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Why the Spring's @Query annotation returns Object type?

Spring JPA selecting specific columnsSpring- How to remove a property from a list of Objects?Spring Data JPA: How can Query return Non- Entities Objects or List of Objects?Spring data JPA and parameters that can be nullspring-boot / spring-data-jpa custom query filtering by Date field returning results without filteringReturn custom Object using custom Query with Spring Data JPAHow to Return all instances of the type with the given ID in JPA SpringBoot?not able to execute between date jpa data with query annotation@Query annotation and named parameters in quoted stringsOptional param with query Spring-Boot jpa 1.5JPQL with specific column returning Object arraySpring Data and Oracle returns different result from query? Why?

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0

I have the below query to fetch specific columns of a entity/table from database

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<User> getCredentialsByEmail( @Param("email") String email);

But this gives the ClassCastException, and that's because the query return the Object type instead of User.

Whereas, if I select all the columns as below:

@Query("SELECT u FROM User u WHERE email = :email")
Optional<User> getCredentialsByEmail( @Param("email") String email);

the query return the correct class type i.e User. I don't understand why this difference is provided by the Spring framework.

Any suggestions please.

spring-boot spring-data-jpa

share|improve this question

asked Mar 22 at 18:07

TheCoderTheCoder

506420

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  you may get answer from here stackoverflow.com/questions/22007341/…
  
  – Patel Romil
  Mar 23 at 5:14
  

  
  
  
  

add a comment | 

0

I have the below query to fetch specific columns of a entity/table from database

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<User> getCredentialsByEmail( @Param("email") String email);

But this gives the ClassCastException, and that's because the query return the Object type instead of User.

Whereas, if I select all the columns as below:

@Query("SELECT u FROM User u WHERE email = :email")
Optional<User> getCredentialsByEmail( @Param("email") String email);

the query return the correct class type i.e User. I don't understand why this difference is provided by the Spring framework.

Any suggestions please.

spring-boot spring-data-jpa

share|improve this question

asked Mar 22 at 18:07

TheCoderTheCoder

506420

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  you may get answer from here stackoverflow.com/questions/22007341/…
  
  – Patel Romil
  Mar 23 at 5:14
  

  
  
  
  

add a comment | 

I have the below query to fetch specific columns of a entity/table from database

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<User> getCredentialsByEmail( @Param("email") String email);

But this gives the ClassCastException, and that's because the query return the Object type instead of User.

Whereas, if I select all the columns as below:

@Query("SELECT u FROM User u WHERE email = :email")
Optional<User> getCredentialsByEmail( @Param("email") String email);

the query return the correct class type i.e User. I don't understand why this difference is provided by the Spring framework.

Any suggestions please.

spring-boot spring-data-jpa

share|improve this question

asked Mar 22 at 18:07

TheCoderTheCoder

506420

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<User> getCredentialsByEmail( @Param("email") String email);

@Query("SELECT u FROM User u WHERE email = :email")
Optional<User> getCredentialsByEmail( @Param("email") String email);

share|improve this question

asked Mar 22 at 18:07

TheCoderTheCoder

506420

share|improve this question

asked Mar 22 at 18:07

TheCoderTheCoder

506420

asked Mar 22 at 18:07

TheCoderTheCoder

506420

asked Mar 22 at 18:07

TheCoderTheCoder

506420

2 Answers
2

active

oldest

votes

0

If you required only couple of columns the you can use Object[] object array

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Object[]> getCredentialsByEmail( @Param("email") String email);

From 0 position you can get the email

From 1 position you can get the password

If you like to make it much clear, use Interface

public interface Response 

 public String getEmail();

 public String getPAssword();

Query make sure column names and get names should match, if not you can use allies in query

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Response> getCredentialsByEmail( @Param("email") String email);

share|improve this answer

answered Mar 22 at 18:37

DeadpoolDeadpool

8,4222831

add a comment | 

0

As commented your first query does not return User object but a Tuple containing the selected columns. Tuple is not necessarily tied to any specific entity but just a set of columns your query returns.

There are at least following options how you can handle this:

• make your repo method return a tuple object


• make a DTO for selected columns and instantiate it with new operator


• with new operator make a constructor for your user object that takes selected columns

The last option would be like creating a constructor:

public User(String email, String password ) 
 // set the field values

and query like:

@Query("SELECT NEW some.package.User(u.email u.password) FROM USER u WHERE email = :email")

For more details see this question

share|improve this answer

edited Mar 22 at 18:40

answered Mar 22 at 18:21

pirhopirho

5,164121932

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I cannot use DTOs in the persistence layer. They are all created in Web layer for some reasons. Isn't there any other way(not Tuple)?
  
  – TheCoder
  Mar 22 at 18:30
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @TheCoder see the last option I wrote, creatign User with new operator with a specific constructor. I'll edit the answer a bit.
  
