Issues 252,253: Browse by title and browse by metadata (author)

src/app/core/shared/operators.ts

@@ -1,6 +1,6 @@
 import { Observable } from 'rxjs/Observable';
 import { filter, flatMap, map, tap } from 'rxjs/operators';
-import { hasValueOperator } from '../../shared/empty.util';
+import { hasValueOperator, isNotEmpty } from '../../shared/empty.util';
 import { DSOSuccessResponse } from '../cache/response-cache.models';
 import { ResponseCacheEntry } from '../cache/response-cache.reducer';
 import { ResponseCacheService } from '../cache/response-cache.service';
@@ -8,6 +8,7 @@ import { RemoteData } from '../data/remote-data';
 import { RestRequest } from '../data/request.models';
 import { RequestEntry } from '../data/request.reducer';
 import { RequestService } from '../data/request.service';
+import { BrowseDefinition } from './browse-definition.model';
 
 /**
  * This file contains custom RxJS operators that can be used in multiple places
@@ -45,3 +46,19 @@ export const configureRequest = (requestService: RequestService) =>
 export const getRemoteDataPayload = () =>
   <T>(source: Observable<RemoteData<T>>): Observable<T> =>
     source.pipe(map((remoteData: RemoteData<T>) => remoteData.payload));
+
+export const getBrowseDefinitionLinks = (definitionID: string) =>
+  (source: Observable<RemoteData<BrowseDefinition[]>>): Observable<any> =>
+    source.pipe(
+      getRemoteDataPayload(),
+      map((browseDefinitions: BrowseDefinition[]) => browseDefinitions
+        .find((def: BrowseDefinition) => def.id === definitionID && def.metadataBrowse === true)
+      ),
+      map((def: BrowseDefinition) => {
+        if (isNotEmpty(def)) {
+          return def._links;
+        } else {
+          throw new Error(`No metadata browse definition could be found for id '${definitionID}'`);
+        }
+      })
+    );