CODEWITHSUNDEEP
springspring-data-jpajpqljpa-criteria
user8421021
user8421021

Reputation:

How to display data from multiple tables using Spring data JPA - many to many relation

I am trying to get data from multiple tables in Spring Data JPA.

I have:

Professor.java

@Entity
public class Professor {

    @Id
    @GeneratedValue(strategy = GenerationType.TABLE)
    private Long id;
  private String username;

    private String password;

    private String firstname;

    private String lastname;

//Generated getters and setters

  @ManyToMany(mappedBy = "professors", fetch = FetchType.EAGER, cascade = { CascadeType.MERGE, CascadeType.PERSIST })
    private List<Classes> classes;

Classes.java

@Entity
public class Classes {

    @Id
    @GeneratedValue(strategy = GenerationType.TABLE)
    private Long id;

    private String name;

    @Lob
    private String description;

 @ManyToMany(fetch = FetchType.LAZY, cascade = { CascadeType.MERGE, CascadeType.PERSIST })
    private List<Professor> professors;

These entities generate table named as 'classes_professor' and fields as following classes_id and professor_id

I am trying to display professor with some ID that has been given class with some ID.

ClassesRepository.java

@Repository
public interface ClassesRepository extends CrudRepository<Classes,Long>{

    @Query("SELECT p FROM Professor p join p.Classes c WHERE c.id =:id")
    public List<Professor> findProfessorNameById(@Param("id") long id);
}

Controller.java

public List<Professor> findProfessorNameById(@Param("id") long id){
        return classesRepository.findProfessorNameById(id);
    }

When I try to run it I have this error:

could not resolve property: Classes of: com.oggi.model.Professor [SELECT p FROM com.oggi.model.Professor p join p.Classes c WHERE c.id =:id]

Upvotes: 0

Views: 4290

Answers (1)

Matt
Matt

Reputation: 116

The error lies in p.Classes. It should rather be p.classes since the attribute in your Professor POJO is written in lowercase.

The Query checks the attributes of the Professor POJO / Entity; it does not look for other Entity names.

On top: Sometimes your are writing "profesor" other times "professor".

Upvotes: 2

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