frontend-app-api: Add getData method to ExtensionInstance

Co-authored-by: Patrik Oldsberg <poldsberg@gmail.com>
Co-authored-by: Philipp Hugenroth <philipph@spotify.com>
Signed-off-by: Johan Haals <johan.haals@gmail.com>

packages/frontend-app-api/src/wiring/createApp.tsx

@@ -174,13 +174,8 @@ export function createApp(options: {
   return {
     createRoot() {
       const rootComponents = rootInstances
-        .map(
-          e =>
-            e.data.get(
-              coreExtensionData.reactComponent.id,
-            ) as typeof coreExtensionData.reactComponent.T,
-        )
-        .filter(Boolean);
+        .map(e => e.getData(coreExtensionData.reactComponent))
+        .filter((x): x is React.ComponentType => !!x);
       return (
         <ApiProvider apis={apiHolder}>
           <AppContextProvider appContext={appContext}>
@@ -254,13 +249,8 @@ function createApiHolder(
   const apiFactories =
     coreExtension.attachments
       .get('apis')
-      ?.map(
-        e =>
-          e.data.get(
-            coreExtensionData.apiFactory.id,
-          ) as typeof coreExtensionData.apiFactory.T,
-      )
-      .filter(Boolean) ?? [];
+      ?.map(e => e.getData(coreExtensionData.apiFactory))
+      .filter((x): x is AnyApiFactory => !!x) ?? [];
 
   for (const factory of apiFactories) {
     factoryRegistry.register('default', factory);
@@ -307,10 +297,8 @@ export function extractRouteInfoFromInstanceTree(
   const results = new Map<RouteRef, string>();
 
   function visit(current: ExtensionInstance, basePath: string) {
-    const routePath = current.data.get(coreExtensionData.routePath.id) ?? '';
-    const routeRef = current.data.get(
-      coreExtensionData.routeRef.id,
-    ) as RouteRef;
+    const routePath = current.getData(coreExtensionData.routePath) ?? '';
+    const routeRef = current.getData(coreExtensionData.routeRef);
 
     // TODO: join paths in a more robust way
     const fullPath = basePath + routePath;

packages/frontend-app-api/src/wiring/createExtensionInstance.ts

@@ -14,16 +14,20 @@
  * limitations under the License.
  */
 
-import { BackstagePlugin, Extension } from '@backstage/frontend-plugin-api';
+import {
+  BackstagePlugin,
+  Extension,
+  ExtensionDataRef,
+} from '@backstage/frontend-plugin-api';
 import mapValues from 'lodash/mapValues';
 
 /** @internal */
 export interface ExtensionInstance {
   readonly id: string;
   /**
-   * Maps extension data ref IDs to extensions produced.
+   * Get concrete value for the given extension data reference. Returns undefined if no value is available.
    */
-  readonly data: Map<string, unknown>;
+  getData<T>(ref: ExtensionDataRef<T>): T | undefined;
   /**
    * Maps input names to the actual instances given to them.
    */
@@ -70,7 +74,7 @@ export function createExtensionInstance(options: {
         ({ extensionData: pointData }, inputName) => {
           // TODO: validation
           return (attachments.get(inputName) ?? []).map(attachment =>
-            mapValues(pointData, ref => attachment.data.get(ref.id)),
+            mapValues(pointData, ref => attachment.getData(ref)),
           );
         },
       ),
@@ -83,7 +87,10 @@ export function createExtensionInstance(options: {
 
   return {
     id: options.extension.id,
-    data: extensionData,
+    getData<T>(ref: ExtensionDataRef<T>): T | undefined {
+      return extensionData.get(ref.id) as T | undefined;
+    },
+
     attachments,
     $$type: 'extension-instance',
   };