java - Spring Data JPA: Query by Example?

Question

Using Spring Data JPA can I do a query by example where a particular entity instance is used as the search criteria?

For example (no pun intended), if I have a Person entity that looks like:

@Entity
public class Person {
  private String firstName;
  private String lastName;
  private boolean employed;
  private LocalDate dob;
  ...
}

I could find all employed persons with a last name of Smith born on January 1, 1977 with an example:

Person example = new Person();
example.setEmployed(true);
example.setLastName("Smith");
example.setDob(LocalDate.of(1977, Month.JANUARY, 1));
List<Person> foundPersons = personRepository.findByExample(example);

Answer 1

This is now possible with Spring Data. Check out http://docs.spring.io/spring-data/jpa/docs/current/reference/html/#query-by-example

Person person = new Person();                         
person.setLastname("Smith");                          
Example<Person> example = Example.of(person);
List<Person> results = personRepository.findAll(example);

Note that this requires very recent 2016 versions

    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-jpa</artifactId>
        <version>1.10.1.RELEASE</version>       
    </dependency>
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-commons</artifactId>
        <version>1.12.1.RELEASE</version>
    </dependency>

see https://github.com/paulvi/com.example.spring.findbyexample