How to restrict deletions on Lookup field in SharePoint 2010

In this article we will be seeing how to restrict deletions on Lookup field in SharePoint 2010 using C# and power shell.

When you create a lookup column in SharePoint 2010 you can see "Relationship" where you can maintain referential integrity enforcing the relationships defined by lookup columns. Just like foreign key constraints in a relational database, in SharePoint 2010 you can configure restrict delete and cascade delete rules on lookup column relationships:

• Cascade delete rules: Delete items that reference a record when you delete that record.

• Restrict delete rules: Will prevent you from deleting a record that is referenced by a lookup column in another list.

Using C#:

a. Open Visual Studio 2010.

b. Create Console Application.

c. Replace the code with the following.

1. using System;

2. using System.Collections.Generic;

3. using System.Linq;

4. using System.Text;

5. using Microsoft.SharePoint;

6. namespace RestrictDeletions

7. {

8. class Program   

9. {

10. static void Main(string[] args)       

11. {

12. using (SPSite site = new SPSite("http://serverName:1111/SitePages/Home.aspx"))           

13. {

14. using (SPWeb web = site.RootWeb)               

15. {

16. SPList list = web.Lists.TryGetList("ChildList");

17. SPField field=list.Fields["Department"];

18. SPFieldLookup fieldLookup = (SPFieldLookup)field;                   

19. fieldLookup.Indexed = true;                   

20. fieldLookup.RelationshipDeleteBehavior = SPRelationshipDeleteBehavior.Cascade;                   

21. fieldLookup.Update();               

22. }           

23. }       

24. }   

25. }

26. }

d. Hit F5.

Using PowerShell:

1. $siteURL="http://serverName:1111/"

2. $site=Get-SPSite $siteURL

3. $web=$site.Rootweb

4. $list=$web.Lists.TryGetList("ChildList")

5. $field=$list.Fields["Department"]

6. $fieldLookup=[Microsoft.SharePoint.SPFieldLookup]$field

7. $fieldLookup.Indexed=$true

8. $fieldLookup.RelationshipDeleteBehavior [Microsoft.SharePoint.SPRelationshipDeleteBehavior]::Cascade

9. $fieldLookup.Update()