ASP.Net How to enforce the HTTP get URL format?

Question

[Sorry about a messy question. I believe I am targeting .Net 2.0 (for now)]

Hi, I am an ASP.NET noob. For starters I am building a page that parses a URL string and populates a table in a database. I want that string to be strictly of the form:

http://<server>:<port>/PageName.aspx?A=1&B=2&C=3&D=4&E=5

The order of the arguments does not matter, I just do not want any of them missing, or any extras. Here is what I tried (yes, it is ugly; I just want to get it to work first):

#if (DEBUG)
        // Maps parameter names to their human readable names.
        // Used for error checking.
        private static Dictionary<string, string> paramNameToDisplayName = new Dictionary<string, string> {
            { "A", "a"},
            { "B", "b"},
            { "C", "c"},
            { "D", "d"},
            { "E", "e"},
            { "F", "f"},
       };


        [Conditional("DEBUG")]
        private void validateRequestParameters(HttpRequest request)
        {
            bool endResponse = false;
            // Use foreach var
            foreach (string expectedParameterName in paramNameToDisplayName.Keys)
            {
                if (request[expectedParameterName] == null)
                {
                    Response.Write(String.Format("No parameter \"{0}\", aka {1} was passed to the configuration generator. Check your URL string / cookie.",
                        expectedParameterName, paramNameToDisplayName[expectedParameterName]));
                    endResponse = true;
                }
            }
            // Use foreach var
            foreach (string actualParameterName in request.Params)
            {
                if (!paramNameToDisplayName.ContainsKey(actualParameterName))
                {
                    Response.Write(String.Format("The parameter \"{0}\", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.",
                        actualParameterName));
                    endResponse = true;
                }
            }
            if (endResponse)
            {
                Response.End();
            }
        }
#endif

and it works ok, except that it complains about all sorts of other stuff:

http://localhost:1796/AddStatusUpdate.aspx?X=0

---

No parameter "A", aka a was passed to the configuration generator. Check your URL string / cookie.No parameter "B", aka b was passed to the configuration generator. Check your URL string / cookie.No parameter "C", aka c was passed to the configuration generator. Check your URL string / cookie.No parameter "D", aka d was passed to the configuration generator. Check your URL string / cookie.No parameter "E", aka e was passed to the configuration generator. Check your URL string / cookie.No parameter "F", aka f was passed to the configuration generator. Check your URL string / cookie.The parameter "X", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "ASP.NET_SessionId", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "ALL_HTTP", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "ALL_RAW", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "APPL_MD_PATH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "APPL_PHYSICAL_PATH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "AUTH_TYPE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "AUTH_USER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "AUTH_PASSWORD", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "LOGON_USER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_USER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_COOKIE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_FLAGS", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_ISSUER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_KEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SECRETKEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SERIALNUMBER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SERVER_ISSUER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SERVER_SUBJECT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SUBJECT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CONTENT_LENGTH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CONTENT_TYPE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "GATEWAY_INTERFACE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_KEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_SECRETKEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_SERVER_ISSUER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_SERVER_SUBJECT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "INSTANCE_ID", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "INSTANCE_META_PATH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "LOCAL_ADDR", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "PATH_INFO", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "PATH_TRANSLATED", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "QUERY_STRING", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_ADDR", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_HOST", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_PORT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REQUEST_METHOD", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SCRIPT_NAME", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_NAME", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_PORT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_PORT_SECURE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_PROTOCOL", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_SOFTWARE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "URL", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_CACHE_CONTROL", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_CONNECTION", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT_CHARSET", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT_ENCODING", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT_LANGUAGE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_COOKIE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_HOST", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_USER_AGENT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.Thread was being aborted.

---

Is there some way for me to separate the implicit and the explicit parameters, or is it not doable? Should I even bother? Perhaps the philosophy of get is to just throw away that what is not needed.

Thanks!

Answer 1

Your Dictionary should have a string key, your code doesn't have "" around the keys:

private static Dictionary<string, string> paramNameToDisplayName = new Dictionary<string, string> {
    { "A", "a"},
    { "B", "b"},
    { "C", "c"},
    { "D", "d"},
    { "E", "e"},
    { "F", "f"},

};

For the rest of the errors, try using this, your code was looking for all posted params, not just the querystring params (request.QueryString.AllKeys):

if (!request.QueryString.AllKeys.Contains<string>(expectedParameterName))
                {
                    Response.Write(String.Format("No parameter \"{0}\", aka {1} was passed to the configuration generator. Check your URL string / cookie.", expectedParameterName, paramNameToDisplayName[expectedParameterName]));
                    endResponse = true;
                }

Answer 2

As drousseau mentions, you'll need to use the QueryString collection instead of Params. Params includes ALL data passed on the request, which means cookies, form POST data, querystring parameters and servervariables.

It looks like you're checking the cookies as well, so you'll either need to do a separate check through that collection, or merge the two by using something like this:

        var both = (
            from key in Request.QueryString.AllKeys
            select new { Key = key, Value = Request.QueryString[key] }).Union(
            from key in Request.Cookies.AllKeys
            select new { Key = key, Value = Request.Cookies[key].Value }).ToDictionary(entry => entry.Key, entry => entry.Value);

It's also worth noting that you're also going to be getting a cookie dropped by ASP.NET session state. You can either code around it by explicitly ignoring cookies named "ASP.NET_SessionId" (easiest), or just turn off session state in web.config - you'll need to clear your cookies though.

EDIT: just saw the bit about targeting 2.0, which means that nice little LINQ statement is out of the question. It would probably be easiest to just check each of the collections (QueryString and Cookies) separately.

EDIT PART DEUX: Here's a non-LINQ alternative to using a single lookup:

        NameValueCollection both = new NameValueCollection(Request.QueryString);
        foreach (String key in Request.Cookies.AllKeys)
        {
            if (key != "ASP.NET_SessionId") both.Add(key, Request.Cookies[key].Value);
        }

Using a hard-coded string like that is ugly, but hey, it should work.

I'd also like to point out that if you used ASP.NET MVC or even just System.Web.Routing (both of which unfortunately require .NET 3.5), you wouldn't have to do ANY of this, since the routing framework does it all for you - and you'd get typed parameters to boot!