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Exercise 4: Optional exercise

You can earn an additional +3 points with the completion of this exercise. (In the evaluation, you will see the text "imsc" in the exercise title; this is meant for the Hungarian students. Please ignore that.)

If we have lots of tasks listing them should not return all of them at once. Implement a new endpoint to return a subset of the tasks (i.e., "paging"):

  • It returns the tasks in a deterministic fashion sorted by ID.
  • The query accepts a count parameter that specifies how many tasks to return.
  • Specifying the next page is performed via a from parameter. This from is the ID of the first item to return on this page.
  • Both the from and count are specified as query parameters.
  • The new paging endpoint should be available on URL GET /api/tasks/neptun/paged (the /paged part is necessary so that the previous listing endpoint also remains functional).

  • The response should return an instance of class Controllers.Dto.PagedTaskList. This includes:

    • items: an array containing the tasks on the current page,
    • count: specifying the number of items on the current page,
    • nextId: id of the next task - to fetch the next page (to be used in from),

    • nextUrl: a helper URL that fetches the next page, or null if there are no further pages.

      Use the Url.Action helper method to assemble this URL. Do not hardcode "localhost:5000" or "/api/tasks/paged" in the source code! You will not need string operations to achieve this.

      Url.Action will give you an absolute URL when all parameters (action, controller, values, protocol, and host) are specified; for the latter ones this.HttpContext.Request can provide you the required values.

  • The request always returns 200 OK; if there are no items, the result set shall be empty.

The requests-responses shows you the expected behavior:

  1. GET /api/tasks/neptun/paged?count=2

    This is the first request. There is no from value specified to start from the first item.

    Response:

    {
  "items": [
    {
      "id": 1,
      "title": "doing homework",
      "done": false,
      "status": "pending"
    },
    {
      ID: 2,
      "title": "doing more homework",
      "done": false,
      "status": "new"
    }
  ],
  "count": 2,
  "nextId": 3,
  "nextUrl": "http://localhost:5000/api/tasks/neptun/paged?from=3&count=2"
}

  2. GET /api/tasks/neptun/paged?from=3&count=2

    This is to query the second page.

    Response:

    {
  "items": [
    {
      "id": 3,
      "title": "hosework",
      "done": true,
      "status": "done"
    }
  ],
  "count": 1,
  "nextId": null,
  "nextUrl": null
}

    The response indicates no further pages as both nextId and nextUrl are null.

  3. GET /api/tasks/neptun/paged?from=999&count=999

    Returns an empty page.

    Response:

    {
  "items": [],
  "count": 0,
  "nextId": null,
  "nextUrl": null
}

SUBMISSION

Create a screenshot in Postman (or an alternative tool you used) that shows an arbitrary request and response of fetching a page. Save the screenshot as f4.png and submit it with the other files of the solution. The screenshot shall include both the request and the response with all details (URL, body, response code, response body). Verify that your Neptun code is visible in the URL! The screenshot is required to earn the points.

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