Develop > Business logic layer > Developing the business logic layer using the BOD command framework > Developing BOD Get services
Add business logic to a search expression
You can add additional business logic to an existing search expression by extending the Fetch command implementation.
Procedure
- Determine the XPath key for the search expression to add additional business logic in the Fetch command. If this is for all searches, then use the default fetch implementation. The XPath key can be determined by looking at the command registry for the configuration of the FetchNounNameCmd interface.
- Extend the Fetch command implementation and in the performExecute() method, add the custom business logic. Then call super.performExecute() to fetch the data or directly call the persistence layer.
- Update the command registry to use this extended implementation.
Related concepts
Business Object Document Get processing pattern