feat(types): infer args and returned value for onAction

__tests__/onAction.spec.ts

@@ -68,16 +68,16 @@ describe('Subscriptions', () => {
 
   it('calls after with the returned value', async () => {
     const spy = jest.fn()
-    store.$onAction(({ after, name, store }) => {
-      name
-      if (name === 'upperName') {
-        after((ret) => {
+    // Cannot destructure because of https://github.com/microsoft/TypeScript/issues/38020
+    store.$onAction((context) => {
+      if (context.name === 'upperName') {
+        context.after((ret) => {
           // @ts-expect-error
           ret * 2
           ret.toUpperCase()
         })
       }
-      after(spy)
+      context.after(spy)
     })
     expect(store.upperName()).toBe('EDUARDO')
     await nextTick()

src/devtools/plugin.ts

@@ -6,7 +6,7 @@ import {
   GettersTree,
   MutationType,
   StateTree,
-  _Method,
+  ActionsTree,
 } from '../types'
 import {
   formatEventData,
@@ -259,7 +259,7 @@ export function devtoolsPlugin<
   Id extends string = string,
   S extends StateTree = StateTree,
   G extends GettersTree<S> = GettersTree<S>,
-  A = Record<string, _Method>
+  A /* extends ActionsTree */ = ActionsTree
 >({ app, store, options, pinia }: PiniaPluginContext<Id, S, G, A>) {
   const wrappedActions = {} as Pick<typeof store, keyof A>
 
@@ -295,7 +295,8 @@ export function devtoolsPlugin<
     }
   }
 
-  addDevtools(app, store)
+  // FIXME: can this be fixed?
+  addDevtools(app, store as unknown as Store)
 
   return { ...wrappedActions }
 }

src/mapHelpers.ts

@@ -5,6 +5,7 @@ import {
   StateTree,
   Store,
   StoreDefinition,
+  ActionsTree,
 } from './types'
 
 /**
@@ -55,14 +56,20 @@ function getCachedStore<
   Id extends string = string,
   S extends StateTree = StateTree,
   G extends GettersTree<S> = GettersTree<S>,
-  A = Record<string, _Method>
+  A /* extends ActionsTree */ = ActionsTree
 >(
   vm: ComponentPublicInstance,
   useStore: StoreDefinition<Id, S, G, A>
 ): Store<Id, S, G, A> {
   const cache = '_pStores' in vm ? vm._pStores! : (vm._pStores = {})
   const id = useStore.$id
-  return (cache[id] || (cache[id] = useStore(vm.$pinia))) as Store<Id, S, G, A>
+  return (cache[id] ||
+    (cache[id] = useStore(vm.$pinia) as unknown as Store)) as unknown as Store<
+    Id,
+    S,
+    G,
+    A
+  >
 }
 
 export let mapStoreSuffix = 'Store'

src/rootStore.ts

@@ -8,6 +8,7 @@ import {
   DefineStoreOptions,
   Store,
   GettersTree,
+  ActionsTree,
 } from './types'
 
 /**
@@ -119,7 +120,7 @@ export interface PiniaPluginContext<
   Id extends string = string,
   S extends StateTree = StateTree,
   G extends GettersTree<S> = GettersTree<S>,
-  A = Record<string, _Method>
+  A /* extends ActionsTree */ = ActionsTree
 > {
   /**
    * pinia instance.

src/store.ts

@@ -28,6 +28,8 @@ import {
   GettersTree,
   MutationType,
   StoreOnActionListener,
+  UnwrapPromise,
+  ActionsTree,
 } from './types'
 import {
   getActivePinia,
@@ -92,12 +94,17 @@ function computedFromState<T, Id extends string>(
  * @param buildState - function to build the initial state
  * @param initialState - initial state applied to the store, Must be correctly typed to infer typings
  */
-function initStore<Id extends string, S extends StateTree>(
+function initStore<
+  Id extends string,
+  S extends StateTree,
+  G extends GettersTree<S>,
+  A /* extends ActionsTree */
+>(
   $id: Id,
   buildState: () => S = () => ({} as S),
   initialState?: S | undefined
 ): [
-  StoreWithState<Id, S>,
+  StoreWithState<Id, S, G, A>,
   { get: () => S; set: (newValue: S) => void },
   InjectionKey<Store>
 ] {
@@ -107,7 +114,7 @@ function initStore<Id extends string, S extends StateTree>(
 
   let isListening = true
   let subscriptions: SubscriptionCallback<S>[] = []
-  let actionSubscriptions: StoreOnActionListener[] = []
+  let actionSubscriptions: StoreOnActionListener<Id, S, G, A>[] = []
   let debuggerEvents: DebuggerEvent[] | DebuggerEvent
 
   function $patch(stateMutation: (state: S) => void): void
@@ -199,7 +206,7 @@ function initStore<Id extends string, S extends StateTree>(
     return removeSubscription
   }
 
