Error in the evaluation of expression..." with empty attributes

[Mike Pokraka]

Hi Jake,

This is an elegant and perfectly valid workaround. 

The issue here is that some parts of the system are more tolerant than
others: in a binding, it doesn't matter whether the source is valid or not,
it will simply result in an empty target value. If you are comparing two
values in a condition, both sides must exist and must be valid. 

One other way to do this would be to use an EX (existence check) test in
your condition to make sure your object instance exists. I don't know
offhand whether the system is clever enough to take Boolean shortcuts and
not bother trying to evaluate the second part of an AND if the first one
fails. If it is clever enough, you could combine them:
&OBJ& EX   AND
&OBJ.ATTR& = &SOMEVALUE&

The reason I mentioned my second example (object-object-attribute) is that
this will also fail in a binding. This has more to do with the way the
internals are designed: 

In the case of object-attribute, an uninstantiated object still contains the
object type that it would be when it will be instantiated, it simply doesn't
have a key.

In the case of object-object-attribute, if the "middle" object does not
exist, and empty value is returned when the parent object attribute is
determined. This empty value has no object  type and therefore trying to
evaluate an attribute will result in an error. There are has more to do with
the fact that the system does not know whether the attribute definition even
exists.

Cheers, 
Mike

> -----Original Message-----
> From: sap-wug-bounces at mit.edu [mailto:sap-wug-bounces at mit.edu] On
> Behalf Of Schmidt, Jake (SN)
> Sent: 20 August 2008 19:17
> To: sap-wug at mit.edu
> Subject: RE: Error in the evaluation of expression..." with empty
> attributes
> 
> Akshay,
> 
> To extend on Mike's example I've had this happen at a &ZOBJ1.ATTR&
> (just
> one subtype, not 2).  This was happening on a couple material master
> attributes (BUS1001006) that were created from classification data
> (function module to read those in).  My fix was to use a container
> operation to bind &ZOBJ1.ATTR& into the WF Container as a stand alone
> element.
> At runtime the WF doesn't error out if the WF Container element is
> empty
> as opposed to the object type.
> 
> I've always assumed it had something to do with how our consultant set
> up those virtual attributes.  I've never fixed it since my non-elegant
> work around works.  If your problem is similar and you do fix then
> please share!
> 
> Thanks
> Jake
> Spirit Aerosystems
> WF Dev
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Wed, 20 Aug 2008 13:49:14 +0100
> From: "Mike Pokraka" <wug at workflowconnections.com>
> Subject: RE: Error in the evaluation of expression..." with empty
> 	attributes
> To: "'SAP Workflow Users' Group'" <sap-wug at mit.edu>
> Message-ID: <00fe01c902c3$2853d230$78fb7690$@com>
> Content-Type: text/plain; charset="us-ascii"
> 
> Akshay,
> 
> 
> 
> Most likely your top object is not instantiated. Another option is if
> you're using an attribute of your attribute object then the 'middle'
> object cannot be empty.
> 
> In other words, for a binding like &ZOBJ1.ZOBJ2.ATTR&, both ZOBJ1 and
> ZOBJ2 must be instantiated otherwise WF will error.
> 
> 
> 
> Cheers,
> 
> Mike
> 
> 
> 
> 
> 
> From: sap-wug-bounces at mit.edu [mailto:sap-wug-bounces at mit.edu] On
> Behalf
> Of akshay.bhagwat at wipro.com
> Sent: 20 August 2008 12:37
> To: sap-wug at mit.edu
> Subject: Error in the evaluation of expression..." with empty
> attributes
> 
> 
> 
> Hi All,
> 
> 
> 
> Has anyone seen problems in assigning empty attributes?
> 
> It's working fine in dev: I am using an object attribute with an object
> type in condition step.However once transported to QA its all falling
> apart with "Error in the evaluation of expression ....." .
> 
> Actual message seen in the log is :
> 
> 
> Error in the evaluation of expression '&ZWF_OBJ<???>.ManualApproval&'
> for item '8'
> 
> 
> I guess similar problem was faced by Mike Pokraka .. but I could not
> find answer to the thread..
> 
>  If Mike or anybody has any clue to the same could you pls suggest what
> needs to be done?
> 
> 
> 
> 
> 
> Thanks and Regards,
> 
> Akshay Bhagwat
> 
> SAP Practice
> 
> Wipro Technologies
> 
> ': +91 20 2293 3700 x 3608
> Fax: +91 20 2293 3756
> 
> 
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