93803: Make data services composable

Data services should extend BaseDataService (or IdentifiableDataService) for low-level functionality and optionally wrap "data service feature" classes for
- create
- findAll
- patch / update
- put
- delete

src/app/core/data/base/create-data.ts

@@ -0,0 +1,107 @@
+/**
+ * The contents of this file are subject to the license and copyright
+ * detailed in the LICENSE and NOTICE files at the root of the source
+ * tree and available online at
+ *
+ * http://www.dspace.org/license/
+ */
+import { CacheableObject } from '../../cache/cacheable-object.model';
+import { BaseDataService } from './base-data.service';
+import { RequestParam } from '../../cache/models/request-param.model';
+import { Observable } from 'rxjs';
+import { RemoteData } from '../remote-data';
+import { hasValue, isNotEmptyOperator } from '../../../shared/empty.util';
+import { distinctUntilChanged, map, take, takeWhile } from 'rxjs/operators';
+import { DSpaceSerializer } from '../../dspace-rest/dspace.serializer';
+import { getClassForType } from '../../cache/builders/build-decorators';
+import { CreateRequest } from '../request.models';
+import { NotificationOptions } from '../../../shared/notifications/models/notification-options.model';
+import { RequestService } from '../request.service';
+import { RemoteDataBuildService } from '../../cache/builders/remote-data-build.service';
+import { HALEndpointService } from '../../shared/hal-endpoint.service';
+import { NotificationsService } from '../../../shared/notifications/notifications.service';
+import { ObjectCacheService } from '../../cache/object-cache.service';
+
+/**
+ * Interface for a data service that can create objects.
+ */
+export interface CreateData<T extends CacheableObject> {
+  /**
+   * Create a new DSpaceObject on the server, and store the response
+   * in the object cache
+   *
+   * @param object  The object to create
+   * @param params  Array with additional params to combine with query string
+   */
+  create(object: T, ...params: RequestParam[]): Observable<RemoteData<T>>;
+}
+
+/**
+ * A DataService feature to create objects.
+ *
+ * Concrete data services can use this feature by implementing {@link CreateData}
+ * and delegating its method to an inner instance of this class.
+ */
+export class CreateDataImpl<T extends CacheableObject> extends BaseDataService<T> implements CreateData<T> {
+  constructor(
+    protected linkPath: string,
+    protected requestService: RequestService,
+    protected rdbService: RemoteDataBuildService,
+    protected objectCache: ObjectCacheService,
+    protected halService: HALEndpointService,
+    protected notificationsService: NotificationsService,
+    protected responseMsToLive: number,
+  ) {
+    super(linkPath, requestService, rdbService, objectCache, halService, responseMsToLive);
+  }
+
+  /**
+   * Create a new object on the server, and store the response in the object cache
+   *
+   * @param object    The object to create
+   * @param params    Array with additional params to combine with query string
+   */
+  create(object: T, ...params: RequestParam[]): Observable<RemoteData<T>> {
+    const endpoint$ = this.getEndpoint().pipe(
+      isNotEmptyOperator(),
+      distinctUntilChanged(),
+      map((endpoint: string) => this.buildHrefWithParams(endpoint, params)),
+    );
+    return this.createOnEndpoint(object, endpoint$);
+  }
+
+  /**
+   * Send a POST request to create a new resource to a specific endpoint.
+   * Use this method if the endpoint needs to be adjusted. In most cases {@link create} should be sufficient.
+   * @param object     the object to create
+   * @param endpoint$  the endpoint to send the POST request to
+   */
+  createOnEndpoint(object: T, endpoint$: Observable<string>): Observable<RemoteData<T>> {
+    const requestId = this.requestService.generateRequestId();
+    const serializedObject = new DSpaceSerializer(getClassForType(object.type)).serialize(object);
+
+    endpoint$.pipe(
+      take(1),
+    ).subscribe((endpoint: string) => {
+      const request = new CreateRequest(requestId, endpoint, JSON.stringify(serializedObject));
+      if (hasValue(this.responseMsToLive)) {
+        request.responseMsToLive = this.responseMsToLive;
+      }
+      this.requestService.send(request);
+    });
+
+    const result$ = this.rdbService.buildFromRequestUUID<T>(requestId);
+
+    // TODO a dataservice is not the best place to show a notification,
+    // this should move up to the components that use this method
+    result$.pipe(
+      takeWhile((rd: RemoteData<T>) => rd.isLoading, true)
+    ).subscribe((rd: RemoteData<T>) => {
+      if (rd.hasFailed) {
+        this.notificationsService.error('Server Error:', rd.errorMessage, new NotificationOptions(-1));
+      }
+    });
+
+    return result$;
+  }
+}