Deserialization and casting problems

[Greg Allen]

I am consuming a web service and using the generated Reference.cs to access
the service and the objects associated with it.

I have run into a problem where some inherited classes are not being
deserialized. I have verified that the XML being returned by the service
contains the tags I am expecting, but they don't show up in the resulting
object. Here's the relevant portion of the Reference.cs file:

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class FormSection {
[System.Xml.Seri alization.XmlEl ementAttribute( "field")]
public FormField[] field;
}
[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
[System.Xml.Seri alization.XmlIn cludeAttribute( typeof(SelectOn eField))]
[System.Xml.Seri alization.XmlIn cludeAttribute( typeof(SelectMu ltipleField))]
[System.Xml.Seri alization.XmlIn cludeAttribute( typeof(BooleanF ield))]
public class FormField {
[System.Xml.Seri alization.XmlEl ementAttribute( "value")]
public string[] value;
[System.Xml.Seri alization.XmlAt tributeAttribut e()]
public FormFieldType type;
}
[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public enum FormFieldType {
boolean,
select1,
selectn,
}
[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
[System.Xml.Seri alization.XmlIn cludeAttribute( typeof(SelectMu ltipleField))]
public class SelectOneField : FormField {
[System.Xml.Seri alization.XmlAr rayItemAttribut e("choice")]
public Choice[] choices;
}
[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class Choice {
public string value;
[System.Xml.Seri alization.XmlAr rayItemAttribut e("field")]
public FormField[] fields;
}
[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class SelectMultipleF ield : SelectOneField {
[System.Xml.Seri alization.XmlAt tributeAttribut e()]
public int maximum_choices ;
[System.Xml.Seri alization.XmlAt tributeAttribut e()]
public int minimum_choices ;
}
[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class BooleanField : FormField {
[System.Xml.Seri alization.XmlAr rayItemAttribut e("field")]
public FormField[] fields;
}

The problem occurs when I get XML like this:

<field type="select1">
<value/>
<choices>
<choice>
<value>17</value>
<fields>
</fields>
</choice>
<choice>
<value>18</value>
<fields>
</fields>
</choice>
</choices>

When this is deserialized, there are no choices! And in code, if I try to
cast
to one of the inherited types, I get an error. Here's the snippet of code:

FormField field = <stuff>.field[0];
switch (field.type)
{
case FormFieldType.b oolean:
string[] boolean_value = {"on"};
field.value = boolean_value;
break;
case FormFieldType.s elect1:
SelectOneField sel1 = (SelectOneField ) field;
string[] select1_value = {sel1.choices[0].value};
field.value = select1_value;
}

The cast to SelectOneField fails with "Specified cast is not valid." Why???

Am I doing something wrong? Is there a bug in the service somewhere?

Any help appreciated.

Thanks,

-- Greg

[Rémy]

"Greg Allen" <ga****@arrayin c.com> a écrit dans le message de news:
%2************* ***@TK2MSFTNGP1 2.phx.gbl...

I am consuming a web service and using the generated Reference.cs to access
the service and the objects associated with it.

I have run into a problem where some inherited classes are not being
deserialized. I have verified that the XML being returned by the service
contains the tags I am expecting, but they don't show up in the resulting
object. Here's the relevant portion of the Reference.cs file:
[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class FormSection {
[System.Xml.Seri alization.XmlEl ementAttribute( "field")]
public FormField[] field;
}

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
[System.Xml.Seri alization.XmlIn cludeAttribute( typeof(SelectOn eField))]

[System.Xml.Seri alization.XmlIn cludeAttribute( typeof(SelectMu ltipleField))]
[System.Xml.Seri alization.XmlIn cludeAttribute( typeof(BooleanF ield))]
public class FormField {
[System.Xml.Seri alization.XmlEl ementAttribute( "value")]
public string[] value;
[System.Xml.Seri alization.XmlAt tributeAttribut e()]
public FormFieldType type;
}

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public enum FormFieldType {
boolean,
select1,
selectn,
}

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]

[System.Xml.Seri alization.XmlIn cludeAttribute( typeof(SelectMu ltipleField))]
public class SelectOneField : FormField {
[System.Xml.Seri alization.XmlAr rayItemAttribut e("choice")]
public Choice[] choices;
}

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class Choice {
public string value;
[System.Xml.Seri alization.XmlAr rayItemAttribut e("field")]
public FormField[] fields;
}

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class SelectMultipleF ield : SelectOneField {
[System.Xml.Seri alization.XmlAt tributeAttribut e()]
public int maximum_choices ;
[System.Xml.Seri alization.XmlAt tributeAttribut e()]
public int minimum_choices ;
}

