How to copy items from one DropDownList to another

Question

How to copy elements with hard code from one drop-down list to another, keeping keys and values?

drpTypes.Items.Add(new ListItem("Tipos de Acções", "1")); drpTypes.Items.Add(new ListItem("Tipos de Combustível", "2")); drpTypes.Items.Add(new ListItem("Tipos de Condutor", "3")); drpTypesCreateEdit.Items.AddRange(drpTypes.Items); 

Answer 1

AddRange wants an array of ListItems. you can do it like this (C # 3+).

 drpTypesCreateEdit.Items.AddRange(drpTypes.Items.OfType<ListItem>().ToArray()); 

Answer 2

Agree with Anthony's comment above.

However, since the selected ListItems will still reference the same objects in the original DropDownList, there will be unintended side effects when changing fields / properties.

For example:

 drpTypes.Items.Add(new ListItem("Tipos de Acções", "1")); drpTypes.Items.Add(new ListItem("Tipos de Combustível", "2")); drpTypes.Items.Add(new ListItem("Tipos de Condutor", "3")); drpTypesCreateEdit.Items.AddRange(drpTypes.Items); drpTypes.SelectedValue = "2"; drpTypesCreateEdit.SelectedValue = "3"; 

Both drpTypes and drpTypesCreateEdit now have a SelectedValue of "3", while this is clearly not the purpose of the above code.

Creating new ListItem objects instead of simply selecting the source object will fix this:

 drpTypesCreateEdit.Items.AddRange(drpTypes.Items.Cast<ListItem>().Select(x => New ListItem(x.Text, x.SelectedValue)).ToArray(); 

Answer 3

That would be one of the easiest ways.

 drpTypes.Items.Add(new ListItem("Tipos de Acções", "1")); drpTypes.Items.Add(new ListItem("Tipos de Combustível", "2")); drpTypes.Items.Add(new ListItem("Tipos de Condutor", "3")); foreach(ListItem li in drpTypes.Items) { drpTypesCreateEdit.Items.Add(li); } 

Do you need something more complicated?

Answer 4

I could not figure it out in VB.NET, and it took me a while to find this answer. Duplicate DropDownListItems without Looping

 DropDownList2.DataSource = DropDownList1.Items DropDownList2.DataTextField = "Text" DropDownList2.DataValueField = "Value" DropDownList2.DataBind() 

This will make a deep copy between the two dropdownlists.

Perhaps the administrator can delete this answer and link the two questions together.

Answer 5

 This is also good for copying DropDownList items to another. 

Example: it will copy all the elements from DropDownList1 to DropDownList2.

Elements in DropDownList1:

 <asp:DropDownList ID="DropDownList1" runat="server"> <asp:ListItem Text="A" Value="1"></asp:ListItem> <asp:ListItem Text="B" Value="2"></asp:ListItem> <asp:ListItem Text="C" Value="3"></asp:ListItem> <asp:ListItem Text="D" Value="4"></asp:ListItem> <asp:ListItem Text="E" Value="5"></asp:ListItem> </asp:DropDownList> 

1 - First, copy DropDownList1 to the array.

 ListItem[] ListitemsArray = new ListItem[DropDownList1.Items.Count]; DropDownList1.Items.CopyTo(ListitemsArray, 0); 

2 - : now copy from the array to DropDownList2.

  foreach (ListItem liItems in ListitemsArray) { DropDownList2.Items.Add(liItems); } 

This works for me !!!!!!!!!!!!!

Answer 6

I did it right from one drop down to another, reducing the need to copy to the array first.

  foreach(ListItem listItem in myDropDownList.Items) { myOtherDropDownList.Items.Add(listItem) } 

Answer 7

I used this as

 comboBox2.Items.AddRange(comboBox3.Items.OfType<string>().ToArray()); 

Answer 8

in vb i use

 Dim cb As CheckBoxList=new CheckBoxList() cb.Items.AddRange(CheckBoxList_Source.Items.Cast(Of ListItem)().Select(Function(f) New ListItem(f.Text, f.Value)).ToArray()) 

or

 Dim cb As CheckBoxList=new CheckBoxList() cb.DataSource = CheckBoxList_Source.Items cb.DataBind() 

but this binds the value to the text instead of the true value of the original elements

this is the only way i discovered cloning elements