feat(nuxt): add private option to useAsyncData (#29064)

docs/3.api/2.composables/use-async-data.md

@@ -65,6 +65,7 @@ const { data: posts } = await useAsyncData(
 - `handler`: an asynchronous function that must return a truthy value (for example, it should not be `undefined` or `null`) or the request may be duplicated on the client side
 - `options`:
   - `server`: whether to fetch the data on the server (defaults to `true`)
+  - `private`: when true, `server` will default to `false` on cached pages and `true` on uncached pages (defaults to `false`)
   - `lazy`: whether to resolve the async function after loading the route, instead of blocking client-side navigation (defaults to `false`)
   - `immediate`: when set to `false`, will prevent the request from firing immediately. (defaults to `true`)
   - `default`: a factory function to set the default value of the `data`, before the async function resolves - useful with the `lazy: true` or `immediate: false` option

packages/nuxt/src/app/composables/asyncData.ts

@@ -49,6 +49,11 @@ export interface AsyncDataOptions<
    * @default true
    */
   server?: boolean
+  /**
+   * When true, `server` will default to false on cached pages and true on uncached pages
+   * @default false
+   */
+  private?: false
   /**
    * Whether to resolve the async function after loading the route, instead of blocking client-side navigation
    * @default false
@@ -230,7 +235,8 @@ export function useAsyncData<
   const getDefaultCachedData = () => nuxtApp.isHydrating ? nuxtApp.payload.data[key] : nuxtApp.static.data[key]
 
   // Apply defaults
-  options.server = options.server ?? true
+  const cachedRoute = !!nuxtApp.ssrContext?.event?.context.cache
+  options.server = options.server ?? (options.private ? !cachedRoute : true)
   options.default = options.default ?? (getDefault as () => DefaultT)
   options.getCachedData = options.getCachedData ?? getDefaultCachedData