Hello,

I have two TreeNodeDatasets A an B. They may have some common TreeNodes, but may not.

I wish to exclude elements of B which are found in A, from set A.

Code:

var pinnedArticles = TreeHelper.GetDocuments(CMSContext.CurrentSiteName, "/Articles/Pinned-Articles/%",
											 CMSContext.PreferredCultureCode, false, "custom.article", null,
											 null, 1, true, 5);

var taggedArticles = TreeHelper.GetDocuments(CMSContext.CurrentSiteName, "/Articles/%",
											 CMSContext.PreferredCultureCode, false, "custom.article",
											 whereCondition, null, 5, true, 5);

if (pinnedArticles != null)
{
	foreach (var article in pinnedArticles)
	{
		article.NodeCustomData.Value = "isPinned";
		if (taggedArticles.Any(m => m.DocumentGUID == article.DocumentGUID))
		{
			var articleToRemove = taggedArticles.First(m => m.DocumentGUID == article.DocumentGUID);
			taggedArticles.Items.Remove(articleToRemove);

		}
	}

I get a NullReferenceException on the highlighted line. Inspecting the code, however, shows that "articleToRemove" is not null.

Any assistance would be appreciated.