feat(repository): allow components to contribute models for DI

Add a new optional property `models` to `Component` interface, to allow
extension developers to declaratively contribute model classes to be
bound in the target context.

Signed-off-by: Miroslav Bajtoš <mbajtoss@gmail.com>

packages/repository/src/__tests__/unit/mixins/repository.mixin.unit.ts

@@ -11,6 +11,7 @@ import {
   DefaultCrudRepository,
   Entity,
   juggler,
+  Model,
   ModelDefinition,
   Repository,
   RepositoryMixin,
@@ -77,6 +78,23 @@ describe('RepositoryMixin', () => {
     expectNoteRepoToBeBound(myApp);
   });
 
+  it('binds user defined component with models', () => {
+    @model()
+    class MyModel extends Model {}
+
+    class MyModelComponent {
+      models = [MyModel];
+    }
+
+    const myApp = new AppWithRepoMixin();
+    myApp.component(MyModelComponent);
+
+    const boundModels = myApp.find('models.*').map(b => b.key);
+    expect(boundModels).to.containEql('models.MyModel');
+    const modelCtor = myApp.getSync<typeof MyModel>('models.MyModel');
+    expect(modelCtor).to.be.equal(MyModel);
+  });
+
   context('migrateSchema', () => {
     let app: AppWithRepoMixin;
     let migrateStub: sinon.SinonStub;

packages/repository/src/mixins/repository.mixin.ts

@@ -221,28 +221,59 @@ export function RepositoryMixin<T extends MixinTarget<Application>>(
       nameOrOptions?: string | BindingFromClassOptions,
     ) {
       const binding = super.component(componentCtor, nameOrOptions);
-      this.mountComponentRepositories(componentCtor);
+      const instance = this.getSync<C & RepositoryComponent>(binding.key);
+      this.mountComponentRepositories(instance);
+      this.mountComponentModels(instance);
       return binding;
     }
 
     /**
      * Get an instance of a component and mount all it's
      * repositories. This function is intended to be used internally
-     * by component()
+     * by `component()`.
      *
-     * @param component - The component to mount repositories of
+     * NOTE: Calling `mountComponentRepositories` with a component class
+     * constructor is deprecated. You should instantiate the component
+     * yourself and provide the component instance instead.
+     *
+     * @param componentInstanceOrClass - The component to mount repositories of
+     * @internal
      */
-    mountComponentRepositories(component: Class<unknown>) {
-      const componentKey = `${CoreBindings.COMPONENTS}.${component.name}`;
-      const compInstance = this.getSync<{
-        repositories?: Class<Repository<Model>>[];
-      }>(componentKey);
+    mountComponentRepositories(
+      // accept also component class to preserve backwards compatibility
+      // TODO(semver-major) Remove support for component class constructor
+      componentInstanceOrClass: Class<unknown> | RepositoryComponent,
+    ) {
+      const component = resolveComponentInstance(this);
 
-      if (compInstance.repositories) {
-        for (const repo of compInstance.repositories) {
+      if (component.repositories) {
+        for (const repo of component.repositories) {
           this.repository(repo);
         }
       }
+
+      // `Readonly<Application>` is a hack to remove protected members
+      // and thus allow `this` to be passed as a value for `ctx`
+      function resolveComponentInstance(ctx: Readonly<Application>) {
+        if (typeof componentInstanceOrClass !== 'function')
+          return componentInstanceOrClass;
+
+        const componentName = componentInstanceOrClass.name;
+        const componentKey = `${CoreBindings.COMPONENTS}.${componentName}`;
+        return ctx.getSync<RepositoryComponent>(componentKey);
+      }
+    }
+
+    /**
+     * Bind all model classes provided by a component.
+     * @param component
+     * @internal
+     */
+    mountComponentModels(component: RepositoryComponent) {
+      if (!component.models) return;
+      for (const m of component.models) {
+        this.model(m);
+      }
     }
 
     /**
@@ -287,6 +318,24 @@ export function RepositoryMixin<T extends MixinTarget<Application>>(
   };
 }
 
+/**
+ * This interface describes additional Component properties
+ * allowing components to contribute Repository-related artifacts.
+ */
+export interface RepositoryComponent {
+  /**
+   * An optional list of Repository classes to bind for dependency injection
+   * via `app.repository()` API.
+   */
+  repositories?: Class<Repository<Model>>[];
+
+  /**
+   * An optional list of Model classes to bind for dependency injection
+   * via `app.model()` API.
+   */
+  models?: Class<Model>[];
+}
+
 /**
  * Normalize name or options to `BindingFromClassOptions`
  * @param nameOrOptions - Name or options for binding from class