optional nillable values

[Phil Lee]

Hi,

I have added an optional nillable element to a schema like this -
....
<xs:element minOccurs="0" maxOccurs="1" name="Id" type="xs:int"
nillable="true"/>
....
A class is generated from this using xsd.exe and which is used by a web
service where it makes it's way into the wsdl as:

<s:element minOccurs="0" maxOccurs="1" name="Id" nillable="true"
type="s:int" />
Now when the client consumes the web service I get a class

class Thing
{
[System.Xml.Serialization.XmlElementAttribute(IsNul lable=true)]
public System.Nullable<int> Id;

[System.Xml.Serialization.XmlIgnoreAttribute()]
public bool IdSpecified {

}

Which is what I expected. Now however if I specify

Thing t = new Thing();
t.Id = 1;
t.IdSpecified = true;

and send this to the web service it is received as Id=1, IdSpecified=false
which is not what I expected.

Similarly when data is retrieved from the web service the IdSpecified is
always false even if there's data in Id.

I would really expect to be able to optionally send a value or a null value.

Regards
Phil Lee

[Martin Honnen]

Phil Lee wrote:

I have added an optional nillable element to a schema like this -
...
<xs:element minOccurs="0" maxOccurs="1" name="Id" type="xs:int"
nillable="true"/>
...
A class is generated from this using xsd.exe and which is used by a web
service where it makes it's way into the wsdl as:

<s:element minOccurs="0" maxOccurs="1" name="Id" nillable="true"
type="s:int" />

You might want to ask in
microsoft.public.dotnet.framework.aspnet.webservic es for web service
related stuff.

--

Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/

[Kevin Yu [MSFT]]

Hi Phil,

I think you can modify the IdSpecified method like the following:

[System.Xml.Serialization.XmlIgnoreAttribute()]
public bool IdSpecified {
if(this.Id.HasValue)
return true;
else
return false;
}

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[Phil Lee]

Kevin,

ok, thanks. I don't like modifying auto-generated code though - it tends to
get overwritten.

Is this a bug? Or do I not understand nillable correctly - which is quite
possible.

I understood or hoped that nillable meant that an explicit 'nil' value could
be sent to represent a null. Which is different from not sending the
element. So I would expect to be able to:
1) not send the element which would result in the Specified flag being
false
2) send the element with a value which would result in the flag being
true and the value being non-null
3) send the element with a nil-value which would result in the flag
being true and the value being null
which would then be represented quite nicely by a System.Nullable<> and a
FieldSpecified flag.

Regards
Phil Lee

"Kevin Yu [MSFT]" <v-****@online.microsoft.com> wrote in message
news:mO**************@TK2MSFTNGXA02.phx.gbl...

Hi Phil,

I think you can modify the IdSpecified method like the following:

[System.Xml.Serialization.XmlIgnoreAttribute()]
public bool IdSpecified {
if(this.Id.HasValue)
return true;
else
return false;
}

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[Kevin Yu [MSFT]]

Hi Phil,

Thanks for your feedback. Yes, it seems to be a bug, with my search. You
can check the following link for detail.

http://lab.msdn.microsoft.com/Produc...x?feedbackid=c
1dbdc79-db80-4cc1-b392-e6f6e457db85

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[Phil Lee]

Kevin,

I think what I'm asking is slightly different from the "bug" you refer to.

If I have this class/schema:

....
<xs:element minOccurs="0" maxOccurs="1" name="Id" type="xs:int"/>
....

class Customer
{
public int Id;
[XmlIgnore()]
public bool IdSpecified;
}

I can use it like this:

Customer test = new Customer();
test.Id = 2;
test.IdSpecified = true;

now send it somewhere via xml serialization and it arrives with Id=2 and
IdSpecified=true. Note there isn't any special code to set the specified
flag to true when
the Id field is set. It just happens as part of the deserialization
process.

If I have this (nillable value):

....
<xs:element minOccurs="0" maxOccurs="1" name="Id" type="xs:int"
nillable="true"/>
....

class Customer
{
public int? Id;
[XmlIgnore()]
public bool IdSpecified;
}

And I use it in the same way:

Customer test = new Customer();
test.Id = 2;
test.IdSpecified = true;

If I send it somewhere via xml serialization it arrives with Id=2 and
IdSpecified=false which is wrong. The specified flag is always false after
deserialization
regardless of the value of Id and of the specified flag before
serialization.

Look at these examples:

Value being sent before serialization: IdSpecified=true, Id=null
Serialized xml: <Customer> <Id
xsi:null="true" /> </Customer>
Deserialized: IdSpecified=false, Id=null

Value being sent before serialization: IdSpecified=false, Id=null or any
non-null value
Serialized xml: <Customer> </Customer>
Deserialized: IdSpecified=false, Id=null

Value being sent before serialization: IdSpecified=true, Id=4
Serialized xml: <Customer> <Id>4</</Id>
</Customer>
Deserialized: IdSpecified=false, Id=4

The serialized xml is what I would expect. The deserialized data is wrong
because there is no way to distinguish a missing (optional) value from an
explict null value.

Regards
Phil

"Kevin Yu [MSFT]" <v-****@online.microsoft.com> wrote in message
news:Cj**************@TK2MSFTNGXA02.phx.gbl...

Hi Phil,

Thanks for your feedback. Yes, it seems to be a bug, with my search. You
can check the following link for detail.

http://lab.msdn.microsoft.com/Produc...x?feedbackid=c
1dbdc79-db80-4cc1-b392-e6f6e457db85

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."

[Kevin Yu [MSFT]]

Hi Phil,

It seems to have something to do with the web service. I suggest you try to
post it in the web service newsgroup. Maybe there will be more
professionals who can answer this question there.

Kevin Yu
=======
"This posting is provided "AS IS" with no warranties, and confers no
rights."