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class BooleanField : FormField {
[System.Xml.Seri alization.XmlAr rayItemAttribut e("field")]
public FormField[] fields;
}

The problem occurs when I get XML like this:

<field type="select1">
<value/>
<choices>
<choice>
<value>17</value>
<fields>
</fields>
</choice>
<choice>
<value>18</value>
<fields>
</fields>
</choice>
</choices>

When this is deserialized, there are no choices! And in code, if I try to
cast
to one of the inherited types, I get an error. Here's the snippet of
code:

FormField field = <stuff>.field[0];
switch (field.type)
{
case FormFieldType.b oolean:
string[] boolean_value = {"on"};
field.value = boolean_value;
break;
case FormFieldType.s elect1:
SelectOneField sel1 = (SelectOneField ) field;
string[] select1_value = {sel1.choices[0].value};
field.value = select1_value;
}

The cast to SelectOneField fails with "Specified cast is not valid."
Why???

Am I doing something wrong? Is there a bug in the service somewhere?

Any help appreciated.

Thanks,

-- Greg

I guess your WSDL define "choices" as a sequence of "choice".

I have the same problem.

It seems to be a bug in the code generator when he find a sequence
containing only one type: the generated code define an array of "choice",
but nothing to handle the "choices" level.

At run time an exception is raised during de-serialization stating a
"choices" was found where a "choice" was expected, and no deserialization
occurs.
You may try to use a list instead of a sequence (i have not tried that).

I found an ugly workaround: add a second field named "dummy" in the
definition of choices and make this field optional (minOccurs="0") .

The generated code is completly different (no more arrays), but now correct.

Rémy

[Greg Allen]

OK, here's the relevant section from the WSDL file:

<s:complexTyp e name="FormSecti on">
<s:sequence>
<s:element minOccurs="0" maxOccurs="unbo unded" name="field"
type="tns:FormF ield" />
</s:sequence>
</s:complexType>
<s:complexTyp e name="FormField ">
<s:sequence>
<s:element minOccurs="0" maxOccurs="unbo unded" name="value"
type="s:string" />
</s:sequence>
<s:attribute name="type" type="tns:FormF ieldType" use="required" />
</s:complexType>
<s:simpleType name="FormField Type">
<s:restrictio n base="s:string" >
<s:enumeratio n value="boolean" />
<s:enumeratio n value="select1" />
<s:enumeratio n value="selectn" />
</s:restriction>
</s:simpleType>
<s:complexTyp e name="BooleanFi eld">
<s:complexConte nt mixed="false">
<s:extension base="tns:FormF ield">
<s:sequence>
<s:element minOccurs="0" maxOccurs="1" name="fields"
type="tns:Array OfFormField" />
</s:sequence>
</s:extension>
</s:complexConten t>
</s:complexType>
<s:complexTyp e name="ArrayOfFo rmField">
<s:sequence>
<s:element minOccurs="0" maxOccurs="unbo unded" name="field"
nillable="true" type="tns:FormF ield" />
</s:sequence>
</s:complexType>
<s:complexTyp e name="SelectOne Field">
<s:complexConte nt mixed="false">
<s:extension base="tns:FormF ield">
<s:sequence>
<s:element minOccurs="0" maxOccurs="1" name="choices"
type="tns:Array OfChoice" />
</s:sequence>
</s:extension>
</s:complexConten t>
</s:complexType>
<s:complexTyp e name="ArrayOfCh oice">
<s:sequence>
<s:element minOccurs="0" maxOccurs="unbo unded" name="choice"
nillable="true" type="tns:Choic e" />
</s:sequence>
</s:complexType>
<s:complexTyp e name="Choice">
<s:sequence>
<s:element minOccurs="0" maxOccurs="1" name="value"
type="s:string" />
<s:element minOccurs="0" maxOccurs="1" name="fields"
type="tns:Array OfFormField" />
</s:sequence>
</s:complexType>
<s:complexTyp e name="SelectMul tipleField">
<s:complexConte nt mixed="false">
<s:extension base="tns:Selec tOneField">
<s:attribute name="maximum_c hoices" type="s:int" use="required"
/>
<s:attribute name="minimum_c hoices" type="s:int" use="required"
/>
</s:extension>
</s:complexConten t>
</s:complexType>

I put in dummy elements as suggested, like this

<s:element minOccurs="0" maxOccurs="1" name="dummy"
type="s:string" />

wherever there was a sequence with only 1 type. That changed the resulting
file,
but the deserialization still didn't give me the choices.

