Bugfix/1077 apps page reload pagination

[BeriBoss]

Bug: Incorrect Pagination on the Apps Page

The pagination on the Apps page was faulty. When on the page, a list of app servers with their apps was displayed, but neither the correct number of app servers (not the selected maximum results per page) nor the correct number of pages for all results was displayed.

Incorrect Behavior: If the maximum number of results per page was set to 10 and there were a total of 50 results, 7 app servers were displayed on the first page, but it was indicated that there were 5 pages. On the next page, 3 app servers were displayed, etc.

Correct Solution: 10 app servers should be displayed per page and it should be indicated that there are 5 pages.

Cause of the Error: The error was in the backend. The idea was that the frontend could make a REST call and specify the following query parameters:

• start
• limit
• appServerName
• releaseId

The endpoint should then return the filtered result with the correct offset (which page am I on) and the correct maximum number of results per page.

First Problem: The total number of results ( result.getB() ) was always returned as the number of all unfiltered Resource Entities with the ResourceType = APPLICATIONSERVER.

ch.mobi.itc.mobiliar.rest.apps.AppsRest#getApps:

return Response.status(OK).entity(appServersToResponse(result.getA())).header("X-total-count", result.getB()).build();

Solution to that would have been:

return Response.status(OK).entity(appServersToResponse(result.getA())).header("X-total-count", result.getA().size()).build();

Second Problem: Even if the total number of results had been corrected, the pagination would still not have worked. The reason for this was that the endpoint set a query that retrieved all Resource Entities with the ResourceType = APPLICATIONSERVER and the filtered name. The offset and limit were then set in the query:

   if (startIndex != null) {
            query.setFirstResult(startIndex);
        }
        
    if (maxResult != null) {
            query.setMaxResults(maxResult);
        }

The idea was to reduce the load time by only retrieving the "paginated" results directly. However, the problem was that this already paginated list of results was filtered twice in the business logic, so that the set start and limit no longer matched the final list.

Solution: The original solution would have been to correct the pagination, but this would have increased the load time (See commit: b695fa0 ). Since the DB was already under load, it was decided to remove the pagination and initially display only the first 20 app servers, as it was in the old version.

[llorentelemmc]

Right now, only a single app server is added to this list. Making the test more robust by mocking multiple application servers would be beneficial