JPA criteriabuilder case query

Can anyone provide an example of how to write a case query using criteriabuilder?

Solution

The following is a sample case expression using criteriabuilder (this applies to JPA 2):

Hashtable caseTable = new Hashtable(3);
caseTable.put("Bob","Bobby");
caseTable.put("Susan","Susie");
caseTable.put("Eldrick","Tiger");
Expression expression = builder.get("firstName").caseStatement(caseTable,"NoNickname").equal("Bobby");

It generates the following SQL queries:

"CASE t1.firstName WHEN 'Bob' THEN 'Bobby' WHEN 'Susan' THEN 'Susie' WHEN 'Eldrick' THEN 'Tiger' ELSE 'NoNickname' END = 'Bobby'"

For more information, see JPA 2.0 case expressions