windows phone 7 IsolatedStorageSettings.ApplicationSettings complex data - windows-phone-7

Question

Just a quick question. In WP7, is it really bad design/idea to store complex data using IsolatedStorageSettings.ApplicationSettings? I want to save a collection of some class objects. The properties are marked with [DataMember] attributes.
An example of a class would be,
[DataContract]
public class OfflineItem
{
[DataMember]
public string Id { get; set; }
[DataMember]
public MyItem Item { get; set; }
[DataMember]
public Dictionary<string, string> KeyValues { get; set; }
}
Collection<OfflineItems> offlineItems = new Collection<OfflineItems>();
.....
IsolatedStorageSettings.ApplicationSettings["AllOfflineItems"] = offlineItems;
I tried it and it worked, but I want to know if it is a correct approach and will there be any performance hit in the long run?

Answer 1

#Jonna. I deliberated over this one too. I ended up using/adapating the following generic methods to serialize and deserialize using a IsolatedStorageFile as below. It includes deleting a file if it already exists as you are trying to update the data.
internal static void Write<T>(T obj, string fileName)
{
XmlWriterSettings writerSettings = new XmlWriterSettings
{
Indent = true,
IndentChars = "\t"
};
try
{
using (var isoStore = IsolatedStorageFile.GetUserStoreForApplication())
{
if (isoStore.FileExists(fileName))
{
isoStore.DeleteFile(fileName);
}
using (var isoStream = new IsolatedStorageFileStream(fileName, FileMode.Create, isoStore))
{
XmlSerializer serializer = new XmlSerializer(typeof(T));
using (XmlWriter xmlWriter = XmlWriter.Create(isoStream, writerSettings))
{
serializer.Serialize(xmlWriter, obj);
}
}
}
}
catch (IsolatedStorageException ex)
{
Debug.WriteLine(ex.Message);
}
catch (Exception emAll)
{
Debug.WriteLine(emAll.Message);
}
}
internal static T Read<T>(string fileName)
{
try
{
using (var isoStore = IsolatedStorageFile.GetUserStoreForApplication())
{
using (var isoStream = new IsolatedStorageFileStream(fileName, FileMode.Open, isoStore))
{
XmlSerializer serializer = new XmlSerializer(typeof(T));
return (T)serializer.Deserialize(isoStream);
}
}
}
catch (IsolatedStorageException ex)
{
Debug.WriteLine(ex.Message);
throw;
}
catch (Exception emAll)
{
Debug.WriteLine(emAll.Message);
throw;
}
}
Serialization would be called thus:
Serialization.Write<user>(userDetails, App.USERDETAILS);
And deserialization would be called thus:
Items = Serialization.Read<measurements>(App.MEASUREMENTS);
user is a class and userDetails is an object based on the that class. Measurements is a class and Items is an object based on that class. App.USERDETAILS & App.MEASUREMENTS are global strings that contain file names.
Some debug lines have been left in just so progress can be tracked.
It might also be worth considering using SQL + LINQ if you are thinking of migrating to Mango and much of this could be taken care of there...

Answer 2

I would serialize my data (either XML or Binary) to a separate file in IsolatedStorage. Because if IsolatedStorageSettings.ApplicationSettings is overcrowded it will take longer to load any of individual settings.
Here is a general purpose method to serialize your object to xml
public static string SerializeXml(object objectToSerialize)
{
using (var ms = new MemoryStream())
{
var serializer = new XmlSerializer(objectToSerialize.GetType());
serializer.Serialize(ms, objectToSerialize);
ms.Position = 0;
using (var reader = new StreamReader(ms))
{
return reader.ReadToEnd();
}
}
}