  – pirho
  Mar 22 at 18:36
  

  
  
  
  

add a comment | 

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0

If you required only couple of columns the you can use Object[] object array

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Object[]> getCredentialsByEmail( @Param("email") String email);

From 0 position you can get the email

From 1 position you can get the password

If you like to make it much clear, use Interface

public interface Response 

 public String getEmail();

 public String getPAssword();

Query make sure column names and get names should match, if not you can use allies in query

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Response> getCredentialsByEmail( @Param("email") String email);

share|improve this answer

answered Mar 22 at 18:37

DeadpoolDeadpool

8,4222831

add a comment | 

0

If you required only couple of columns the you can use Object[] object array

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Object[]> getCredentialsByEmail( @Param("email") String email);

From 0 position you can get the email

From 1 position you can get the password

If you like to make it much clear, use Interface

public interface Response 

 public String getEmail();

 public String getPAssword();

Query make sure column names and get names should match, if not you can use allies in query

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Response> getCredentialsByEmail( @Param("email") String email);

share|improve this answer

answered Mar 22 at 18:37

DeadpoolDeadpool

8,4222831

add a comment | 

If you required only couple of columns the you can use Object[] object array

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Object[]> getCredentialsByEmail( @Param("email") String email);

From 0 position you can get the email

From 1 position you can get the password

If you like to make it much clear, use Interface

public interface Response 

 public String getEmail();

 public String getPAssword();

Query make sure column names and get names should match, if not you can use allies in query

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Response> getCredentialsByEmail( @Param("email") String email);

share|improve this answer

answered Mar 22 at 18:37

DeadpoolDeadpool

8,4222831

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Object[]> getCredentialsByEmail( @Param("email") String email);

public interface Response 

 public String getEmail();

 public String getPAssword();

@Query("SELECT u.email, u.password FROM User u WHERE email = :email")
Optional<Response> getCredentialsByEmail( @Param("email") String email);

share|improve this answer

answered Mar 22 at 18:37

DeadpoolDeadpool

8,4222831

answered Mar 22 at 18:37

DeadpoolDeadpool

8,4222831

answered Mar 22 at 18:37

DeadpoolDeadpool

8,4222831

0

As commented your first query does not return User object but a Tuple containing the selected columns. Tuple is not necessarily tied to any specific entity but just a set of columns your query returns.

There are at least following options how you can handle this:

• make your repo method return a tuple object


• make a DTO for selected columns and instantiate it with new operator


• with new operator make a constructor for your user object that takes selected columns

The last option would be like creating a constructor:

public User(String email, String password ) 
 // set the field values

and query like:

@Query("SELECT NEW some.package.User(u.email u.password) FROM USER u WHERE email = :email")

For more details see this question

share|improve this answer

edited Mar 22 at 18:40

answered Mar 22 at 18:21

pirhopirho

5,164121932

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I cannot use DTOs in the persistence layer. They are all created in Web layer for some reasons. Isn't there any other way(not Tuple)?
  
  – TheCoder
  Mar 22 at 18:30
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @TheCoder see the last option I wrote, creatign User with new operator with a specific constructor. I'll edit the answer a bit.
  
  – pirho
  Mar 22 at 18:36
  

  
  
  
  

add a comment | 

0

As commented your first query does not return User object but a Tuple containing the selected columns. Tuple is not necessarily tied to any specific entity but just a set of columns your query returns.

There are at least following options how you can handle this:

• make your repo method return a tuple object


• make a DTO for selected columns and instantiate it with new operator


• with new operator make a constructor for your user object that takes selected columns

The last option would be like creating a constructor:

public User(String email, String password ) 
 // set the field values

and query like:

@Query("SELECT NEW some.package.User(u.email u.password) FROM USER u WHERE email = :email")

For more details see this question

share|improve this answer

edited Mar 22 at 18:40

answered Mar 22 at 18:21

pirhopirho

5,164121932

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I cannot use DTOs in the persistence layer. They are all created in Web layer for some reasons. Isn't there any other way(not Tuple)?
  
  – TheCoder
  Mar 22 at 18:30
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @TheCoder see the last option I wrote, creatign User with new operator with a specific constructor. I'll edit the answer a bit.
  
  – pirho
  Mar 22 at 18:36
  

  
  
  
  

add a comment | 

As commented your first query does not return User object but a Tuple containing the selected columns. Tuple is not necessarily tied to any specific entity but just a set of columns your query returns.

There are at least following options how you can handle this:

• make your repo method return a tuple object


• make a DTO for selected columns and instantiate it with new operator


• with new operator make a constructor for your user object that takes selected columns

The last option would be like creating a constructor:

public User(String email, String password ) 
 // set the field values

and query like:

@Query("SELECT NEW some.package.User(u.email u.password) FROM USER u WHERE email = :email")

For more details see this question

share|improve this answer

edited Mar 22 at 18:40

answered Mar 22 at 18:21

pirhopirho

5,164121932

public User(String email, String password ) 
 // set the field values

@Query("SELECT NEW some.package.User(u.email u.password) FROM USER u WHERE email = :email")

share|improve this answer

edited Mar 22 at 18:40

answered Mar 22 at 18:21

pirhopirho

5,164121932

answered Mar 22 at 18:21

pirhopirho

5,164121932

answered Mar 22 at 18:21

pirhopirho

5,164121932