added ArangoDatabaseAsync.cursor()

Author: mpv1989

ChangeLog

@@ -1,3 +1,7 @@
+v4.1.12 (2017-04-xx)
+---------------------------
+* added ArangoDatabaseAsync.cursor()
+
 v4.1.11 (2017-03-24)
 ---------------------------
 * fixed exception handling in Connection

src/main/java/com/arangodb/ArangoDatabaseAsync.java

@@ -250,6 +250,7 @@ public CompletableFuture<Void> revokeAccess(final String user) {
 	 * @param type
 	 *            The type of the result (POJO class, VPackSlice, String for Json, or Collection/List/Map)
 	 * @return cursor of the results
+	 * @throws ArangoDBException
 	 */
 	public <T> CompletableFuture<ArangoCursorAsync<T>> query(
 		final String query,
@@ -259,30 +260,56 @@ public <T> CompletableFuture<ArangoCursorAsync<T>> query(
 		final Request request = queryRequest(query, bindVars, options);
 		final CompletableFuture<CursorEntity> execution = executor.execute(request, CursorEntity.class);
 		return execution.thenApply(result -> {
-			return new ArangoCursorAsync<>(this, new ArangoCursorExecute() {
-				@Override
-				public CursorEntity next(final String id) {
-					final CompletableFuture<CursorEntity> result = executor.execute(queryNextRequest(id),
-						CursorEntity.class);
-					try {
-						return result.get();
-					} catch (InterruptedException | ExecutionException e) {
-						throw new ArangoDBException(e);
-					}
-				}
+			return createCursor(result, type);
+		});
+	}
 
-				@Override
-				public void close(final String id) {
-					try {
-						executor.execute(queryCloseRequest(id), Void.class).get();
-					} catch (InterruptedException | ExecutionException e) {
-						throw new ArangoDBException(e);
-					}
-				}
-			}, type, result);
+	/**
+	 * Return an cursor from the given cursor-ID if still existing
+	 * 
+	 * @see <a href=
+	 *      "https://docs.arangodb.com/current/HTTP/AqlQueryCursor/AccessingCursors.html#read-next-batch-from-cursor">API
+	 *      Documentation</a>
+	 * @param cursorId
+	 *            The ID of the cursor
+	 * @param type
+	 *            The type of the result (POJO class, VPackSlice, String for Json, or Collection/List/Map)
+	 * @return cursor of the results
+	 * @throws ArangoDBException
+	 */
+	public <T> CompletableFuture<ArangoCursorAsync<T>> cursor(final String cursorId, final Class<T> type)
+			throws ArangoDBException {
+		final CompletableFuture<CursorEntity> execution = executor.execute(queryNextRequest(cursorId),
+			CursorEntity.class);
+		return execution.thenApply(result -> {
+			return createCursor(result, type);
 		});
 	}
 
+	private <T> ArangoCursorAsync<T> createCursor(final CursorEntity result, final Class<T> type) {
+		return new ArangoCursorAsync<>(this, new ArangoCursorExecute() {
+			@Override
+			public CursorEntity next(final String id) {
+				final CompletableFuture<CursorEntity> result = executor.execute(queryNextRequest(id),
+					CursorEntity.class);
+				try {
+					return result.get();
+				} catch (InterruptedException | ExecutionException e) {
+					throw new ArangoDBException(e);
+				}
+			}
+
+			@Override
+			public void close(final String id) {
+				try {
+					executor.execute(queryCloseRequest(id), Void.class).get();
+				} catch (InterruptedException | ExecutionException e) {
+					throw new ArangoDBException(e);
+				}
+			}
+		}, type, result);
+	}
+
 	/**
 	 * Explain an AQL query and return information about it
 	 * 

src/test/java/com/arangodb/ArangoDatabaseTest.java

@@ -522,6 +522,34 @@ public void queryWithCache() throws InterruptedException, ArangoDBException, Exe
 		}
 	}
 
+	@Test
+	public void queryCursor() throws ArangoDBException, InterruptedException, ExecutionException {
+		try {
+			db.createCollection(COLLECTION_NAME, null).get();
+			final int numbDocs = 10;
+			for (int i = 0; i < numbDocs; i++) {
+				db.collection(COLLECTION_NAME).insertDocument(new BaseDocument(), null).get();
+			}
+
+			final int batchSize = 5;
+			final ArangoCursorAsync<String> cursor = db.query("for i in db_test return i._id", null,
+				new AqlQueryOptions().batchSize(batchSize).count(true), String.class).get();
+			assertThat(cursor, is(notNullValue()));
+			assertThat(cursor.getCount(), is(numbDocs));
+
+			final ArangoCursorAsync<String> cursor2 = db.cursor(cursor.getId(), String.class).get();
+			assertThat(cursor2, is(notNullValue()));
+			assertThat(cursor2.getCount(), is(numbDocs));
+			assertThat(cursor2.hasNext(), is(true));
+
+			for (int i = 0; i < batchSize; i++, cursor.next()) {
+				assertThat(cursor.hasNext(), is(i != batchSize));
+			}
+		} finally {
+			db.collection(COLLECTION_NAME).drop().get();
+		}
+	}
+
 	@Test
 	public void changeQueryTrackingProperties() throws InterruptedException, ExecutionException {
 		try {