c# - C# 委托事件处理程序 SelectedIndexChanged

Question

我想将另一个值传递给 LeCmb_Statut_SelectedIndexChanged 方法，我该如何继续？

我有代码：

SqlDataReader reader = comm.ExecuteReader(); 
while (reader.Read())
{
   ...
   DropDownList LeCmb_Statut = new DropDownList();
   string tempLabel = reader["LIBELLE"].ToString();
   string templabelVeh = reader["LIBVEH"].ToString()
}

如何将这些临时变量传递给LeCmb_Statut_SelectedIndexChanged?

LeCmb_Statut.SelectedIndexChanged += new EventHandler(LeCmb_Statut_SelectedIndexChanged);

Answer 1

您可以使用下拉列表的 Tag 属性。首先，创建一个简单的 DTO：

public class LabelDTO
{
   public string Label {get;set;}
   public string LabelVeh {get;set;}
} 

然后：

while (reader.Read())
{
   ...
   DropDownList LeCmb_Statut = new DropDownList();
   LabelDTO lbl= new LabelDTO(){Label=reader["LIBELLE"].ToString(), LabelVeh=reader["LIBVEH"].ToString()};

    LeCmb_Statut.Tag=lbl;
}

然后在 LeCmb_Statut_SelectedIndexChanged 内：

LeCmb_Statut_SelectedIndexChanged (object sender, System.EventArgs e)
{
    LabelDTO labelDTO= ((DropDownList)sender).Tag as LabelDTO ;
    if (labelDTO!=null)
     {
        ///here you can use the label and labelVeh properties.

     }
}

Answer 2

您可以使用匿名方法来捕获它们：

string tempLabel = reader["LIBELLE"].ToString();
string templabelVeh = reader["LIBVEH"].ToString()
LeCmb_Statut.SelectedIndexChanged += delegate {
    // do something fun with   tempLabel  and templabelVeh 
};

对于小块或更长的代码，这可能是内联的 - 只需传递给一个方法：

string tempLabel = reader["LIBELLE"].ToString();
string templabelVeh = reader["LIBVEH"].ToString()
LeCmb_Statut.SelectedIndexChanged += delegate {
    DoSomethingFun(tempLabel,templabelVeh);
};

或者如果您需要发件人/参数：

string tempLabel = reader["LIBELLE"].ToString();
string templabelVeh = reader["LIBVEH"].ToString()
LeCmb_Statut.SelectedIndexChanged += delegate(object sender, EventArgs args) {
    DoSomethingFun(sender,args,tempLabel,templabelVeh);
};

或在 C# 3.0 中：

string tempLabel = reader["LIBELLE"].ToString();
string templabelVeh = reader["LIBVEH"].ToString()
LeCmb_Statut.SelectedIndexChanged += (sender, args) =>
    DoSomethingFun(sender,args,tempLabel,templabelVeh);