Windows.Storage on WP8 gives me Deserialize exception

Question

I'm trying to save an ObservableCollection using the new method in windows phone (Windows.Storage). I have the following class which is the base for my observable collection I want to save:

    [DataContract]
    class SettingsModel : INotifyPropertyChanged
    {

        public SettingsModel()
        { }

        [DataMember]
        private string _TargetIP {get; set;}

        public string TargetIP
        {
            get 
            {
                return _TargetIP;
            }
            set
            {
                _TargetIP = value;
                NotifyPropertyChanged("TargetIP");
            }
        }

        [DataMember]
        private string _TargetADS { get; set; }

        public string TargetADS
        {
            get
            {
                return _TargetADS;
            }
            set
            {
                _TargetADS = value;
                NotifyPropertyChanged("TargetADS");
            }
        }

        [DataMember]
        private string _ClientIP { get; set; }

        public string ClientIP
        {
            get 
            {
                return _ClientIP;
            }
            set
            {
                _ClientIP = value;
                NotifyPropertyChanged("ClientIP");
            }
        }

        [DataMember]
        private string _ClientADS { get; set; }

        public string ClientADS
        {
            get 
            {
                return _ClientADS;
            }
            set
            {
                _ClientADS = value;
                NotifyPropertyChanged("ClientADS");
            }
        }

        #region Notify property changed
        public event PropertyChangedEventHandler PropertyChanged;

        private void NotifyPropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        #endregion
    }
}

My Code to save the observable collection is this:

    public static async void SaveCollection<T>(string FileName, string FileExtension, ObservableCollection<T> Col) where T : class
    {
        // place file extension
        FileName = FileName + "." + FileExtension;

        // creating the file and replace the current file if the file allready exists
        var file = await Windows.Storage.ApplicationData.Current.LocalFolder.CreateFileAsync
            (FileName, 
            Windows.Storage.CreationCollisionOption.ReplaceExisting);

        // openup a new stream to the file (write)
        using (var Stream = await file.OpenStreamForWriteAsync())
        {

            // serialize the observable collection to a writable type
            var DataSerializer = new DataContractSerializer(typeof(ObservableCollection<T>),
                new Type[] { typeof(T) });

            // write data
            DataSerializer.WriteObject(Stream, Col);
        }
    }

The Call of the Static SaveCollection<t> method:

StorageHandler.SaveCollection<SettingsModel>("TestData", "txt", Data);

in which Data is the collection which is based on the settingsModel. The call gives me an error on the last line of the SaveCollection method. The error of the dataserializer:

An exception of type 'System.Security.SecurityException' occurred in System.Runtime.Serialization.ni.dll but was not handled in user code

Additional information: The collection data contract type 'System.Collections.ObjectModel.ObservableCollection`1[[WP_ADS.Model.SettingsModel, WP_ADS, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]' cannot be deserialized because it does not have a public parameterless constructor. Adding a public parameterless constructor will fix this error. Alternatively, you can make it internal, and use the InternalsVisibleToAttribute attribute on your assembly in order to enable serialization of internal members - see documentation for more details. Be aware that doing so has certain security implications.

Any idea how to fix this?

(as the error suggests, I've already tried adding a parameterless constructor, making the constructor internal but both to no avail).

Answer 1

Don't forget to set your class to public.

Answer 2

Put the [DataMember] at the public property