Checks if item field link exists into a custom list

Question

Hi;
I have a custom list with 2 columns : Title and SITE (field link)
Title (text) : 
SITE (link) :   URL + DESCRIPTION
I would like to write in programmming a code which allows to checks before to add a new item if this item exists or not into the list in using only the DESCRIPTION or URL field.
Like this :
if(DESCRIPTION !exists)
{   add item }
else{ show message : the site exists }
Regards 

Answer 1

Hi,
We can use event receiver to achieve your requirement. The following code for your reference:
using System;
using System.Security.Permissions;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Utilities;
using Microsoft.SharePoint.Workflow;
namespace SharePointProject5.EventReceiver1
/// <summary>
/// List Item Events
/// </summary>
public class EventReceiver1 : SPItemEventReceiver
/// <summary>
/// An item is being added.
/// </summary>
public override void ItemAdding(SPItemEventProperties properties)
base.ItemAdding(properties);
if(properties.AfterProperties["SITE"]!=null)
string linkField=properties.AfterProperties["SITE"].ToString();
string urlValue = linkField.Split(',')[0];
if (CheckItemExists(properties.List, null, urlValue))
properties.Status = SPEventReceiverStatus.CancelWithError;
properties.ErrorMessage = "The site exists.";
private bool CheckItemExists(SPList list, SPFolder folder, string urlValue)
SPQuery query = new SPQuery();
if (folder != null)
query.Folder = folder;
query.Query = @"
<Where>
<Eq>
<FieldRef Name='SITE' />
<Value Type='Text'>" + urlValue + @"</Value>
</Eq>
</Where>";
SPListItemCollection found = list.GetItems(query);
return (found.Count > 0);
Best Regards
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