CODEWITHSUNDEEP
springspring-bootspring-data-jpaspring-data
user2748161
user2748161

Reputation: 89

Can we fetch data using JPA without using primary key

My Table:

Emotion
EID (Primary Key)
user_mood
Latitude
Longitude
uid 
@Entity
public class Emotion
{
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer eId;
    @Column(name = "user_mood")
    private String mood;
    private String latitude;
    private String longitude;
    private String uid;

}

My Interface:

public interface EmotionRepository extends JpaRepository<Emotion, String>{}

When I try to fetch values using uid emotionRepo.findById(uid) I am getting below type mismatch error

Error message:

org.hibernate.TypeMismatchException: Provided id of the wrong type for class mood_sensor.mood_sensor.pojos.Emotion. Expected: class java.lang.Integer, got class java.lang.String

Can I retrieve data using uid or I should use only the primaryKey(Integer) to retrieve data?

Upvotes: 0

Views: 1812

Answers (2)

Matheus
Matheus

Reputation: 3370

Yes, it's possible, but the method findById, from CrudRepository<T, ID> always expect to receive the ID as the argument - see here (be aware that JpaRepository extends from CrudRepository).

You can query by another field in a variety of ways, but as I saw that your use case is pretty simple, I'd suggest you to make use of Spring Data's query creation deriving from the method's name - see here and here

It's really simple, just create a method called findByUid in your EmotionRepository and Spring will take care of the rest by deriving the desired query from the method's name:

public interface EmotionRepository extends JpaRepository<Emotion, Integer> {
    Optional<Emotion> findByUid(String uid);
}

Spring Data will then generate something like the following query:

SELECT e.* FROM Emotion e WHERE e.uid = <the-value>

Now, you can use findByUid method to query using the uid field.

And another fix: change from

EmotionRepository extends JpaRepository<Emotion, String>

to

EmotionRepository extends JpaRepository<Emotion, Integer>

this is because the id from Emotion is of type Integer, not String.

Upvotes: 2

gear4
gear4

Reputation: 844

Inside your JpaRepository (EmotionRepository), you can make a function signature, anmd and the JPA will create a method to fetch whatever data you need.

This doc should help you understand exactly what is happening: http://static.springsource.org/spring-data/data-jpa/docs/1.0.0.M1/reference/html/#jpa.query-methods.query-creation

Upvotes: 0

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