how to get specific column in Spring JPA? - spring

Question

I can GET below data by findAll() from db
[
{ id : 1,
name : "John",
age : "23",
sex : "male"
},
{ id : 2
...
]
And what I want to do is getting specific data from db like below.
[
{ id : 1,
name : "John"
},
{ id : : 1,
name : "Peter"
}
...
]
so I tried like this.
Repository
#Repository
public interface PersonDAO extends JpaRepository<Person, Integer> {
#Query(value ="select p.id , p.name from person p", nativeQuery = true)
Collection<Object> getPersonIdAndName();
}
Controller
#GetMapping ("/getPersonIdAndName")
public Collection<Object> getPerson() {
return personDAO.getPersonIdAndName();
}
but the result was like this (by postman)
[
[
1,
"John"
],
[
2,
"Peter"
]
....
]
I want a type key : value, not just value,
because I want to fetch this to React.js state.
how can I fix?
I'd appreciate for your help

Answer 1

You need to Use a Projection. Create a new Interface
public interface PersonProjection {
Integer getId();
String getName();
}
After that in you repository use the projection in the return type
#Repository
public interface PersonDAO extends JpaRepository<Person, Integer> {
#RestResource(exported = false)
Query("select p.id, p.name from Person as p")
Collection<PersonProjection> getPersonIdAndName();
}
Alternately, if you want to #Override the findAll() method you can create a customized repository. Here there is a GitHub repo example https://github.com/federicogatti/Spring-Custom-Repository-Example