get { return this.IsTrackingViewState; }
}
+ // MSDN: The ToString method returns the Name property of the Parameter object. If the Parameter object has no name, ToString returns String.Empty.
public override string ToString ()
{
- object o = GetValue (HttpContext.Current, null);
- if (o != null) return o.ToString();
- return "";
+ return Name;
}
[WebCategoryAttribute ("Parameter")]
get { return isTrackingViewState; }
}
+ // MSDN: The default implementation of the Evaluate method is to return
+ // a null reference (Nothing in Visual Basic) in all cases.
+ // Classes that derive from the Parameter class override the Evaluate method
+ // to return an updated parameter value. For example, the ControlParameter object
+ // returns the value of the control that it is bound to, while
+ // the QueryStringParameter object retrieves the current name/value pair from
+ // the HttpRequest object.
protected virtual object Evaluate (HttpContext context, Control control)
{
- return this.DefaultValue;
+ return null;
}
-
- internal object GetValue (HttpContext context, Control control)
+
+ internal void UpdateValue (HttpContext context, Control control)
{
object oldValue = ViewState ["ParameterValue"];
-
- object newValue = ConvertValue (Evaluate (context, control));
- if (newValue == null)
- newValue = ConvertValue (DefaultValue);
+
+ object newValue = Evaluate (context, control);
if (!object.Equals (oldValue, newValue)) {
ViewState ["ParameterValue"] = newValue;
OnParameterChanged ();
}
- return newValue;
+ }
+
+ internal object GetValue (HttpContext context, Control control)
+ {
+ UpdateValue (context, control);
+
+ object value = ConvertValue (ViewState ["ParameterValue"]);
+ if (value == null)
+ value = ConvertValue (DefaultValue);
+
+ return value;
}
- object ConvertValue (object val)
+ internal object ConvertValue (object val)
{
if (val == null) return null;
if (ConvertEmptyStringToNull && val.Equals (string.Empty))
return null;
- return Convert.ChangeType (val, Type);
+ return Type != TypeCode.Empty ? Convert.ChangeType (val, Type) : val;
}
protected internal virtual void SetDirty()