如何通过Arraylist进行迭代 [英] how to iterate through through Arraylist

问题描述

我的WebMethod会像这样返回arraylist：

 [WebMethod] 
  public   static  ArrayList ProcessIT（ string  strpid ）
 {
 DataTable dt =  new  DataTable（）; 
 ArrayList list =  new  ArrayList（）; 
  string  queryString =   select * from Registration其中RegNo =' + strpid +  '和Deleted = 1; 
 使用（SqlConnection con =  new  SqlConnection（   Server = op- maurya; Database = DishaEyeHospitals; User ID = sa; Password = Password123; Trusted_Connection = False;））
 { 
 使用（SqlCommand cmd =  new  SqlCommand（queryString，con））
 { 
 con.Open（）; 
 SqlDataAdapter adp =  new  SqlDataAdapter（cmd）; 
 adp.Fill（dt）; 
  foreach （DataRow dr  in  dt.Rows）
 {
 list.Add（DR）; 
} 
} 
} 
  return  list; 
} 
它工作正常，但我想在 javascript $中迭代此列表 b $ b < script  >  
 function getpid（）
 {
  var  _pid = document.getElementById（' < ;％= txtpid.ClientID％>'）。 value ; 
 alert（_pid）; 
 
 PageMethods.ProcessIT（_pid，onSucess，onError）; 
函数onSucess（结果）
 {
  for （ var  i  结果）
 {
 alert（response [i]）; 
} 
 返回  true ; 
} 
函数onError（结果）
 {
 alert（ 错误）; 
  for （ var  i  in 结果）
 {
 alert（response [i]）; 
} 
 
 返回  false ; 
} 
} 
 < /   script  >  

解决方案

这看起来像C＃，而不是JavaScript。 :-)



如果是这样，你永远不应该使用 ArrayList 。早在第2版引入泛型时，这种类型就已经过时了。形式上，该类没有标记 [Obsolete] 属性，因为将它留在某些遗留代码中没有任何问题，但在新开发中它从未有任何意义。改为使用 System.Collections.Generic.List<> 。



迭代完全按照你的方式完成与您的数据行：

 System.Collections.Generic.List< SomeType> list =  new  System.Collections.Generic.List< SomeType>（）; 
  //   ...  
  foreach （SomeType item  in  list）{ / *   ... * / } 

此代码可以通过类型推断缩短：

  var  list =  new  System.Collections.Generic.List< SOMETYPE>（）; 
  //   ...  
  foreach （ var  item  in  list）{ / *   ... * / } 

-SA

Hi,
My WebMethod returns arraylist like this:

 [WebMethod]
    public static ArrayList ProcessIT(string strpid)
    {
      DataTable dt = new DataTable();
      ArrayList list = new ArrayList();
      string queryString = "select * from Registration where RegNo='"+strpid+"' and Deleted=1";
      using (SqlConnection con = new SqlConnection("Server=op- maurya;Database=DishaEyeHospitals;User ID=sa;Password=Password123;Trusted_Connection=False;"))
        {
            using(SqlCommand cmd = new SqlCommand(queryString, con))
             {
                con.Open();
                SqlDataAdapter adp = new SqlDataAdapter(cmd);
                adp.Fill(dt);
                foreach(DataRow dr in dt.Rows)
                    {
                        list.Add(dr);
                    }
              }       
        }
        return list;
    }
it work fine but i want to iterate this list in javascript
<script>
function getpid()
{
var _pid=document.getElementById('<%=txtpid.ClientID %>').value;
alert(_pid);

PageMethods.ProcessIT(_pid,onSucess,onError);
function onSucess(result) 
{
    for (var i in result) 
     {
       alert(response[i]);
     }
     return true;
}
function onError(result) 
{
    alert("Error");
  for (var i in result) 
     {
       alert(response[i]);
     }
     
     return false;
}
}   
</script>

解决方案

This looks like C#, not JavaScript. :-)

If so, you should never use ArrayList. This type was rendered obsolete as early as by v.2.0, when generics were introduced. Formally, the class wasn't marked with [Obsolete] attribute only because there is nothing wrong with leaving it in some legacy code, but in new development it never makes any sense. Use System.Collections.Generic.List<> instead.

The iteration is done exactly as you did with your data rows:

System.Collections.Generic.List<SomeType> list = new System.Collections.Generic.List<SomeType>();
//...
foreach (SomeType item in list) { /* ... */ }

This code can be shortened with type inference:

var list = new System.Collections.Generic.List<SomeType>();
//...
foreach (var item in list) { /* ... */ }

—SA

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