ASP.NET列表框所选项目更改文本框文本

Question

So I got a listbox with 5 different persons in it. And when I click on the first person in the list a text appears in a textbox. An if I click on another person, we get another text in the textbox etc.

Here is my list:

private List<string> personsList = new List<string>();

personsList.Add("Person1");
personsList.Add("Person2");
personsList.Add("Person3");
personsList.Add("Person4");
personsList.Add("Person5");

ListBoxPersons.DataSource = personsList;
ListBoxPersons.DataBind();

So, if I click of Person1 we get the text "Andersson" in the textbox. If we click on Person2 we get the text "Smith" in the textbox.

I've tried this:

foreach (ListItem item in ListBoxPersons.Items)
{
    if (item.Text == "Person1")
    {
        TextBoxPersons.Text = "Andersson";
    }
    else if (item.Text == "Person2")
    {
        TextBoxPersons.Text = "Smith";
    }
}

And so on, but that didn't work. I have tried quite a few other ways of doing it, but sadly no luck with that either. This may seem silly, but it is just an exercise.

C# or JQuery works for me. Thanks in advance.

Answer 1

Your current code isn't checking what's currently selected, just each item in the list. You need to create a SelectedIndexChanged event to handle when you select something different. Something like this example on MSDN .

Basically, add the event to your asp.net ListBox control and then create the event in your code behind with the same name something like this:

private void ListBox1_SelectedIndexChanged(object sender, System.EventArgs e)
{
   // Get the currently selected item in the ListBox. 
   string curItem = listBox1.SelectedItem.ToString();

   switch(curItem)
   {
       case "Person1":
           TextBoxPersons.Text = "Andersson";
       break;
       case "Person2":
           TextBoxPersons.Text = "Smith";
       break;
       //Add more cases and perhaps a default...
   }
}

UPDATE

Just saw the comments from @Banana and @PhilipB. As mentioned you need to ensure you wrap the listbox initialization in if(!IsPostback) in your Page_Load event to ensure you don't lose the fact you've selected an item.

Answer 2

The above code which @sr28 suggested works fine I have tried it. This is the view:

<asp:ListBox ID="ListBox1" runat="server" AutoPostBack="true" 
                    onselectedindexchanged="ListBox1_SelectedIndexChanged">   </asp:ListBox>
                <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>`

on pageload bind the listbox:
           `if (!IsPostBack)
          {
            personsList.Add("Person1");
            personsList.Add("Person2");
            personsList.Add("Person3");
            personsList.Add("Person4");
            personsList.Add("Person5");
            ListBox1.DataSource = personsList;
            ListBox1.DataBind();   
}`

And this on the onSelectedIndexChanged:

protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e)
 {
        string curItem = ListBox1.SelectedItem.ToString();
        switch (curItem)
        {
            case "Person1":
                TextBox1.Text = "Andersson";
                break;
            case "Person2":
                TextBox1.Text = "Smith";
                break;
        }
  }

Answer 3

Code Behind

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            Dictionary<string, string> personsList = new Dictionary<string, string>();

            personsList.Add("Andersson", "Person1");
            personsList.Add("Smith", "Person2");
            personsList.Add("Name 3", "Person3");
            personsList.Add("Name 4", "Person4");
            personsList.Add("Name 5", "Person5");

            ListBoxPersons.DataTextField = "Value";
            ListBoxPersons.DataValueField = "Key";
            ListBoxPersons.DataSource = personsList;
            ListBoxPersons.DataBind();
        }
    }

    protected void ListBoxPersons_SelectedIndexChanged(object sender, EventArgs e)
    {
        TextBox1.Text = ListBoxPersons.SelectedValue;
    }

Page

    <asp:ListBox ID="ListBoxPersons" runat="server" OnSelectedIndexChanged="ListBoxPersons_SelectedIndexChanged" AutoPostBack="true"></asp:ListBox>
    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>