Modify quick navigation using c# CSOM

Question

I am using the below code. While debugging I always get the error :

"Collection not initialised"

in line 3

private static void GenerateLeftNav(ClientContext cltContext, string webUrl)
        {
            cltContext.Load(cltContext.Web);
            cltContext.ExecuteQuery();
            NavigationNodeCollection qlNavNodeColl = cltContext.Web.Navigation.QuickLaunch;
            cltContext.Load(qlNavNodeColl);
            //Fetching node which needs to be updated

            //   IEnumerable<NavigationNode> projectsNode = cltContext.LoadQuery(qlNavNodeColl.Where(n => n.Title == "Projects"));
            NavigationNode projectsNode = qlNavNodeColl.Where(n => n.Title == "Projects").FirstOrDefault();
            if (projectsNode != null)
            {
                try
                {
                    NavigationNode gNode = projectsNode;
                    gNode.Url = webUrl;
                    gNode.Update();
                    cltContext.ExecuteQuery();
                }
                catch (Exception)
                {
                    throw;
                }
            }

    }

Answer 1

You are missing the executeQuery after loading the quick launch navigation node collection.

Modify the code as below:

cltContext.Load(cltContext.Web);
cltContext.ExecuteQuery();
NavigationNodeCollection qlNavNodeColl = cltContext.Web.Navigation.QuickLaunch;
cltContext.Load(qlNavNodeColl);
//add the execute query method
cltContext.ExecuteQuery();

Answer 2

I tried your code at my end. Everything is correct except one line.

Remove cltContext.ExecuteQuery(); from second line and just keep cltContext.ExecuteQuery(); after cltContext.Load(qlNavNodeColl);.

So your final code will be like

private static void GenerateLeftNav(ClientContext cltContext, string webUrl)
    {
        cltContext.Load(cltContext.Web);
        NavigationNodeCollection qlNavNodeColl =ltContext.Web.Navigation.QuickLaunch;
        cltContext.Load(qlNavNodeColl);
        cltContext.ExecuteQuery();
        NavigationNode projectsNode = qlNavNodeColl.Where(n => n.Title == "Projects").FirstOrDefault();
        if (projectsNode != null)
        {
             try
             {
                 NavigationNode gNode = projectsNode;
                 gNode.Url = webUrl;
                 gNode.Update();
                 cltContext.ExecuteQuery();
              }
              catch (Exception)
              {
                 throw;
              }
       }
    }