如何添加“选择项目”到使用LINQ to SQL填充的下拉列表？ [英] How do I add a "Select item" to a drop down list that has been filled using LINQ to SQL?

问题描述

我有一个下拉列表，我使用linq填充sql，它将显示美国州的列表。在下拉列表的顶部，我想要一个值为XX的选择状态条目。这是我第一次真正使用linq来sql我有点迷失。



这是我的代码到目前为止：

< pre lang =c＃> var theStates = 来自州 in db.States
选择 new
{
StateID = states.StateID，
StateName = states.StateName
};


dropPrimaryAddressState.DataSource = theStates;
dropPrimaryAddressState.DataTextField = StateName;
dropPrimaryAddressState.DataValueField = StateID;
dropPrimaryAddressState.DataBind（）;

解决方案

  var  theStates = 来自状态 in  db.States 
 选择  new  
 {
 StateID = states.StateID，
 StateName = states。 StateName 
}; 
 
 dropPrimaryAddressState.DataSource = theStates; 
 dropPrimaryAddressState.DataTextField =   StateName; 
 dropPrimaryAddressState.DataValueField =   StateID; 
 dropPrimaryAddressState.DataBind（）; 
 
 ListItem newItem =  new  ListItem（）; 
 newItem.Text =  选择状态; 
 newItem.Value =   XX; 
 
 dropPrimaryAddressState.Items.Insert（ 0 ，newItem）; 
 
 dropPrimaryAddressState.SelectedIndex =  0 ; 

I have a drop down list that I am filling using linq to sql which will display a list of U.S. states. At the top of the drop down I would like to have a "Select a State" entry with a value of "XX". This being the first time I have really used linq to sql I am a little lost.

Here is my code so far:

var theStates = from states in db.States
                                select new
                                {
                                    StateID = states.StateID,
                                    StateName = states.StateName
                                };

                
                dropPrimaryAddressState.DataSource = theStates;
                dropPrimaryAddressState.DataTextField = "StateName";
                dropPrimaryAddressState.DataValueField = "StateID";
                dropPrimaryAddressState.DataBind();

解决方案

var theStates = from states in db.States
                                select new
                                {
                                    StateID = states.StateID,
                                    StateName = states.StateName
                                };

dropPrimaryAddressState.DataSource = theStates;
dropPrimaryAddressState.DataTextField = "StateName";
dropPrimaryAddressState.DataValueField = "StateID";
dropPrimaryAddressState.DataBind();

ListItem newItem = new ListItem();
newItem.Text = "Select a State";
newItem.Value = "XX";

dropPrimaryAddressState.Items.Insert(0, newItem);

dropPrimaryAddressState.SelectedIndex = 0;

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