log(tempState.indices.id)
+
   beforeEach(() => {
     adapter = createEntityAdapter({
       selectId: (book: BookModel) => book.id
@@ -17,7 +29,8 @@ describe('Entity State', () => {
 
     expect(initialState).toEqual({
       ids: [],
-      entities: {}
+      entities: {},
+      indices: {}
     })
   })
 
@@ -29,7 +42,8 @@ describe('Entity State', () => {
     expect(initialState).toEqual({
       ...additionalProperties,
       ids: [],
-      entities: {}
+      entities: {},
+      indices: {}
     })
   })
 

src/entities/entity_state.ts

@@ -1,19 +1,33 @@
-import { EntityState } from './models'
+import { EntityState, IndexComparers, Indices } from './models'
+
+export function getInitialEntityState<V, IC extends IndexComparers<V>>(
+  indexComparers: IC
+): EntityState<V> {
+  const indices = {} as Indices<V, IC>
+
+  for (let key in indexComparers) {
+    indices[key] = []
+  }
 
-export function getInitialEntityState<V>(): EntityState<V> {
   return {
     ids: [],
-    entities: {}
+    entities: {},
+    indices
   }
 }
 
-export function createInitialStateFactory<V>() {
+export function createInitialStateFactory<V, IC extends IndexComparers<V>>(
+  indexComparers: IC
+) {
   function getInitialState(): EntityState<V>
   function getInitialState<S extends object>(
     additionalState: S
   ): EntityState<V> & S
   function getInitialState(additionalState: any = {}): any {
-    return Object.assign(getInitialEntityState(), additionalState)
+    return Object.assign(
+      getInitialEntityState(indexComparers as any),
+      additionalState
+    )
   }
 
   return { getInitialState }