How to return an object through a webmethod

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Fré - 27 Sep 2007 20:52 GMT

Hi,

I'm having some trouble creating my webservice.

I can easaly return simple datatypes like strings, integers,..., but
returning something like an object doesn't seem to work.

I tried putting <Serializable()> _ in the class, but no difference.

It gives the following error:

System.InvalidOperationException: There was an error generating the XML
document. ---> System.InvalidOperationException: clsUpdate cannot be
serialized because it does not have a parameterless constructor.

Could anyone please help me out with this ? I'm using VS2005, language VB.net

Thx,

Frederick

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John Saunders [MVP] - 27 Sep 2007 21:56 GMT

> Hi,
>
[quoted text clipped - 10 lines]
> document. ---> System.InvalidOperationException: clsUpdate cannot be
> serialized because it does not have a parameterless constructor.

The exception gives you the answer. The class doesn't have a parameterless
constructor.

> Could anyone please help me out with this ? I'm using VS2005, language
> VB.net

Public Sub New()
End Sub

Signature

--------------------------------------------------------------------------------
John Saunders | MVP – Windows Server System – Connected System Developer

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Fré - 28 Sep 2007 08:06 GMT

You are right, I've read the error, but somehow i didn't hear the bell ringing.

I adapted my code, but then got another error, telling me I should use
XmlInclude.

I changed the line "<WebMethod()> _" to "<WebMethod(),
XmlInclude(GetType(clsMyClass))> _", and everything works just fine now.

Thanks a lot,

Frederick

> > Hi,
> >
[quoted text clipped - 19 lines]
> Public Sub New()
> End Sub

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How to return an object through a webmethod

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