[jira] Commented: (AXIS-2155) Cannot distinguish "element not present" and "element present and nil"

["Juha Kononen (JIRA)" <ax...@ws.apache.org>]

    [ http://issues.apache.org/jira/browse/AXIS-2155?page=comments#action_12330673 ] 

Juha Kononen commented on AXIS-2155:
------------------------------------

Hi,

here's my email which I sent to the axis-user mail list.

"I have a problem with developing an Axis-based system which should be prepared for missing elements and null values.
My schema is prepared for that by using the minOccurs="0" and maxOccurs="1" attributes (I think it's a better solution than using nillable attributes).
But it seems that Axis (1.2.1 Final) don't make any difference between these attributes. 
WSDL2Java creates an elemField.setMinOccurs(0) statement when minOccurs="0" is used but
nothing when minOccurs="1" or greater. Is this a bug?
Isn't Axis should give an error if I did't sent a particular element required by the schema? Or is there something I don't understand?"

Would it possible if Axis just checked (against the schema) whether the xml structure sent can be without particular elements or not (by checking, for example, the minOccurs="0" and minOccurs="1" attributes)?
So if I don't send a particular element which must be sent in according to the schema Axis will give an error message. 
On the other hand, if I send an element without any subelements (in according to the schema) the equivalent classes of those subelements are simply nulls and it's easy to make null checks in server-side code.
Where do we actually need nillable attributes if we can just drop off the elements we don't want to sent? 

I hope I am talking about the same thing :)

Thanks

Juha


> Cannot distinguish "element not present" and "element present and nil"
> ----------------------------------------------------------------------
>
>          Key: AXIS-2155
>          URL: http://issues.apache.org/jira/browse/AXIS-2155
>      Project: Apache Axis
>         Type: Bug
>   Components: Serialization/Deserialization
>     Versions: 1.2.1
>  Environment: Windows XP
>     Reporter: Peter Wisnovsky
>     Priority: Critical
>  Attachments: simple_axis.zip
>
> I have a web service where I need to distinguish between "a value was not sent" and "a value was sent and is nil", both to and from the server. If I have an element of a complex type with a subelement where nillable="true" and minOccurs="0" AXIS generates the attribute of the Java class, but there seems to be no way to indicate for
> <xs:complexType name="ResourceType">
> <xs:complexContent>
> <xs:extension base="pvOperational:PersonType">
> <xs:sequence>
> ..
> <xs:element name="employerRef" type="pvOperational:AgencyReferenceType" minOccurs="0" nillable="true"/>
> that I want no employerRef or a nil employerRef, e.g.
> <resource>
> <employerRef xsi:nil="true"/>
> </resource>
> versus
> <resource/>
> In either case all I see in the proxy is an attribute employerRef that might or might not be null.
> Is this supported? JaxRPC is admittedly unclear on the point as the only issue it discusses is the use of Java holder classes for primitives for either minOccurs=0 OR nillable=true and does not discuss minOccurs=0 AND nillable=true, but it seems pretty fundamental if you are dealing with database-based services to have null indicators.

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