feat(graphcache): add onCacheHydrated event (#3428)

urql-graphql · Dec 1, 2023 · d6e435c · d6e435c
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diff --git a/.changeset/stale-eagles-hide.md b/.changeset/stale-eagles-hide.md
@@ -0,0 +1,5 @@
+---
+'@urql/exchange-graphcache': minor
+---
+
+Add `onCacheHydrated` as an option for the `StorageAdapter`
diff --git a/docs/api/graphcache.md b/docs/api/graphcache.md
@@ -178,13 +178,14 @@ the cache's data to persisted storage on the user's device. it
 > **NOTE:** Offline Support is currently experimental! It hasn't been extensively tested yet and
 > may not always behave as expected. Please try it out with caution!
 
-| Method          | Type                                          | Description                                                                                                                                                                            |
-| --------------- | --------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `writeData`     | `(delta: SerializedEntries) => Promise<void>` | This provided method must be able to accept an object of key-value entries that will be persisted to the storage. This method is called as a batch of updated entries becomes ready.   |
-| `readData`      | `() => Promise<SerializedEntries>`            | This provided method must be able to return a single combined object of previous key-value entries that have been previously preserved using `writeData`. It's only called on startup. |
-| `writeMetadata` | `(json: SerializedRequest[]) => void`         | This provided method must be able to persist metadata for the cache. For backwards compatibility it should be able to accept any JSON data.                                            |
-| `readMetadata`  | `() => Promise<null \| SerializedRequest[]>`  | This provided method must be able to read the persisted metadata that has previously been written using `writeMetadata`. It's only called on startup.                                  |
-| `onOnline`      | `(cb: () => void) => void`                    | This method must be able to accept a callback that is called when the user's device comes back online.                                                                                 |
+| Method            | Type                                          | Description                                                                                                                                                                            |
+| ----------------- | --------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `writeData`       | `(delta: SerializedEntries) => Promise<void>` | This provided method must be able to accept an object of key-value entries that will be persisted to the storage. This method is called as a batch of updated entries becomes ready.   |
+| `readData`        | `() => Promise<SerializedEntries>`            | This provided method must be able to return a single combined object of previous key-value entries that have been previously preserved using `writeData`. It's only called on startup. |
+| `writeMetadata`   | `(json: SerializedRequest[]) => void`         | This provided method must be able to persist metadata for the cache. For backwards compatibility it should be able to accept any JSON data.                                            |
+| `readMetadata`    | `() => Promise<null \| SerializedRequest[]>`  | This provided method must be able to read the persisted metadata that has previously been written using `writeMetadata`. It's only called on startup.                                  |
+| `onOnline`        | `(cb: () => void) => void`                    | This method must be able to accept a callback that is called when the user's device comes back online.                                                                                 |
+| `onCacheHydrated` | `() => void`                                  | This method will be called when the `cacheExchange` has finished hydrating the data coming from storage.                                                                               |
 
 These options are split into three parts:
 

diff --git a/exchanges/graphcache/src/cacheExchange.ts b/exchanges/graphcache/src/cacheExchange.ts
@@ -73,6 +73,7 @@ export const cacheExchange =
       store.data.hydrating = true;
       opts.storage.readData().then(entries => {
         hydrateData(store.data, opts!.storage!, entries);
+        if (opts.storage!.onCacheHydrated) opts.storage!.onCacheHydrated();
       });
     }
 

diff --git a/exchanges/graphcache/src/default-storage/index.ts b/exchanges/graphcache/src/default-storage/index.ts
@@ -35,6 +35,8 @@ export interface StorageOptions {
    * @defaultValue `7` days
    */
   maxAge?: number;
+  /** Gets Called when the exchange has hydrated the data from storage. */
+  onCacheHydrated?: () => void;
 }
 
 /** Sample storage adapter persisting to IndexedDB. */
@@ -219,7 +221,7 @@ export const makeDefaultStorage = (opts?: StorageOptions): DefaultStorage => {
           () => batch
         );
     },
-
+    onCacheHydrated: opts.onCacheHydrated,
     onOnline(cb: () => void) {
       if (callback) {
         window.removeEventListener('online', callback);

diff --git a/exchanges/graphcache/src/types.ts b/exchanges/graphcache/src/types.ts
@@ -980,6 +980,8 @@ export interface StorageAdapter {
    * will cause all failed mutations in the queue to be retried.
    */
   onOnline?(cb: () => void): any;
+  /** Called when the cache has been hydrated with the data from `readData` */
+  onCacheHydrated?(): any;
 }
 
 /** Set of keys that have been modified or accessed.