Pass by value - List name

Question

Can someone tell me what I am doing wrong here? I trying to pass the list name to a method that would delete all the rows in the list:

    public static void DeleteLastUpdate(Microsoft.SharePoint.Client.List oList)
    {
        using (var context = new ClientContext(FrontEndAppUrl))
        {
            var ss = new System.Security.SecureString();
            Array.ForEach("hhh".ToCharArray(), (c) => { ss.AppendChar(c); });
            context.Credentials = new SharePointOnlineCredentials("yyy", ss);
            var web = context.Web;

            ListItemCreationInformation itemCreateInfo = new ListItemCreationInformation();

            CamlQuery camlQuery = new CamlQuery();
            camlQuery.ViewXml = "<View><Query><OrderBy><FieldRef Name='ID' Ascending='TRUE' /></OrderBy></Query></View>";
            ListItemCollection collListItem = oList.GetItems(camlQuery);
            context.Load(collListItem);

            context.ExecuteQuery();



            foreach (ListItem oListItem in collListItem)
            {

                string i = oListItem["ID"].ToString(); ;

                ListItem ListItemToDelete = oList.GetItemById(i);

                ListItemToDelete.DeleteObject();

                context.ExecuteQuery();

            }

            oList.Update();
        }

    }

    public static void GetCountry()
    {
        using (var context = new ClientContext(FrontEndAppUrl))
        {
            Microsoft.SharePoint.Client.List oList_Country = context.Web.Lists.GetByTitle("LISTNAME");

            DeleteLastUpdate(oList_Country);


        }

    }

The error I am getting is at context.Load(collListItem);

It says The object is used in the context different from the one associated with the object. How else can I pass the value of the list to the Delete() method?

Answer 1

Exactly what the exception says is what is happening. You create the oList_Country in the context of GetCountry() and then pass it to DeleteLastUpdate() where you are working within a different context.

Maybe you should think about passing the context to DeleteLastUpdate() via a parameter. Then your code would become something like this:

public static void DeleteLastUpdate(ClientContext context, Microsoft.SharePoint.Client.List oList)
{
    // You should not create a context here, but use the supplied context
    // using (var context = new ClientContext(FrontEndAppUrl))
    // {
        var ss = new System.Security.SecureString();
        ...
}

public static void GetCountry()
{
    using (var context = new ClientContext(FrontEndAppUrl))
    {
        Microsoft.SharePoint.Client.List oList_Country = context.Web.Lists.GetByTitle("LISTNAME");

        DeleteLastUpdate(context, oList_Country);  // Pass the context