Adapting /groupBy/tag csv response (#33)

an empty result is given if no feature matches the filter closes #25
GIScience · Aug 27, 2020 · ec4bacf · ec4bacf
1 parent a8856c9
commit ec4bacf
Showing 1 changed file with 10 additions and 4 deletions.
diff --git a/src/main/java/org/heigit/ohsome/ohsomeapi/executor/ExecutionUtils.java b/src/main/java/org/heigit/ohsome/ohsomeapi/executor/ExecutionUtils.java
@@ -291,11 +291,17 @@ public void writeCsvResponse(GroupByObject[] resultSet, HttpServletResponse serv
       CSVWriter writer = writeComments(servletResponse, comments);
       Pair<List<String>, List<String[]>> rows;
       if (resultSet instanceof GroupByResult[]) {
-        GroupByResult result = (GroupByResult) resultSet[0];
-        if (result.getResult() instanceof UsersResult[]) {
-          rows = createCsvResponseForUsersGroupBy(resultSet);
+        if (resultSet.length == 0) {
+          writer.writeNext(new String[] {"timestamp"}, false);
+          writer.close();
+          return;
         } else {
-          rows = createCsvResponseForElementsGroupBy(resultSet);
+          GroupByResult result = (GroupByResult) resultSet[0];
+          if (result.getResult() instanceof UsersResult[]) {
+            rows = createCsvResponseForUsersGroupBy(resultSet);
+          } else {
+            rows = createCsvResponseForElementsGroupBy(resultSet);
+          }
         }
       } else {
         rows = createCsvResponseForElementsRatioGroupBy(resultSet);