-  function $onAction(callback: StoreOnActionListener) {
+  function $onAction(callback: StoreOnActionListener<Id, S, G, A>) {
     actionSubscriptions.push(callback)
 
     const removeSubscription = () => {
@@ -220,7 +227,7 @@ function initStore<Id extends string, S extends StateTree>(
     pinia.state.value[$id] = buildState()
   }
 
-  const storeWithState: StoreWithState<Id, S> = {
+  const storeWithState: StoreWithState<Id, S, G, A> = {
     $id,
     _p: pinia,
     _as: actionSubscriptions,
@@ -231,7 +238,7 @@ function initStore<Id extends string, S extends StateTree>(
     $subscribe,
     $onAction,
     $reset,
-  } as StoreWithState<Id, S>
+  } as StoreWithState<Id, S, G, A>
 
   const injectionSymbol = __DEV__
     ? Symbol(`PiniaStore(${$id})`)
@@ -269,9 +276,9 @@ function buildStoreToUse<
   Id extends string,
   S extends StateTree,
   G extends GettersTree<S>,
-  A extends Record<string, _Method>
+  A extends ActionsTree
 >(
-  partialStore: StoreWithState<Id, S>,
+  partialStore: StoreWithState<Id, S, G, A>,
   descriptor: StateDescriptor<S>,
   $id: Id,
   getters: G = {} as G,
@@ -295,11 +302,11 @@ function buildStoreToUse<
   for (const actionName in actions) {
     wrappedActions[actionName] = function (this: Store<Id, S, G, A>) {
       setActivePinia(pinia)
-      const args = Array.from(arguments)
+      const args = Array.from(arguments) as Parameters<A[typeof actionName]>
       const localStore = this || store
 
       let afterCallback: (
-        resolvedReturn: ReturnType<typeof actions[typeof actionName]>
+        resolvedReturn: UnwrapPromise<ReturnType<A[typeof actionName]>>
       ) => void = noop
       let onErrorCallback: (error: unknown) => void = noop
       function after(callback: typeof afterCallback) {
@@ -310,13 +317,17 @@ function buildStoreToUse<
       }
 
       partialStore._as.forEach((callback) => {
+        // @ts-expect-error
         callback({ args, name: actionName, store: localStore, after, onError })
       })
 
-      let ret: ReturnType<typeof actions[typeof actionName]>
+      let ret: ReturnType<A[typeof actionName]>
       try {
         ret = actions[actionName].apply(localStore, args as unknown as any[])
-        Promise.resolve(ret).then(afterCallback).catch(onErrorCallback)
+        Promise.resolve(ret)
+          // @ts-expect-error: can't work this out
+          .then(afterCallback)
+          .catch(onErrorCallback)
       } catch (error) {
         onErrorCallback(error)
         throw error
@@ -348,6 +359,7 @@ function buildStoreToUse<
 
   // apply all plugins
   pinia._p.forEach((extender) => {
+    // @ts-expect-error: conflict between A and ActionsTree
     assign(store, extender({ store, app: pinia._a, pinia, options }))
   })
 
@@ -362,7 +374,8 @@ export function defineStore<
   Id extends string,
   S extends StateTree,
   G extends GettersTree<S>,
-  A /* extends Record<string, StoreAction> */
+  // cannot extends ActionsTree because we loose the typings
+  A /* extends ActionsTree */
 >(options: DefineStoreOptions<Id, S, G, A>): StoreDefinition<Id, S, G, A> {
   const { id, state, getters, actions } = options
 
@@ -380,23 +393,29 @@ export function defineStore<
 
     let storeAndDescriptor = stores.get(id) as
       | [
-          StoreWithState<Id, S>,
+          StoreWithState<Id, S, G, A>,
           StateDescriptor<S>,
           InjectionKey<Store<Id, S, G, A>>
         ]
       | undefined
     if (!storeAndDescriptor) {
       storeAndDescriptor = initStore(id, state, pinia.state.value[id])
 
-      stores.set(id, storeAndDescriptor)
+      // annoying to type
+      stores.set(id, storeAndDescriptor as any)
 
-      const store = buildStoreToUse(
+      const store = buildStoreToUse<
+        Id,
+        S,
+        G,
+        // @ts-expect-error: A without extends
+        A
+      >(
         storeAndDescriptor[0],
         storeAndDescriptor[1],
         id,
         getters as GettersTree<S> | undefined,
-        actions as Record<string, _Method> | undefined,
-        // @ts-expect-error: because of the extend on Actions
+        actions as A | undefined,
         options
       )
 
@@ -412,13 +431,18 @@ export function defineStore<
     return (
       // null avoids the warning for not found injection key
       (hasInstance && inject(storeAndDescriptor[2], null)) ||
-      buildStoreToUse(
+      buildStoreToUse<
+        Id,
+        S,
+        G,
+        // @ts-expect-error: A without extends
+        A
+      >(
         storeAndDescriptor[0],
         storeAndDescriptor[1],
         id,
         getters as GettersTree<S> | undefined,
-        actions as Record<string, _Method> | undefined,
-        // @ts-expect-error: because of the extend on Actions
+        actions as A | undefined,
         options
       )
     )