Get Value of QueryString from SharePoint Event Receiver

Hello Friends

From SharePoint Event Receivers how could we get the value which has been passed from querystring? 

How can we achieve this? Here is the sample of code.

public class AddData: SPItemEventReceiver

    {

        System.Web.HttpContext httpContext = null;

        /// <summary>

        /// An item was added.

        /// </summary>

        public AddData ():base()

         {

                 //get the httpContext in contsructor, we won't get

                 //this outside of this constructor

             try

             {

                 httpContext = System.Web.HttpContext.Current;

             }

             catch (Exception Ex)

             {

             }

        }

public override void ItemAdding(SPItemEventProperties properties)

        {

                if (httpContext != null)

                {

                    if (httpContext.Request.QueryString["Data"] != null)

                    {

                                                String strData= httpContext.Request.QueryString["Data "].ToString();

}

                }

            }

}

Enjoy coding!!!

Disha Shah

How to access fields of List Item in ItemAdding and ItemUpdating event handlers into SharePoint

When we need to validate something or put restriction before adding or modifying data, at that time we need to use ItemAdding or ItemUpdating Event Handler, here I’ll demonstrate how to access fields of List into event handlers.

Example:

As per my requirements, I don’t want to add duplicate Name into List. For this I need to check that condition before I add and update item to List, I need to use “ItemAdding” and “ItemUpdating” event handlers

public override void ItemAdding(SPItemEventProperties properties)
{
string strName = string.Empty;

foreach (DictionaryEntry entry in properties.AfterProperties)
{
if (entry.Key.Equals("Name"))
{
strName = entry.Value.ToString();
}
}

SPList list = properties.OpenWeb().Lists[properties.ListId];
SPQuery query = new SPQuery();
query.Query = "<Where><Eq><FieldRef Name='" + list.Fields["Name"].InternalName + "' /><Value Type='Text'>" + strName + "</Value></Eq></Where>";
if (list.GetItems(query).Count > 0)
{
properties.Cancel = true;
properties.ErrorMessage ="Name already exists!";
}
}
public override void ItemUpdating(SPItemEventProperties properties)
{
string strName = string.Empty;
foreach (DictionaryEntry entry in properties.AfterProperties)
{
if (entry.Key.Equals("Name"))
{
strName = entry.Value.ToString();
}
}
SPList list = properties.OpenWeb().Lists[properties.ListId];
SPQuery query = new SPQuery();
query.Query=  "<Where><And><Neq><FieldRef Name='"+ list.Fields["ID"].InternalName+ "' /><Value Type='Number'>"+ properties.ListItemId+  "</Value></Neq><Eq><FieldRef Name='"+ list.Fields["Name"].InternalName+ "' /><Value Type='Text'>"+ strName+ "</Value></Eq></And></Where>" ;
if (list.GetItems(query).Count > 0)
{
properties.Cancel=true;
properties.ErrorMessage ="Name already exists!";
}
}