Update listitem problem

Question

i am trying to update a listitem in a event receiver on FeatureActivated in a document library.

 public override void FeatureActivated(SPFeatureReceiverProperties properties)
    {

        SPSecurity.RunWithElevatedPrivileges(delegate()
        {
            using (SPSite site = SPContext.Current.Site)
            {
                using (SPWeb myweb = site.OpenWeb())
                {


                SPList list = myweb.Lists.TryGetList("Document Library");
                SPListItemCollection items = list.GetItems();

                for (int i = 0; i < items.Count; i++)
                {

                    SPListItem item = items[i];



                    Guid fieldID = item.Fields.GetFieldByInternalName("Age").Id;

                    string valueField = item[fieldID].ToString();
                    valueField = "";
                    item.Update();
                }
                }
            }
        });            
    }

My field does not get empty?

Answer 1

Because you do not Change the value in the field, you just Change the value in your variable.

you have to

item[fieldID] = "";

Answer 2

Avoid using SPContext inside receiver. SPContext doesn't exist in a feature receiver. Instead use the Properties object as it includes a reference to the site or web

use following

 public override void FeatureActivated(SPFeatureReceiverProperties properties)
    {
        SPWeb web = properties.Feature.Parent as SPWeb;
        using (SPSite site = new SPSite(web.Site.ID))
        {
            using (SPWeb rootWeb = site.OpenWeb(site.RootWeb.ID))
            {
                SPSecurity.RunWithElevatedPrivileges(delegate
                {
                    //Your code
                });
            }
        }
    }

Answer 3

Try

public override void FeatureActivated(SPFeatureReceiverProperties properties)
{

    SPSecurity.RunWithElevatedPrivileges(delegate()
    {
        using (SPSite site = SPContext.Current.Site)
        {
            using (SPWeb myweb = site.OpenWeb())
            {


            SPList list = myweb.Lists.TryGetList("Document Library");
            SPListItemCollection items = list.GetItems();

            for (int i = 0; i < items.Count; i++)
            {

                SPListItem item = items[i];
                item["Age"] = string.Empty
                item.Update();
            }
            }
        }
    });            
}