为什么一个Web API方法有效，而另一个没有？

Question

我的一个Web API方法完美无缺，另一个根本没有。

完美地运作，我的意思是：

但是，另一个人似乎甚至都不了解自己。它通过以下方式回答浏览器请求：

这两个代码的代码似乎都是相同的，所以我不知道为什么一个代码就像魅力一样，而另一个代码却很失败。

相关代码是：

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);
    }

如果输入：

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

浏览器中的

用于执行Controller的GetCountOfDepartmentRecords（）方法，为什么输入：

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

（或

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

etc）无法执行Controller的GetBatchOfDepartmentsByStartingID（）方法？

Answer 1

您的路线缺少参数。

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

Answer 2

此问题与您在下面的其他问题类似：

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

如果您希望值来自URL的非查询字符串部分，则需要在路径模板中定义它们。所以，它应该是

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

以下是关于Web API中的路由和操作选择的好文章：
http://www.asp.net/web-api/overview/web-api-routing-and-actions