How to return DTO - spring

Question

There is a select which returns:
current_id -> integer
current_date -> date
current_position -> character_varying (255)
current_relevant_url -> character_varying (255)
current_restrictions_probability -> character_varying (255)
current_url_changed -> character_varying (255)
current_identifier_id -> integer
phrase_id -> integer
previous_id -> integer
previous_date -> date
previous_position -> character_varying (255)
previous_relevant_url -> character_varying (255)
previous_restrictions_probability -> character_varying (255)
previous_url_changed -> character_varying (255)
previous_identifier_id -> integer
Here it is:
#Query(value = """
select
current.id as current_id,
current.date as current_date,
current.position as current_position,
current.relevant_url as current_relevant_url,
current.restrictions_probability as current_restrictions_probability,
current.url_changed as current_url_changed,
current.identifier_id as current_identifier_id,
current.phrase_id as phrase_id,
previous.id as previous_id,
previous.date as previous_date,
previous.position as previous_position,
previous.relevant_url as previous_relevant_url,
previous.restrictions_probability as previous_restrictions_probability,
previous.url_changed as previous_url_changed,
previous.identifier_id as previous_identifier_id
from (
select
id,
date,
position,
relevant_url,
restrictions_probability,
url_changed,
identifier_id,
phrase_id
from overoptimisation
where identifier_id = :currentOveroptimisationIdentifierId) current
left join (
select
id,
date,
position,
relevant_url,
restrictions_probability,
url_changed,
identifier_id,
phrase_id
from overoptimisation
where identifier_id = :previousOveroptimisationIdentifierId) previous
on current.phrase_id = previous.phrase_id
""",
nativeQuery = true)
List<OveroptimisationDto> report(#Param("previousOveroptimisationIdentifierId") Integer previousOveroptimisationIdentifierId,
#Param("currentOveroptimisationIdentifierId") Integer currentOveroptimisationIdentifierId);
DTO:
#Getter
#Setter
public class OveroptimisationDto {
Integer currentId;
Date currentDate;
String currentPosition;
String currentRelevantUrl;
String currentRestrictionsProbability;
String currentUrlChanged;
Integer currentIdentifierId;
Integer phraseId;
Integer previousId;
Date previousDate;
String previousPosition;
String previousRelevantUrl;
String previousRestrictionsProbability;
String previousUrlChanged;
Integer previousIdentifier_id;
}
Error:
org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap] to type [com.example.marketing3.arsenkin.dtos.OveroptimisationDto]
Have I made a mistake somewhere in naming?

Answer 1

As mentioned in #Jens answer, you should create an interface for projection.
public interface Overoptimisation {
Integer getCurrentId();
Date getCurrentDate();
String getCurrentPosition();
String getCurrentRelevantUrl();
String getCurrentRestrictionsProbability();
String getCurrentUrlChanged();
Integer getCurrentIdentifierId();
Integer getPhraseId();
Integer getPreviousId();
Date getPreviousDate();
String getPreviousPosition();
String getPreviousRelevantUrl();
String getPreviousRestrictionsProbability();
String getPreviousUrlChanged();
Integer getPreviousIdentifier_id();
}
Then you should call to your method like:
#Query(value = "
select
current.id as current_id,
current.date as current_date,
current.position as current_position,
current.relevant_url as current_relevant_url,
current.restrictions_probability as current_restrictions_probability,
current.url_changed as current_url_changed,
current.identifier_id as current_identifier_id,
current.phrase_id as phrase_id,
previous.id as previous_id,
previous.date as previous_date,
previous.position as previous_position,
previous.relevant_url as previous_relevant_url,
previous.restrictions_probability as previous_restrictions_probability,
previous.url_changed as previous_url_changed,
previous.identifier_id as previous_identifier_id
from (
select
id,
date,
position,
relevant_url,
restrictions_probability,
url_changed,
identifier_id,
phrase_id
from overoptimisation
where identifier_id = :currentOveroptimisationIdentifierId) current
left join (
select
id,
date,
position,
relevant_url,
restrictions_probability,
url_changed,
identifier_id,
phrase_id
from overoptimisation
where identifier_id = :previousOveroptimisationIdentifierId) previous
on current.phrase_id = previous.phrase_id",
nativeQuery = true)
List<Overoptimisation> report(#Param("previousOveroptimisationIdentifierId") Integer previousOveroptimisationIdentifierId,
#Param("currentOveroptimisationIdentifierId") Integer currentOveroptimisationIdentifierId);

Answer 2

There is no DTO class support in Spring Data JPA, but you may use an interface as return type and it should work just fine.

Answer 3

Just an addition:
Actually there are 3 types of projections in Spring Sata JPA:
Interface-based Projections (that used above)
Class-based Projections (DTOs)
Dynamic Projections
You can read more about them and how to use here