Custom Type within ArrayList inside of the user profile in C#

I'm getting the following error when trying to save a custom class within my ArrayList within my user profile:

There was an error generating the XML document. ---> System.InvalidOperationException: The type Com.xxx.MyDataClass was not expected. Use the XmlInclude or SoapInclude attribute to specify types that are not known statically.

My web.config has something like:

<profile enabled="true" automaticSaveEnabled="false" defaultProvider="xxxxxxProvider">
  <properties>
    <add name="MyData" type="System.Collections.ArrayList"/>
  </properties>
</profile>

I am trying to store my class called (something like) MyDataClass in an ArrayList into MyData. When I save I get the error above. The class MyDataClass has just two members for now, both set as 'string'.

I assume I have to tell the class has to serialize itself but I'm not sure how.

Here's the class:

namespace Com.xxxx.DataClasses
{
    public class MyDataClass : ISerializable
    {
        public string elem1;
        public string elem2;

        public string Elem1
        {
            get { return elem1; }
            set { elem1 = value; }
        }

        public string Elem2
        {
            get { return elem2; }
            set { elem2 = value; }
        }
....

UPDATE: FIXED

I was able to fix this issue via the following:

First of all here is a good resource: http://msdn.microsoft.com/en-us/library/d8b58y5d.aspx

I changed the profile entries to be:

<profile enabled="true" automaticSaveEnabled="false" defaultProvider="xxxxxxProvider">
  <properties>
    <add name="MyDat开发者_如何学Ca" type="mypackage.MyDataClass" serializeAs="binary"/>
  </properties>
</profile>

and then I created MyDataClass to contain a List<> of MyDataClassInfo objects similar to:

namespace Com.xxxx.DataClasses
{
    [Serializable]
    public class MyDataClass
    {
        List<MyDataClassInfo> myDataClassInfo;

        public MyDataClassInfo()
        {
            myDataClassInfo = new List<MyDataClassInfo>;
        }
        public List<MyDataClassInfo> MyDataClassInfo
        {
             get;
             set;
        }
    }


    [Serializable]
    public class MyDataClassInfo
    {
        public string elem1;
        public string elem2;

        public string Elem1
        {
            get { return elem1; }
            set { elem1 = value; }
        }

        public string Elem2
        {
            get { return elem2; }
            set { elem2 = value; }
        }
....

The key here was 1) using the serializeAt="binary" and 2) using a class which contained a list instead of a list within the profile.

You should never use the ArrayList class. It is deprecated as of .NET 2.0.

Use List<MyDataClass> instead. It may even solve this problem for you.

Try decorating MyDataClass with SerializableAttribute.

namespace Com.xxxx.DataClasses
{
    [Serializable]
    public class MyDataClass
    {
        public string elem1;
        public string elem2;

        public string Elem1
        {
            get { return elem1; }
            set { elem1 = value; }
        }

        public string Elem2
        {
            get { return elem2; }
            set { elem2 = value; }
        }
    ....