How to get display form URL of a list item

Often, developing custom web parts, you may want to render a link to a list item. In SharePoint 2.0 you could get a list in which a list item is stored, and just create a link pointing to its display form, providing ID of a list item as a parameter in request query string. In SharePoint 3.0 this task is a bit more complicated, because now developers can specify custom URL of edit/new/display forms for each content type. If custom URL is not specified, content type uses appropriate form of a list. To make things even more complicated, URL of a custom form can point to application pages (stored in _layouts) as well. In this case, you should pass not only ID of an item as a parameter in request query string, but also GUID of a list, in which this item is stored. Otherwise, application page can not determine in which list it should search for an item with specified ID. So, if you need to get a complete URL of item’s display form, you may code something like:

using Microsoft.SharePoint;
using Microsoft.SharePoint.Utilities;

SPListItem item = GetItem(); // some code to get a list item
SPList list = item.ParentList;
SPWeb web = list.ParentWeb;

string webUrl = web.Url;
string dispUrl = item.ContentType.DisplayFormUrl;
if(dispUrl == "")
dispUrl = list.Forms[PAGETYPE.PAGE_DISPLAYFORM].Url;
bool isLayouts = dispUrl.StartsWith("_layouts/",StringComparison.CurrentCultureIgnoreCase);
dispUrl = String.Format("{0}/{1}?ID={2}",webUrl,dispUrl,item.ID);
if(isLayouts)
dispUrl = String.Format("{0}&List={1}",dispUrl,SPEncode.UrlEncode(list.ID+""));

As a result, you will get full display form URL of a list item. However, if you want to get just a “clickable” URL, to place in some hyperlink, you don’t need to write so much code. You may create URL by using only an address of a list display form. SharePoint will analyze provided ID of an item then and redirect your request to appropriate page. You may code just:

SPListItem item = GetItem(); // some code to get a list item
SPList list = item.ParentList;
SPWeb web = list.ParentWeb;
string webUrl = web.Url;
string dispUrl = list.Forms[PAGETYPE.PAGE_DISPLAYFORM].Url;;
dispUrl = String.Format("{0}/{1}?ID={2}",webUrl,dispUrl,item.ID);