How to Use XmlSerializer to Serialize Collections of Objects

Question

Here are the steps I've taken so far to work with an XmlDocument being returned by a 3rd party DLL.

1. I saved the XmlDocument as SegmentationSummary.xml.
2. I used XSD.exe to create SegmentationSummary.xsd.
3. I used XSD.exe to create SegmentationSummary.cs.

Here is a sample of SegmentationSummary.cs. Note that ShmResult is the root node representation.

/// <remarks/>
[System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.3038")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true, Namespace = "omitted")]
[System.Xml.Serialization.XmlRootAttribute(Namespace = "omitted", IsNullable = false)]
public partial class ShmResult
{
    private ShmResultDownloadDetail[] downloadDetailField;

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute("DownloadDetail")]
    public ShmResultDownloadDetail[] DownloadDetail
    {
        get
        {
            return this.downloadDetailField;
        }
        set
        {
            this.downloadDetailField = value;
        }
    }
}

/// <remarks/>
[System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.3038")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true, Namespace = "omitted")]
public partial class ShmResultDownloadDetail
{
    private string modelCodeField;

    /// <remarks/>
    public string ModelCode
    {
        get
        {
            return this.modelCodeField;
        }
        set
        {
            this.modelCodeField = value;
        }
    }
}

Now, I wanted to use this to read the XmlDocument and begin working with the classes in SegmentationSummary.cs. Here's the code I wrote:

private XmlDocument _document;
SegmentationSummary.ShmResult _Result;
    private void LoadXML()
    {
        XmlReader xmlRdr = new XmlNodeReader(_document);
        System.Xml.Serialization.XmlSerializer s = new System.Xml.Serialization.XmlSerializer(typeof(SegmentationSummary.ShmResult));
        _Result = (SegmentationSummary.ShmResult)s.Deserialize(xmlRdr);
    }

When LoadXML() is executed, I get exceptions of this variety:

Test method SegmentationSummaryHandlerTest.TestMethod1 threw exception: System.InvalidOperationException: Unable to generate a temporary class (result=1). error CS0030: Cannot convert type 'MERC.AIRCAT.SHMCoreInterface.SegmentationSummary.ShmResultDownloadDetail[]' to 'MERC.AIRCAT.SHMCoreInterface.SegmentationSummary.ShmResultDownloadDetail' error CS0029: Cannot implicitly convert type 'MERC.AIRCAT.SHMCoreInterface.SegmentationSummary.ShmResultDownloadDetail' to 'MERC.AIRCAT.SHMCoreInterface.SegmentationSummary.ShmResultDownloadDetail[]'

Now, the FAQ at http://msdn.microsoft.com/en-us/library/ms950721.aspx states the following:

Q: How do I serialize collections of objects?

A: The XmlSerializer throws an exception when the collection contains types that were not declared to the constructor of the XmlSerializer. You can:

1. Declare the types to the serializer by passing in a Type[] with the types to expect within the collection.

   OR

2. Implement a strongly-typed collection derived from System.Collections.CollectionBase with an indexer matching the Add() method.

My question is: Which of these is "best" and how do I go about implementing the solution?

Answer 1

I've always used option 2 there, so for you, something a little like this might work:

public class ShmResult : List<ShmResultDownloadDetail> { }