Xml deserialization not binding list

Question

I have a XML file looking like this:

<Stamdata xmlns="http://schemas.datacontract.org/2004/07/a">
  <Liste xmlns:d3p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic">
    <d3p1:KeyValuePairOfStringDatagxNgnmsk>
      <d3p1:key>key value</d3p1:key>
      <d3p1:value>
        ......
      </d3p1:value>
    </d3p1:KeyValuePairOfStringDatagxNgnmsk>
  </Liste>
</Stamdata>

Any my models looks like

[DataContract(Name = "Stamdata", Namespace = "http://schemas.datacontract.org/2004/07/a")]
public class Stamdata
{
   [DataMember]
   public KeyValuePair<string, Data>[] Liste { get; set; }
}

[DataContract(Name = "Data", Namespace = "http://schemas.datacontract.org/2004/07/System.Collections.Generic")]
public class Data
{
   //.... Many properties
}

My problem is that the list keeps containing 0 elements, even thought the xml contains around 100.

And I'm not sure id the "gxNgnmsk" at the end of <d3p1:KeyValuePairOfStringDatagxNgnmsk> means anything... the one behind the response doesn't know wither what it is.

See : https://stackoverflow.com/questions/2911514/why-doesnt-xmlserializer-support-dictionary It is very easy to do using XML Linq. — jdweng, Sep 03 '18 at 10:59
@Icepickle The one that was lowercase was a typo on my part here at the site — Joshlo, Sep 03 '18 at 11:10
Can you [edit] your question to share sample XML that includes some of the values of `Data`? That would indicate the namespace of the elements of `Data` itself. `"http://schemas.datacontract.org/2004/07/System.Collections.Generic"` is almost certainly the wrong namespace for `Data` but there's not enough information to determine what the correct namespace should be. — dbc, Sep 03 '18 at 18:29

score 0 · Answer 1 · answered Sep 03 '18 at 19:18

The "gxNgnmsk" at the end of <d3p1:KeyValuePairOfStringDatagxNgnmsk> is the cause of your problem. The presence of this suffix is explained in Data Contract Names for Generic Types:

Special rules exist for determining data contract names for generic types...

By default, the data contract name for a generic type is the name of the type, followed by the string "Of", followed by the data contract names of the generic parameters, followed by a hash computed using the data contract namespaces of the generic parameters. ... When all of the generic parameters are primitive types, the hash is omitted.

The "gxNgnmsk" is the hash. And if I use your classes to generate XML from instances created in memory, I get a different hash:

<Stamdata xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/a">
  <Liste xmlns:d2p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic">
    <d2p1:KeyValuePairOfstringDatatwCi8m_S7>
      <d2p1:key>key value</d2p1:key>
      <d2p1:value />
    </d2p1:KeyValuePairOfstringDatatwCi8m_S7>
  </Liste>
</Stamdata>

Apparently your Data type does not have the correct data contract namespace, causing an inconsistent hash to get generated. (And, from experiment, neither "http://schemas.datacontract.org/2004/07/System.Collections.Generic" nor "http://schemas.datacontract.org/2004/07/a" nor "" seem to generate the correct hash. Possibly I could guess the correct namespace from a complete XML sample, but there's not enough information in the simplified XML provided.)

So, what can be done to fix this?

You could get the "one behind the response" to tell you the correct data contract name and namespace for all contract types including Data. This is necessary anyway for data contract equivalence when sending data over the wire so they should be able to provide this information.
If the "one behind the response" provides a WSDL (and they should) you should be able to auto-generate a client which should just work.

But in the absence of the above, you can work around the problem by creating a collection with a custom collection data contract with the hash baked in:

[DataContract(Name = "Stamdata", Namespace = "http://schemas.datacontract.org/2004/07/a")]
public class Stamdata
{
    [DataMember]
    public DataList Liste { get; set; }
}

[CollectionDataContract(
    Namespace = "http://schemas.datacontract.org/2004/07/System.Collections.Generic",
    ItemName = "KeyValuePairOfStringDatagxNgnmsk")]
public class DataList : List<KeyValuePair<string, Data>>
{
    public DataList() : base() { }

    public DataList(IEnumerable<KeyValuePair<string, Data>> list) : base(list) { }
}

With this version of Stamdata the sample XML can be deserialized without knowing the correct namespace for Data.

Xml deserialization not binding list

1 Answers1