How do you test your Request.QueryString[] variables?

Question

I frequently make use of Request.QueryString[] variables.

In my Page_load I often do things like:

       int id = -1;

             


        

Answer 1

I'm using a little helper method:

public static int QueryString(string paramName, int defaultValue)
{
    int value;
    if (!int.TryParse(Request.QueryString[paramName], out value))
        return defaultValue;
    return value;
}

This method allows me to read values from the query string in the following way:

int id = QueryString("id", 0);

Answer 2

Eeee this is a karma risk...

I have a DRY unit-testable abstraction because, well, because there were too many querystring variables to keep on in a legacy conversion.

The code below is from a utility class whose constructor requires a NameValueCollection input (this.source) and the string array "keys" is because the legacy app was rather organic and had developed the possibility for several different strings to be a potential input key. However I kind of like the extensibility. This method inspects the collection for the key and returns it in the datatype required.

private T GetValue<T>(string[] keys)
{
    return GetValue<T>(keys, default(T));
}

private T GetValue<T>(string[] keys, T vDefault)
{
    T x = vDefault;

    string v = null;

    for (int i = 0; i < keys.Length && String.IsNullOrEmpty(v); i++)
    {
        v = this.source[keys[i]];
    }

    if (!String.IsNullOrEmpty(v))
    {
        try
        {
            x = (typeof(T).IsSubclassOf(typeof(Enum))) ? (T)Enum.Parse(typeof(T), v) : (T)Convert.ChangeType(v, typeof(T));
        }
        catch(Exception e)
        {
            //do whatever you want here
        }
    }

    return x;
}

Answer 3

Use int.TryParse instead to get rid of the try-catch block:

if (!int.TryParse(Request.QueryString["id"], out id))
{
  // error case
}

Answer 4

You can use the extension methods below as well and do like this

int? id = Request["id"].ToInt();
if(id.HasValue)
{

}

// Extension methods

public static int? ToInt(this string input) 
{
    int val;
    if (int.TryParse(input, out val))
        return val;
    return null;
}

public static DateTime? ToDate(this string input)
{
    DateTime val;
    if (DateTime.TryParse(input, out val))
        return val;
    return null;
}

public static decimal? ToDecimal(this string input)
{
    decimal val;
    if (decimal.TryParse(input, out val))
        return val;
    return null;
}

Answer 5

Try this dude...

List<string> keys = new List<string>(Request.QueryString.AllKeys);

Then you will be able to search the guy for a string real easy via...

keys.Contains("someKey")

Answer 6

Well for one thing use int.TryParse instead...

int id;
if (!int.TryParse(Request.QueryString["id"], out id))
{
    id = -1;
}

That assumes that "not present" should have the same result as "not an integer" of course.

EDIT: In other cases, when you're going to use request parameters as strings anyway, I think it's definitely a good idea to validate that they're present.