svcutil NOT generating specified fields for minOccurs=0

Question

I am generating a client proxy from a webservice using svcutil. The WSDL contains elements that have the attribute minOccurs set to 0

<xsd:element minOccurs="0" name="dateMaxValue" type="xsd:dateTime"></xsd:element>

However the generated DataContract completly ignores this attribute and just create a normal dateMaxValue attribute without any dateMaxValueSpecified attribute

private System.DateTime dateMaxValueField;

When I generate the proxy using option /serializer:XmlSerializer, I get the xxxSpecified properties.

private System.DateTime dateMaxValueField;

private bool dateMaxValueFieldSpecified;

EDIT

For optional field, I want the field not being sent or not being read when they have no values (equivalent of specified=false with XmlSerializer) Currently incoming and outcoming data are set to default values. How can I obtain a similar behaviour with the DataContractSerializer ? Or if it is already there, how can I use it ?

Answer 1

The behaviour you observe is normal: *Specified fields are generated only when using the XmlSerializer.

The DataContractSerializer never generates those Specified field. Instead. it will set the IsRequired property of the DataMember attribute to false (this is the default value of this property, so you won't even see it in the attribute).

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Outgoing messages

You want to omit fields which have no value in outgoing messages. The problem is that DateTime is a value type, which means that even if it is not set, it has a default value of "0001-01-01T00:00:00".

If you don't want to output it in the outgoing message, you can:

• Add the EmitDefaultValue = false property to the DataMember attribute. This will prevent the element from being written at all in the generated xml.
• Alternatively, change the type to DateTime? => this will output something like <dateMaxValueField i:nil="true"/> in your xml document.

Without modifying the proxy, there is no way to do it.

Incoming messages

The same logic applies: you will have no problem receiving messages which omit an element completely (as long as the corresponding property in the proxy class has IsRequired = false). Please note that as DateTime is a value type, you will always have it populated with its default value ("0001-01-01"). If you prefer to receive a null instance, then you need to modify your proxy and use the DateTime? type.

However, if you want to be able to parse a message containing:

<dateMaxValueField></dateMaxValueField>

then I'm afraid there is no way to do it with the DataContractSerializer.

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note: The XmlSerializer allows for greater flexibility in those scenarios (when precise control over the XML is required, for compatibility reasons for instance).