Why does one Web API method work, whereas the other does not?

Question

One of my Web API methods works perfectly, and the other not at all.

By works perfectly, I mean this:

The other one, though, doesn't seem to even know about itself. It answers the browser request with:

The code seems to be set up the same for both of them, so I don't know why one works like a charm and the other fails so thuddily.

The pertinent code is:

CONTROLLER

public class DepartmentsController : ApiController
{
    private readonly IDepartmentRepository _deptsRepository;

    public DepartmentsController(IDepartmentRepository deptsRepository)
    {
        if (deptsRepository == null)
        {
            throw new ArgumentNullException("deptsRepository is null");
        }
        _deptsRepository = deptsRepository;
    }

    [Route("api/Departments/Count")]
    public int GetCountOfDepartmentRecords()
    {
        return _deptsRepository.Get();
    }

    [Route("api/Departments")]
    public IEnumerable<Department> GetBatchOfDepartmentsByStartingID(int ID, int CountToFetch)
    {
        return _deptsRepository.Get(ID, CountToFetch);
    }

REPOSITORY

public class DepartmentRepository : IDepartmentRepository
{
    private readonly List<Department> departments = new List<Department>();

    public DepartmentRepository()
    {
        using (var conn = new OleDbConnection(
            @"Provider=Microsoft.ACE.OLEDB.12.0;User ID=Freebo;Password=RunningOnEmpty;Data Source=C:\CDBWin\DATA\CCRDAT42.MDB;Jet OLEDB:System database=C:\CDBWin\Data\nrbq.mdw"))
        {
            using (var cmd = conn.CreateCommand())
            {
                cmd.CommandText = "SELECT td_department_accounts.dept_no, IIF(ISNULL(t_accounts.name),'No Name provided',t_accounts.name) AS name FROM t_accounts INNER JOIN td_department_accounts ON t_accounts.account_no = td_department_accounts.account_no ORDER BY td_department_accounts.dept_no";
                cmd.CommandType = CommandType.Text;
                conn.Open();
                int i = 1;
                using (OleDbDataReader oleDbD8aReader = cmd.ExecuteReader())
                {
                    while (oleDbD8aReader != null && oleDbD8aReader.Read())
                    {
                        int deptNum = oleDbD8aReader.GetInt16(0);
                        string deptName = oleDbD8aReader.GetString(1);
                        Add(new Department { Id = i, AccountId = deptNum, Name = deptName });
                        i++;
                    }
                }
            }
        }
    }

    public int Get()
    {
        return departments.Count;
    }

    private Department Get(int ID) // called by Delete()
    {
        return departments.First(d => d.Id == ID);
    }

If entering:

http://shannon2:28642/api/Departments/Count 

in the browser works to execute the Controller's GetCountOfDepartmentRecords() method, why does entering:

 http://localhost:28642/api/Departments/5/6

(or:

 http://localhost:28642/api/Departments/1/5

etc) not work to execute the Controller's GetBatchOfDepartmentsByStartingID() method?

Answer 1

Your route is missing its parameters.

[Route("api/Departments/{ID:int}/{CountToFetch:int}")]

Answer 2

This question looks similar to your other question below:

Why is my Web API call returning "No action was found on the controller 'DPlatypus' that matches the request"?

If you are expecting the values to come from a non-query string part of a url, you need to define them in the route template. So, it should be

[Route("api/Departments/{id}/{countToFetch}")]

Following is a good article to read about routing and action selection in Web API:
http://www.asp.net/web-api/overview/web-api-routing-and-actions