Attaching OVS to model attribute.

[Former Member]

Hi,

Can I attach OVS to a model attribute in the view controller? I tried to do it but at runtime I got the error 'must not modify the datatype of a mapped attribute'. Any suggestions...Thanks.

[Former Member · Accepted solution]

Kapil,

Create non-model calculated attribute, wich getter/setter merely delegates call to original one. If you do not using structure binding, then you may create it in desired model node, otherwise create a subnode (non-model, cardinality=1..1, selection=1..1, initializeLeadSelection=true, singleton=false[actually, it depends]). Then you can apply OVS extension to this attribute.

VS

[Former Member · Accepted solution]

Hi Valery,

Thanks for your suggestion. I will try out your solution shortly.

So, basically does that mean we cannot attach OVS to model attributes in view context?

[Former Member · Accepted solution]

Kapil,

It seems to be so. Neither to model attribute, nor to mapped attribute (when mapping of context controllers used).

VS

[Former Member · Accepted solution]

Hi Valery,

I tried OVS with a non Model attribute and it worked fine.

Can you please explain what do you mean by delegation in your statement 'Create non-model calculated attribute, wich getter/setter merely <b>delegates</b> call to original one'.

I have to attach OVS to a table column. This table is attached through controller to the model for its data.

[Former Member · Accepted solution]

Say you have model node MyNode and model attribute MyAttr. Next you are creating read-write calculated attribute MyCalculus under the same node. WD generates 2 method for this attribute: getter to read value and setter to write value.

So under deleagtion I mean the following:

inside getMyNodeMyCalculus write:

return element.getMyAttr();

inside setMyNodeMyCalculus write:

element.setMyAttr(value);

So in fact you are just proxing original attribute. But your calculated attribute has no metadata / type-data mapping (to model or other controller). Therefore you may use OVS for this calculated attribute.

VS

[Former Member · Accepted solution]

Hi Valery,

Thanks so much for your explanation. As per your suggestion, I was able to attach the OVS help to the table fields by using a calculated attribute. However, as soon as I click on the icon to initiate the OVS help it gives me a NullPointerException as below. I am trying to resolve it, but if you could throw any pointers on how to resolve it, it would be great.

java.lang.NullPointerException

at com.sap.tc.webdynpro.progmodel.valuehelp.NodeCMIModelClassWrapper.<init>(NodeCMIModelClassWrapper.java:46)

at com.sap.tc.webdynpro.progmodel.valuehelp.NodeSingletonCMIModelClassWrapper.<init>(NodeSingletonCMIModelClassWrapper.java:35)

[Former Member · Accepted solution]

I was able to resolve the NullPointerException error.

Another issue : the model attribute is delegated to the calculated attribute but how can I display multiple model attribute values as a single calculated attribute in my table view. The value node is also 1:1.

Thanks Valery!

PS : I was able to resolve this by refering to the parent element.

Message was edited by: kapil sharma

[Former Member · Accepted solution]

Search SDN articles, there was an excelent article by Bertram Ganz regarding calculated attributes with EVS, most of the features could be applied to OVS as well.

VS

[Former Member · Accepted solution]

Hi Guys,

i have also the same NullPointerException in a Webdynrpo App using a RFC Model.

Actually, i'm not a expert in this technology

@Kalpi

So, what you mean by reffering to parent element?

Can you give me an example?

Actually i fight with this problem until three days, and i've no solution.

I hope someone can help me! I became totally desperate.

Thanks

Best Regards,

Chris

Message was edited by: Christian Kleinschroth

Message was edited by: Christian Kleinschroth