How to insert item to combobox after binding wpf

Question

I want to add an item to the combobox after binding it. for example:

this.cbCategory.ItemsSource = categoryList; this.cbCategory.DisplayMemberPath = "CategoryName"; this.cbCategory.SelectedValuePath = "CategoryID";

i want to add("All", "%") as the first one.

Geetha.

Ray Burns · Accepted Answer · 2010-07-16 08:26:56Z

This is very simple using a CompositeCollection:

<ComboBox DisplayMemberPath="CategoryName" SelectedValuePath="CategoryID"> <ComboBox.ItemsSource> <CompositeCollection> <my:Item CategoryName="All" CategoryID="%" /> <CollectionContainer Collection="{Binding CategoryList}" /> </CompositeCollection> </ComboBox.ItemsSource> </ComboBox>

How it works: The CompositeCollection produes the "All" item followed by all of the items in the CategoryList collection. Note that <my:Item ... /> is the constructor for your item class. You will need to change it to your actual namespace and class name.

Important advice: I notice you are setting some ComboBox properties in code-behind. This is a very bad practice. You should use XAML as shown above.

Hi, I am using the class which is present in the other project of the same solution. public class Category { /// <summary> /// Gets or sets the category ID. /// </summary> /// <value>The category ID.</value> public string CategoryID { get; set; } /// <summary> /// Gets or sets the name of the category. /// </summary> /// <value>The name of the category.</value> public string CategoryName { get; set; } } Then how i have to call this.
You can reference any class by setting an appropriate XML namespace. For example, xmlns:otherProject="clr-namespace:NamespaceInOtherProject;assembly=OtherAssembly". Then instead of <my:Item ...> you write <otherProject:Item ...>.

Goblin · Accepted Answer · 2010-07-16 07:33:53Z

You'll break the binding if you try to add it later and will no longer receive updates.

Why not just add your 'extra' item before you bind it?

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