Query beans are optional but they provide a nice way to write queries with
compile time checking. They are also easy to use and learn with
on properties and expressions.
Query beans are generated using a Java annotation processing (APT) or Kotlin annotation processing (KAPT).
For each entity a query bean is generated with the same name but prefixed with
So for an entity bean called Customer there is a query bean generated called QCustomer.
When the entity bean model changes the query beans are regenerated and as developers we get compile time checking on our application queries - we get a compile time error if our queries are no longer valid for the model.
Contact contact = new QContact() // Contact query bean .email.equalTo("firstname.lastname@example.org") // type safe expression .findOne(); // with IDE auto-completion
List<Customer> customers = new QCustomer() // Customer query bean .status.equalTo(Status.NEW) .billingAddress.city.equalTo("Auckland") // joins automatically added .contacts.isEmpty() // to support expressions .findList();
APT / KAPT (generating query beans)
Java query beans we use the io.ebean:querybean-generator
java annotation processor and to generate
Kotlin query beans we use
Generating with Maven
Refer to docs / getting-started / maven for details of how to generate query beans using maven.
Generating with Gradle
Refer to docs / getting-started / gradle for details of how to generate query beans using gradle.
Note that prior to version 12.1.8 we need to edit a
manifest file to specify
querybean-packages for the packages that should
be enhanced for query beans. This is no longer needed from 12.1.8 onwards.
Example (Pre 12.1.8)
entity-packages: org.example.domain transactional-packages: org.example querybean-packages: org.example
Refactor rename entity bean
When we refactor rename an entity bean in an IDE the query beans we should trigger a
This is because the query beans for the old bean names are kept around until the next
Once we do a
build all this will effectively delete the old query beans and generate the new ones.
At this point we get compiler errors for the queries that we need to adjust (use the new query bean names).