Creating a generic method in C#

Question

I am trying to combine a bunch of similar methods into a generic method. I have several methods that return the value of a querystring, or null if that querystring does not exist or is not in the correct format. This would be easy enough if all the types were natively nullable, but I have to use the nullable generic type for integers and dates. Here's what I have now. However, it will pass back a 0 if a numeric value is invalid, and that unfortunately is a valid value in my scenarios. Can somebody help me out? Thanks! ``` public static T GetQueryString<T>(string key) where T : IConvertible { T result = default(T); if (String.IsNullOrEmpty(HttpContext.Current.Request.QueryString[key]) == false) { string value = HttpContext.Current.Request.QueryString[key]; try { result = (T)Convert.ChangeType(value, typeof(T)); } catch { //Could not convert. Pass back default value... result = default(T); } } return result; } ```

Accepted Answer

What if you specified the default value to return, instead of using default(T)?

```
public static T GetQueryString<T>(string key, T defaultValue) {...}
```

It makes calling it easier too:

```
var intValue = GetQueryString("intParm", Int32.MinValue);
var strValue = GetQueryString("strParm", "");
var dtmValue = GetQueryString("dtmPatm", DateTime.Now); // eg use today's date if not specified
```

The downside being you need magic values to denote invalid/missing querystring values.

Creating a generic method in C#

Solution

Problem