Custom SettingsProvider and retrieving default value

Question

I have implemented my own class that inherits from the SettingsProvider class. If the value I am retrieving has not been set by the user, i.e. it is the first time the program starts, I attempt to grab the default value. The problem I am seeing is when the default value is retrieved from the SettingsProperty it comes back as a string. I have tried to add some code that converts the item but I am running into problems when converting System.Drawing.Colors and am receiving the error "Invalid cast from 'System.String' to 'System.Drawing.Color'.".

Here is an example of the code I am using to get the default value:

 private object GetDefaultValue(SettingsProperty setting)
  {
         if (setting.PropertyType.IsEnum)
             return Enum.Parse(setting.PropertyType, setting.DefaultValue.ToString());

        // Return the default value if it is set
        if (setting.DefaultValue != null)
           return Convert.ChangeType(setting.DefaultValue, setting.PropertyType);
        else // If there is no default value return the default object
           return Activator.CreateInstance(setting.PropertyType);
   }

How can I properly convert the default value to the correct type?

score 1 · Accepted Answer · answered Feb 16 '11 at 23:42

Ok. So I found the answer. Instead of using Convert.ChangeType you need to actually create a TypeConverter instance against the settings.PropertyType. This code Works:

private object GetDefaultValue(SettingsProperty setting)
  {
         if (setting.PropertyType.IsEnum)
             return Enum.Parse(setting.PropertyType, setting.DefaultValue.ToString());

        // Return the default value if it is set
        // Return the default value if it is set
         if (setting.DefaultValue != null)
         {
             System.ComponentModel.TypeConverter tc = System.ComponentModel.TypeDescriptor.GetConverter(setting.PropertyType);
             return tc.ConvertFromString(setting.DefaultValue.ToString());
         }
         else // If there is no default value return the default object
         {
             return Activator.CreateInstance(setting.PropertyType);
         }
   }

Custom SettingsProvider and retrieving default value

1 Answers1