In this article we will be seeing how to configure key filters in SharePoint 
2010 using C#.
Key Filters appear just below the navigation hierarchy. Refer this Article 
to configure navigation hierarchy. Key Filters operate similar to the navigation 
hierarchy. They are used to filter the view of lists / document libraries.
The following fields are available for key filter fields are
- Content Type
- Choice Field
- Managed Metadata Field
- Person or Group Field
- Date and time field
- Number Field
I have a list and I am having the following 
items.
![KeyFilter1.gif]()
I am going to add the fields to the Key Filter Field using #
Steps Involved:
- Open Visual Studio 2010. 
- Create Console application. 
- Replace the code with the following.
 
 using 
	System;
 using 
	System.Collections.Generic;
 using 
	System.Linq;
 using 
	System.Text;
 using 
	Microsoft.SharePoint;
 using 
	Microsoft.Office.DocumentManagement.MetadataNavigation;
	
	namespace 
	ConfigureKeyFilter
 {
 class 
	Program
 {
 static void 
	Main(string[] args)
 {
 using (SPSite 
	site = new 
	SPSite("http://serverName:1111/"))
 {
 using (SPWeb 
	web = site.RootWeb)
 {
 SPList list=web.Lists.TryGetList("cl");
 SPField field=list.Fields["Country"];
 MetadataNavigationSettings 
	listNavSettings = MetadataNavigationSettings.GetMetadataNavigationSettings(list
 ;
 MetadataNavigationKeyFilter 
	mdnKeyFilter=new 
	MetadataNavigationKeyFilter (field);
 listNavSettings.AddConfiguredKeyFilter(mdnKeyFilter);
 MetadataNavigationSettings.SetMetadataNavigationSettings(list, 
	listNavSettings, true);
 }
 }
 }
 }
 }
 
 
- Hit F5.
Go to the List => List Settings =>General 
Settings =>Metadata navigation settings => Configure navigation hierarchies.
![KeyFilter2.gif]()
I have added "Country" field to the key filter field as shown in the following.
![KeyFilter3.gif]()
Click on Ok.
You could see the Key Filters in the left hand pane of the user interface.
![KeyFilter4.gif]()
Select some value from the key field and click on "Apply". You could see the 
view has been changed for the list based on the key field value.
![KeyFilter5.gif]()