Modify an existing item based on ID

Question

The following code is what is I use to insert new list items:

 using (SPSite oSPsite  = SPContext.Current.Site)
 ' using (SPWeb oSPWeb = oSPsite.OpenWeb())
 ' 
 SPList list = oSPWeb.Lists["SampleList"];

 SPListItem itemToAdd = list.Items.Add();
 itemToAdd["Title"] = TextBox1.Text;
 itemToAdd.Update();

How do I do "itemToAdd["Title"] = TextBox1.Text", by modifying an existing item where ID=4 rather than add a new item?

Answer 1

I was going to edit Mike's more, but here's a cleaner answer instead (sorry Mike!):

Basically there is no reason to make a new spsite object, also you should never really call .items (like ever, it will go get the entire list), and you don't need to call dispose on a spsite.Rootweb...

Anywhere here you go:

SPWeb oSPWeb = SPContext.Current.Site.RootWeb;
SPList list = oSPWeb.Lists["SampleList"];
SPListItem ItemToModify = list.GetItemById(4);
ItemToModify["Title"] = TextBox1.Text;
ItemToModify.Update();

As a side comment, since I don't have enough rep over here to comment on the question post: It isn't a good idea to do list.items.add() (MSOCAF may actually even error on this, don't remember), as calling .items will pull the entire list. Do this instead: http://sharepointdevsolutions.blogspot.com/2010/02/adding-items-to-large-lists.html

Answer 2

To modify the title of an item in your list with an ID of 4, do the following:

using (oSPSite = new SPSite(SPContext.Current.Site.URL))
{
     SPWeb oSPWeb = oSPSite.RootWeb;
     SPList list = oSPWeb.Lists["SampleList"];
     SPListItem ItemToModify = list.Items.GetItemById(4);
     ItemToModify["Title"] = TextBox1.Text;
     ItemToModify.Update();

}

And another thing: NEVER put a site out of SPContext into a "using" statement - that will dispose of the current context and will cause a lot of heartache in the future. If you insist on having your own SPSite object instead of just utilising the context, create a new SPSite object like I have above.