SharePoint Webpart display two times in aspx page

Question

Recently to organize a document library I opened it in Windows Explorer mode to drag and drop files. I do this frequently. I think I was moving too fast and inadvertently clicked something by mistake. A dialog box popped up asking about hiding Webparts. I think I clicked Yes. I accidently hid the document library Webpart. So I went in to Re-Add the WebPart to my page. But now the Webpart appears twice on my page. Only 1 Webpart is added but two show up. I removed the WebPart I added and closed the editor. The document library still shows up even with no WebParts on the page! This phantom library/webpart does not have a full menu bar or a View drop down and I am unable to add them because there is no WebPart associated with the library to go in and modify! I need a full menu bar - otherwise I would leave it as-is. I re-added the document library WebPart again and when I close out not only do I see the two webparts but the Quick Launch shows two links with the same name! I have to ask it to hide the link on the WebPart I have access to so only one link will appear.

Ramesh Palaniappan · Answer

First of all you're doing the number one mistake when building Web Parts (or ASP.NET controls for that matter). Never ever write code like this in the Render() method. Use the CreateChildControls() preferrably (IMHO) and if that not suits you use RenderContents(). If you're using/overriding the Render() you can break all kinds of things. Then; never ever iterate over all list items using SPList.Items it's just bad and will kill performance. Use SPQuery and the GetItems() method to retrieve only the items and columns you need. Then; why are you creating new SPSite and SPWeb objects? They are already there in SPContext.Current.Site and SPContext.Current.Web. Then; you're trying to write a ul tag with runat=server - that won't work. It will only be an invalid attribute in the resulting HTML Then; since your concatenating strings I suggest you're looking into the StringBuilder class. For each string operation you're doing you're just allocating new stuff on the heap Then; if you're writing code for SP2010 use the SPWeb.Lists.TryGetList() that will save you some exception handling Just a few pointers on your way to building the perfect Web Part!