Deserializing XML with DataContractSerializer

Question

I have a web service that returns the following data:

<?xml version=""1.0"" encoding=""UTF-8""?>
<RESPONSE>
    <KEY>12345</KEY>
    <PROPERTY>
        <PROPERTY_ADDRESS>
            <STREET_NUM>25</STREET_NUM>
            <STREET_ADDRESS>ELM ST</STREET_ADDRESS>
            <STREET_PREFIX/>
            <STREET_NAME>ELM</STREET_NAME>
            <STREET_TYPE>ST</STREET_TYPE>
            <STREET_SUFFIX/>
        </PROPERTY_ADDRESS>
    </PROPERTY>
</RESPONSE>

I have a class structure to match:

[DataContract(Name="RESPONSE", Namespace="")]
public class Response
{
    [DataMember(Name="KEY")]
    public string Key { get; set; }

    [DataMember(Name = "PROPERTY")]
    public Property Property { get; set; }
}

[DataContract(Name="PROPERTY", Namespace="")]
public class Property
{
    [DataMember(Name="PROPERTY_ADDRESS")]
    public PropertyAddress Address { get; set; }
}


[DataContract(Name="PROPERTY_ADDRESS", Namespace="")]
public class PropertyAddress
{
    [DataMember(Name="STREET_NUM")]
    public string StreetNumber { get; set; }

    [DataMember(Name = "STREET_ADDRESS")]
    public string StreetAddress { get; set; }

    [DataMember(Name = "STREET_PREFIX")]
    public string StreetPrefix { get; set; }

    [DataMember(Name = "STREET_NAME")]
    public string StreetName { get; set; }

    [DataMember(Name = "STREET_TYPE")]
    public string StreetType { get; set; }

    [DataMember(Name = "STREET_SUFFIX")]
    public string StreetSuffix { get; set; }
}

My deserialization code looks like this:

[Test]
public void TestMapping()
{
    var serializer = new DataContractSerializer(typeof(Response));

    Response response = null;

    using (var ms = new MemoryStream(Encoding.UTF8.GetBytes(XmlData)))
    {
        response = (Response)serializer.ReadObject(ms);
    }

    //This works
    Assert.AreEqual("12345", response.Key);

    //This works
    Assert.AreEqual("25", response.Property.Address.StreetNumber);

    //This FAILS. StreetAddress is null
    Assert.AreEqual("ELM ST", response.Property.Address.StreetAddress);
}

For the life of me I can't figure out why StreetAddress is failing. It's got to be something simple that I'm missing.

what value are you getting in those property exactly, can you do a testcontext.writeline on each property to see the value. — Son_of_Sam, Mar 14 '13 at 15:35
response.Property.Address.StreetNumber == "25" response.Property.Address.StreetAddress == null — Micah, Mar 14 '13 at 15:36
Change StreetAddress to int to see if it's the property name or type failing. — rick schott, Mar 14 '13 at 15:42
The syntax of your XML is incorrect. The closing tag is missing a /. If this is exactly what your service is returning, that's got to be throwing off deserialization. — SWalters, Mar 14 '13 at 15:43
@SandraWalters: That was a typeo in my question but not in the actual data — Micah, Mar 14 '13 at 15:48
If you remove that property, does the next string property fail? — rick schott, Mar 14 '13 at 15:48
@rickschott yeah it fails too, but STREET_TYPE works just fine. — Micah, Mar 14 '13 at 15:52
I getting the same results. The street address have a null value — Son_of_Sam, Mar 14 '13 at 15:53
What's even more strange is that if you change the order of the xml (like move STREET_ADDRESS to the top) it magically deserializes that property correctly. — Micah, Mar 14 '13 at 16:06
Possible duplicate of [WCF DataContract DataMember order?](http://stackoverflow.com/questions/3816478/wcf-datacontract-datamember-order) — chwarr, Apr 23 '16 at 02:32

score 26 · Accepted Answer · edited May 23 '17 at 12:01

26

DataContractSerializer expects things to be in alphabetical order. You need to add Order to your Data Members for this to work correctly.

[DataContract(Name = "PROPERTY_ADDRESS", Namespace = "")]
public class PropertyAddress
{
    [DataMember(Name = "STREET_NUM", Order=0)]
    public string StreetNumber { get; set; }

    [DataMember(Name = "STREET_ADDRESS", Order=1)]
    public string StreetAddress { get; set; }

    [DataMember(Name = "STREET_PREFIX", Order=2)]
    public string StreetPrefix { get; set; }

    [DataMember(Name = "STREET_NAME", Order=3)]
    public string StreetName { get; set; }

    [DataMember(Name = "STREET_TYPE", Order=4)]
    public string StreetType { get; set; }

    [DataMember(Name = "STREET_SUFFIX",Order=5)]
    public string StreetSuffix { get; set; }
}

edited May 23 '17 at 12:01

Community

1
1

answered Mar 14 '13 at 16:09

vcsjones

138,677
31
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@Micah: Its for performance reason. By expecting the tags in a certain order DataContractSerializer can save time on matching the contract's tags with the message tags. And there has to be some default order if none is specified explicitly. – Vizu Mar 14 '13 at 16:47
22

I think that any 'performance' gains are more than offset by the sheer amount of wasted developer time in trying to find, debug, and fix this silly requirement. – Carl Onager Jul 01 '13 at 08:29
So... how do you disable this behavior? – BrainSlugs83 Sep 27 '13 at 22:30
@BrainSlugs83 Not easily. The best thing at this point is to just set the `Order` property on the attribute. You can use `IDispatchMessageInspector.AfterReceiveRequest` to re-format the incoming request, or use a different serialization library. – vcsjones Sep 29 '13 at 13:35
2

This is really frustrating, I just spent 3 hours figuring out that was the problem. – SecureTeam Software Oct 01 '13 at 17:59
2

@EranD. I also just spent about 3 hours before I finally came to find this out...FML. And Microsoft wonders why developers become disillusioned with their products. – crush Mar 10 '14 at 18:59
10

I want to give an upvote for the accuracy and usefulness of your answer, but a downvote for the awful truth it contains. ;) – teedyay Jul 09 '14 at 09:28
I spent hours to figure this hour. I was why the hell the compiler is behaving so discriminatory that reads all the other xml elements, except this newly added one. Thanks. [tears of joy on my face right now] – Ben Aug 01 '14 at 14:39

score 7 · Answer 2 · answered Mar 14 '13 at 16:09

You have to augment your data contract with the order of the elements because DataContractSerializer expects the elements to be sorted alphabetically by default. Which is not the case with your XML.

Here's the code:

[DataContract(Name = "PROPERTY_ADDRESS", Namespace = "")]
public class PropertyAddress
{
    [DataMember(Name = "STREET_NUM", Order=1)]
    public string StreetNumber { get; set; }

    [DataMember(Name = "STREET_ADDRESS", Order=2)]
    public string StreetAddress { get; set; }

    [DataMember(Name = "STREET_PREFIX", Order=3)]
    public string StreetPrefix { get; set; }

    [DataMember(Name = "STREET_NAME", Order=4)]
    public string StreetName { get; set; }

    [DataMember(Name = "STREET_TYPE", Order=5)]
    public string StreetType { get; set; }

    [DataMember(Name = "STREET_SUFFIX", Order=6)]
    public string StreetSuffix { get; set; }
}

Deserializing XML with DataContractSerializer

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