Am I still missing something? How can I catch the exception during
deserialization that
you describe, to see if I am having the same problem? Is this a known bug?

Thanks again,

-- Greg

[Josh Twist]

The XmlSerializer can deal with choices ok - though the code
interpretation is a little messy:
http://msdn.microsoft.com/msdnmag/is...3/06/XMLFiles/

How did you generate your schema?

Josh
http://www.thejoyofcode.com/

[Rémy]

"Greg Allen" <ga****@arrayin c.com> a écrit dans le message de news:
OT************* *@tk2msftngp13. phx.gbl...

OK, here's the relevant section from the WSDL file:

<s:complexTyp e name="FormSecti on">
<s:sequence>
<s:element minOccurs="0" maxOccurs="unbo unded" name="field"
type="tns:FormF ield" />
</s:sequence>
</s:complexType>
<s:complexTyp e name="FormField ">
<s:sequence>
<s:element minOccurs="0" maxOccurs="unbo unded" name="value"
type="s:string" />
</s:sequence>
<s:attribute name="type" type="tns:FormF ieldType" use="required" />
</s:complexType>
<s:simpleType name="FormField Type">
<s:restrictio n base="s:string" >
<s:enumeratio n value="boolean" />
<s:enumeratio n value="select1" />
<s:enumeratio n value="selectn" />
</s:restriction>
</s:simpleType>
<s:complexTyp e name="BooleanFi eld">
<s:complexConte nt mixed="false">
<s:extension base="tns:FormF ield">
<s:sequence>
<s:element minOccurs="0" maxOccurs="1" name="fields"
type="tns:Array OfFormField" />
</s:sequence>
</s:extension>
</s:complexConten t>
</s:complexType>
<s:complexTyp e name="ArrayOfFo rmField">
<s:sequence>
<s:element minOccurs="0" maxOccurs="unbo unded" name="field"
nillable="true" type="tns:FormF ield" />
</s:sequence>
</s:complexType>
<s:complexTyp e name="SelectOne Field">
<s:complexConte nt mixed="false">
<s:extension base="tns:FormF ield">
<s:sequence>
<s:element minOccurs="0" maxOccurs="1" name="choices"
type="tns:Array OfChoice" />
</s:sequence>
</s:extension>
</s:complexConten t>
</s:complexType>
<s:complexTyp e name="ArrayOfCh oice">
<s:sequence>
<s:element minOccurs="0" maxOccurs="unbo unded" name="choice"
nillable="true" type="tns:Choic e" />
</s:sequence>
</s:complexType>
<s:complexTyp e name="Choice">
<s:sequence>
<s:element minOccurs="0" maxOccurs="1" name="value"
type="s:string" />
<s:element minOccurs="0" maxOccurs="1" name="fields"
type="tns:Array OfFormField" />
</s:sequence>
</s:complexType>
<s:complexTyp e name="SelectMul tipleField">
<s:complexConte nt mixed="false">
<s:extension base="tns:Selec tOneField">
<s:attribute name="maximum_c hoices" type="s:int" use="required"
/>
<s:attribute name="minimum_c hoices" type="s:int" use="required"
/>
</s:extension>
</s:complexConten t>
</s:complexType>

I put in dummy elements as suggested, like this

<s:element minOccurs="0" maxOccurs="1" name="dummy"
type="s:string" />

wherever there was a sequence with only 1 type. That changed the
resulting file,
but the deserialization still didn't give me the choices.

There is maybe another problem then ?
You should try to run your code in debugger an try to trace where the
deserialization fails.
Am I still missing something? How can I catch the exception during
deserialization that
you describe, to see if I am having the same problem? Is this a known
bug?

I have seen the exception when running in debugger. It seems to be catched
before returning to our code.

I don't know if it's a known bug (or a misunderstandin g on my side) ...
Thanks again,

-- Greg

[Greg Allen]

I've think I've found a workaround, which may point to the actual problem.

If I change this:

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class FormSection {
[System.Xml.Seri alization.XmlEl ementAttribute( "field")]
public FormField[] field;
}

to this:

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace="http://mywebservice.co m/1.0")]
public class FormSection {
[System.Xml.Seri alization.XmlEl ementAttribute( "field")]
public SelectMultipleF ield[] field;
}

It deserializes correctly!

It seems to have something to do with the inheritance. SelectMultipleF ield
is
the "top most" in the inheritance chain.

And I don't appear to be getting an exception raised during deserialization .
I've tried
to catch it, but it doesn't appear that anything is being thrown.

Does this maybe shed some light on what the real problem might be?

-- Greg