Deleting item from Sharepoint calendar

Question

I want to delete an item from sharepoint calendar. Here is part of my code:

                Microsoft.SharePoint.Client.CamlQuery query = new Microsoft.SharePoint.Client.CamlQuery();
                query.ViewXml = "<View><Query><Where><And><Eq><FieldRef Name='Title'/><Value Type='Text'>" 
                    + requestTitle +
                    "</Value></Eq><Eq><FieldRef Name='EventDate'/><Value Type='Text'>"
                    + lFrom +
                    "</Value></Eq></And><And><Eq><FieldRef Name='EndDate'/><Value Type='Text'>"
                    + lTo +
                    "</Value></Eq><Eq><FieldRef Name='fAllDayEvent'/><Value Type='Text'>"
                    + Boolean.TrueString +
                    "</Value></Eq></And></Where></Query></View>";

                Microsoft.SharePoint.Client.ListItemCollection listItem = calendar.GetItems(query);
                context.Load(listItem);
                if (listItem.Count == 1)
                {
                    listItem[0].DeleteObject();
                    //context.ExecuteQuery();
                }

It throws an exception in line

               if (listItem.Count == 1)

it says that listItem is not initialized. It even throws the exception when I pass empty query like this:

               Microsoft.SharePoint.Client.ListItemCollection listItem = calendar.GetItems(new Microsoft.SharePoint.Client.CamlQuery());

Why? On this link https://msdn.microsoft.com/en-us/library/office/ee534956(v=office.14).aspx it is said that it should retrieve all items when empty query is passed.

Evertyhing works perfectly for adding new item to calendar, here is code I used for that:

                //adding new calendar item
                Microsoft.SharePoint.Client.ListItemCreationInformation item = new Microsoft.SharePoint.Client.ListItemCreationInformation();
                Microsoft.SharePoint.Client.ListItem newItem = calendar.AddItem(item);
                newItem["Title"] = requestTitle;
                newItem["EventDate"] = lFrom;
                newItem["EndDate"] = lTo;
                newItem["fAllDayEvent"] = Boolean.TrueString;
                newItem.Update();

Piyush Piyush · Accepted Answer · 2015-08-03T09:35:49

Since, you have used,

Microsoft.SharePoint.Client

library, I am assuming its a client-side application. In client-side app, sending a request to the server is a costly affair. Hence, what actually happens is that whenever you load any component, only a request is created in the background. This way, you can bundle multiple request into 1 using the load() as many times. To actually send the request to the server, you need to call the ExecuteQuery() before checking the length of the listItemCollection.

Microsoft.SharePoint.Client.ListItemCollection listItem = calendar.GetItems(query);
context.Load(listItem);

context.ExecuteQuery(); // This will take a while

if (listItem.Count == 1)
{
    listItem[0].DeleteObject();
    context.ExecuteQuery();
}

Deleting item from Sharepoint calendar

1 Answers