BC4J: Updating calculated attributes

Question

We're working on some web services with BC4J. For querying data, we have various tags which are calculated. I'm looking for the best practice for receiving updates to those calculated values.
For example, the web service needs to work with the <countyFIPSCode> element, which might have a value of 55043. Internally, that might relate to our county_code = 21.
It's easy enough to build a BC4J calculated attribute for countyFIPSCode, and that's perfect for queries. But I'm looking for the best approach for handling an update or insert that has a value for countyFIPSCode.
For example, one way would be to absorb the XML document, find the <countyFIPSCode> element, get the value, call a database function to get my internal county_code, and use it for the update. I can see lots of approaches, though, and I certainly haven't plumbed the depths of what BC4J can do, so I'm wondering what would be best approach.
-- jim

Answer 1

If you allow the transient CountyFIPSCode attribute to be updateable, then in the setCountyFIPSCode() method in the view row class (or optionally at the entity level if you want to enable this CountyFIPSCode->NormalCountyCode mapping), just after invoking the setAttributeInternal() method to set the value of the transient attribute, you can remap the value, then invoke the setCountyCode() method with the remapped value.
How you accomplish the mapping would depend on how many different county-codes there are. If you have an existing stored function that does the mapping, you could just write an expert-mode view object that looks like:
select yourfunction.map_fips_to_county(:0) as county_code from dualThen you can use this VO to set a value for the zero-th bind variable with the value of the FIPS code, then retrieve the value of the "CountryCode" attribute in the resulting row.