Parent Child Relationships in VBCs - BC User Property : "Populate Child Data"

Virtual Business Components provide for a nice way of presenting data via WebServices. Each time the VBC is loaded/refreshed in the UI, the integration is triggered behind it, and resulting response appears in the UI. But what if there is a parent child relationship in the data being returned and the requirement is to present each set of the hierarchy in a separate applet ? In normal BCs, the data is pulled from the tables, and if links are provided, the child BC gets refreshed when the parent BC is changed. How can we achieve the same in VBCs ? There is a little unknown BC userproperty “Populate Child Data”, which can be used to achieve this nice effect, without scripting, or repeatedly invoking the webservice. Here is what you do.

 

·         Create the two VBCs and the two applets for them. Also created the BO and View based on the BO.

·         Both the VBCs must refer the same IO,either via the BC userpoperty “Outgoing Integration Object Name”, or the IO name gets hardcoded in the WF.

·         The IO should have two ICs, one for parent level and one for child level in response data. The external names must be correctly populated with the BC names created.

·         Link must be created between parent and child BCs. This BC has to be added in the BO.

 

Now if everything is correctly configured, compile everything and fire up the client application. Navigating to the view will bring the data correctly in the two applets, correctly maintaining the parent child relationship between them. Moving to the next record at parent level will refresh the child level data, as the link is in context.

 

Now go ahead and check out the integration logs for this integration. There is a nice tutorial here.

 

You will find that the webservice integration was actually triggered twice, once for each level of hierarchy. The same request goes out and the same response comes back, so it means double the work. Now :

 

·         Go to the child BC you created. Add a new BC userproperty :

·         In the name column, provide : “Populate Child Data”

·         In the value column, provide : “Y”

 

Compile the BC and load the view again. Data still comes as expected in the UI alright, but if you check the integration logs, you will see that the web service was invoked only once.

 

BC user property “Populate Child Data” doesn’t look documented in bookshelf or supportweb. If you are not happy with this approach, there is a scripting alternative suggested on supportweb here.