How do I update a Sharepoint ListItem with .Net?

Question

Basically I query Sharepoint and get a list of ListItems. I foreach through the list and check to see if the item needs to be updated from an external db (that code is not present)

Here is the bit of code that I was running that would not update the Sharepoint ListItem. I even tried different credentials to no avail.

using(ClientContext ctx = new ClientContext(searchsiteurl)) {
    //NetworkCredential credit = new NetworkCredential(prg.userName, prg.password, prg.domain);
    //ctx.Credentials = credit;
    Web web = ctx.Web;

    List list = web.Lists.GetById(new Guid(site.ListGUID));

    var q = new CamlQuery();
    if (Fullsync) {
        q.ViewXml = "<View><Query><Where><And><BeginsWith><FieldRef Name='SrNumber' /><Value Type='Text'>1</Value></BeginsWith>" + "<Eq><FieldRef Name='_ModerationStatus' /><Value Type='ModStat'>Draft</Value></Eq></And></Where></Query></View>";
    }
    else {

        q.ViewXml = "<View><Query><Where><And><Contains><FieldRef Name='SrNumber' /><Value Type='Text'>1-</Value></Contains><And>" + "<Eq><FieldRef Name='_ModerationStatus' /><Value Type='ModStat'>Approved</Value></Eq>" + "<Gt><FieldRef Name='Modified' /><Value IncludeTimeValue='TRUE' Type='DateTime'>" + last24hours + "</Value></Gt>" + "</And></And></Where></Query></View>";
    }

    var r = list.GetItems(q);
    ctx.Load(r);
    ctx.ExecuteQuery();
    foreach(SP.ListItem lit in r) {
        //do a whole bunch of stuff....

        // this does NOT WORK
        lit.FieldValues["Linked_x0020_CSRs"] = LinkedSRs;
        lit.Update();
        ctx.ExecuteQuery();

    }
}

Answer 1

The problem with the documentation is that it does not explicitly indicate that you must use the .GetItemById() function to retrieve a ListItem in order to update that ListItem.

So here is the code that should help out future people searching for this answer. It took me waaaay too long to figure this out.

                 using (ClientContext ctx = new ClientContext(searchsiteurl))
                {
                    //NetworkCredential credit = new NetworkCredential(prg.userName, prg.password, prg.domain);
                    //ctx.Credentials = credit;
                    Web web = ctx.Web;

                    List list = web.Lists.GetById(new Guid(site.ListGUID));


                   var q = new CamlQuery();
                    if (Fullsync)
                    {
                        q.ViewXml = "<View><Query><Where><And><BeginsWith><FieldRef Name='SrNumber' /><Value Type='Text'>1</Value></BeginsWith>" +
                            "<Eq><FieldRef Name='_ModerationStatus' /><Value Type='ModStat'>Draft</Value></Eq></And></Where></Query></View>";
                    }
                    else
                    {

                        q.ViewXml = "<View><Query><Where><And><Contains><FieldRef Name='SrNumber' /><Value Type='Text'>1-</Value></Contains><And>" +
                                "<Eq><FieldRef Name='_ModerationStatus' /><Value Type='ModStat'>Approved</Value></Eq>" +
                                "<Gt><FieldRef Name='Modified' /><Value IncludeTimeValue='TRUE' Type='DateTime'>" + last24hours + "</Value></Gt>" +
                                "</And></And></Where></Query></View>";
                    }


                    var r = list.GetItems(q);
                    ctx.Load(r);
                    ctx.ExecuteQuery();
                    foreach (SP.ListItem lit in r)
                    {
                                //do a whole bunch of stuff....


                                /* this does NOT WORK
                                lit.FieldValues["Linked_x0020_CSRs"] = LinkedSRs;
                                lit.Update();
                                ctx.ExecuteQuery();
                                */

                                // this works!
                                    var KAToModify = list.GetItemById(lit.Id);
                                    KAToModify["Linked_x0020_CSRs"] = LinkedSRs;
                                    KAToModify.Update();
                                    ctx.ExecuteQuery();

                    }
            }