I was testing Spring Data 1.10.4.RELEASE, following the example in Spring Data Docs http://docs.spring.io/spring-data/jpa/docs/current/reference/html/#projections
and I noticed some issues for which I have 2 questions.
First let's suppose I have these 2 entities:
@Entity
public class Person {
@Id @GeneratedValue
private Long id;
private String firstName, lastName;
@OneToOne
private Address address;
}
@Entity
public class Address {
@Id @GeneratedValue
private Long id;
private String street, state, country;
}
- Question 1:
for the following projections:
interface PersonLimited {
String getFirstName();
AddressLimited getAddress();
}
interface AddressLimited {
String getCountry();
}
when I run findPersonByFirstNameProjectedForLimitedData
interface PersonRepository extends CrudRepository<Person, Long> {
@Query("select p from Person p where p.firstName = ?1")
PersonLimited findPersonByFirstNameProjectedForLimitedData(String firstName);
}
it returns exactly what expected :
{
firstName: 'Homer',
address: {
country: 'USA'
}
}
now if I look into the generated SQL, this is what I have:
SELECT person0_.firstName AS col_0_0_,
address1_.id AS id1_13_,
address1_.street AS street2_13_,
address1_.state AS state3_13_,
address1_.country AS country4_13_
FROM person person0_
LEFT OUTER JOIN address address1_
ON person0_.addressId = address1_.id
WHERE person0_.firstName = ?
The projection for the "Person" entity is selecting only "fistName", which is 100% correct because in the PersonLimited interface I've only defined "getFirstName".
But for the "Address" entity, it selects all the fields, which is wrong because in the AddressLimited interface I've only defined "getCountry", It should only select "country".
The generated query should be something like:
SELECT person0_.firstName AS col_0_0_,
address1_.country AS country4_13_
FROM person person0_
LEFT OUTER JOIN address address1_
ON person0_.addressId = address1_.id
WHERE person0_.firstName = ?
so the question is, why it is not selecting only the "country" field for the Address "entity"? why it needs to select all the fields? is it a bug in Spring?
- Question 2:
for the same projection as above,
when I run findAllPersonsProjectedForLimitedData
interface PersonRepository extends CrudRepository<Person, Long> {
@Query("select p from Person p")
List<PersonLimited> findAllPersonsProjectedForLimitedData();
}
it returns exactly what expected :
[
{
firstName: 'Homer',
address: {
country: 'USA'
}
},
{
firstName: 'Maggie',
address: {
country: 'USA'
}
}
]
now if I look into the generated SQL, this is what I have:
SELECT person0_.id AS id1_18_,
person0_.firstName AS firstName2_18_,
person0_.lastName AS lastName3_18_,
person0_.addressid AS company4_18_
FROM person person0_
SELECT address0_.id AS id1_13_0_,
address0_.street AS street2_13_0_,
address0_.state AS state3_13_0_,
address0_.country AS country4_13_0_
FROM address address0_
WHERE address0_.id = ?
here, the projection for both the Person and the Address entities is selecting all the fields which is wrong, it should only select "firstName" and "country".
The generated query should be something like:
SELECT person0_.firstName AS firstName2_18_
FROM person person0_
SELECT address0_.country AS country4_13_0_
FROM address address0_
WHERE address0_.id = ?
is this the normal behavior, shouldn't select only the fields that we need?
Thanks,
