Check if SharePoint site collection exists

Question

I'm am troubled that this simple tasks has proven so difficult. I've tried several different techniques to check if a URL exists but none are acceptable. Using HttpWebRequest, it returns 403 on SharePoint site since the request is not authenticated.

Using the PnP library, it returns true even when a site exists. It seems to only look at the domain and not site collections or webs.

public static bool DoesSPOSiteExist(string url, NetworkCredential nc)
        {
            OfficeDevPnP.Core.AuthenticationManager authMgr = new OfficeDevPnP.Core.AuthenticationManager();

           try
           {
                // Get the client context  
                using (var ctx = authMgr.GetSharePointOnlineAuthenticatedContextTenant(url, nc.UserName, nc.Password))
                {
                    // Check if a web site exists at the specified full URL  
                    if (ctx.WebExistsFullUrl(url))
                    {
                        //gets here even when you pass in a bad URL
                        Console.WriteLine(url + " - site exists");
                    }
                    return true;
                }
            }

            catch (Exception ex)
            {
                return false;
            }
        }

Is there an alternative to see if a site exists using C# CSOM ?

Answer 1

You're using the same variable url that you used to instantiate the context. So of course the web is going to exist.

If you set the url variable to a junk value, you won't get a valid context. It'll either be null, or it'll throw an exception, depending on the implementation of GetSharePointOnlineAuthenticatedContextTenant()