SharePoint Content Query Webpart - Auto CommonViewFields

gistfile1.cs

public class ContentDisplayWebPart : ContentByQueryWebPart
    {
        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);
            string headerlink = "/Style%20Library/XSL%20Style%20Sheets/CustomXsl/______.xsl";
            string itemlink = "/Style%20Library/XSL%20Style%20Sheets/CustomXsl/______.xsl";
            if (this.HeaderXslLink != headerlink) { this.HeaderXslLink = headerlink; }
            if (this.ItemXslLink != itemlink) { this.ItemXslLink = itemlink; }
            if (this.CommonViewFields != (string)HttpContext.Current.Cache[this.Title + "_CommonViewFields"])
            {
                Dictionary<string, string> CommonViewFieldsDictionary = new Dictionary<string, string>();
                if (!string.IsNullOrEmpty(this.ListGuid) && this.ListGuid != Guid.Empty.ToString())
                {
                    SPWeb web = SPContext.Current.Site.OpenWeb(this.WebUrl.Replace("~sitecollection", ""));
                    foreach (SPContentType ContentType in web.Lists[this.ListName].ContentTypes)
                    {
                        foreach (SPField field in ContentType.Fields)
                        {
                            if (!CommonViewFieldsDictionary.ContainsKey(field.InternalName))
                            {
                                CommonViewFieldsDictionary.Add(field.InternalName, field.TypeAsString);
                            }
                        }
                    }
                    foreach (SPField field in web.Lists[this.ListName].Fields)
                    {
                        if (!CommonViewFieldsDictionary.ContainsKey(field.InternalName))
                        {
                            CommonViewFieldsDictionary.Add(field.InternalName, field.TypeAsString);
                        }
                    }
                    CommonViewFieldsDictionary.ToList().ForEach(item =>
                    {
                        CommonViewFields += string.Format("{0},{1};", item.Key, item.Value);
                    });
                }
                HttpContext.Current.Cache.Add(this.Title + "_CommonViewFields", CommonViewFields, null, DateTime.Now.AddMinutes(15), Cache.NoSlidingExpiration, CacheItemPriority.Default, null);
            }
        }
    }