c＃函數中的可選參數

Question

我必須在我的asp.net mvc項目模型中使用方法。

public JsonResult GetProductsByDepList(string depID) 
{ 
    JsonResult jr = new JsonResult(); 
    var _product = from a in DataContext.GetProductsByDep(Convert.ToInt32(depID)) 
    select new { ID = a.ID, ProName = a.Name }; 
    jr.Data = _product.ToList(); 
    jr.JsonRequestBehavior = JsonRequestBehavior.AllowGet; 
    return jr; 
} 


public JsonResult GetProductByCatList(string depID, string catID) 
{ 
    JsonResult jr = new JsonResult(); 
    var _product = from a in 
    DataContext.GetProductsByCat(Convert.ToInt32(depID),Convert.ToInt32(catID)) 
    select new { ID = a.ID, ProName = a.Name }; 
    jr.Data = _product.ToList(); 
    jr.JsonRequestBehavior = JsonRequestBehavior.AllowGet; 
    return jr; 
} 

我想結合這兩種方法，除了函數的參數以外，它們是一樣的。

任何想法請。

Answer 1

使用optional argument：

public JsonResult GetProductByCatList(string depID, string catID = "0") 

Answer 2

public JsonResult GetProductByCatList(string depID, string catID = "-1") 
{ 
    //common shared code 
    return jr; 
} 

假設默認值是-1爲catID

Answer 3

你可以嘗試：

public JsonResult GetProductByCatList(string depID, string catID = null) 
{ 
    JsonResult jr = new JsonResult(); 
    if (String.IsNullOrEmpty(catID)) 
    { 
     var _product = from a in DataContext.GetProductsByDep(Convert.ToInt32(depID)) 
     select new { ID = a.ID, ProName = a.Name }; 
     jr.Data = _product.ToList();  
    } else { 
     var _product = from a in 
     DataContext.GetProductsByCat(Convert.ToInt32(depID),Convert.ToInt32(catID)) 
     select new { ID = a.ID, ProName = a.Name }; 
     jr.Data = _product.ToList();  
    } 
    return jr; 
} 

Answer 4

默認參數可從4.0版本。此外，閱讀這篇文章從MS http://blogs.msdn.com/b/csharpfaq/archive/2004/03/07/85556.aspx

Answer 5

你可以嘗試這樣的：

public JsonResult GetProductsByDepList(string depID) 
    { 
     return GetProductByCatList(depID, null); 
    } 

    public JsonResult GetProductByCatList(string depID, string catID) 
    { 
     JsonResult jr = new JsonResult(); 
     var _product = null; 
     if (!string.IsNullOrEmpty(catID)) 
     { 
      _product = from a in 
       DataContext.GetProductsByCat(Convert.ToInt32(depID),Convert.ToInt32(catID)) 
       select new { ID = a.ID, ProName = a.Name }; 
     } 
     else 
     { 
      _product = from a in DataContext.GetProductsByDep(Convert.ToInt32(depID)) 
       select new { ID = a.ID, ProName = a.Name }; 
     } 

     jr.Data = _product.ToList(); 
     jr.JsonRequestBehavior = JsonRequestBehavior.AllowGet; 
     return jr; 
    }