I am using an #Entity with a CrudRepository to create an entry in my MySQL database, and I was wondering at what point the #GeneratedValue(strategy = GenerationType.AUTO) execute and generate the auto increment value?
#Entity
#Table(name = "all_contacts")
public class Contact {
//Ideally this would be set as foreign key to application's user schema
private long userId;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column( name="contactid")
private long contactId;
#NotNull
private String name;
//getters and setters
}
//
public interface ContactRepository extends CrudRepository<Contact, Long> { }
I ask because I want to access the value of the contactId through its getter, but do I have to wait until the ContactRepository.save() is called?
We can't know the new assigned id of that entity prior to executing the SQL INSERT statement.
So, yes you need to ContactRepository.save() or any command that trigger SQL INSERT statement before can get that id. But save is better because it is guaranteed that it will always return ID.
We get the generated value once SQL insert statement is executed. We can't know the value is being assinged before save(). GenerationType.AUTO number generator generates automatic object IDs for entity objects and this generated numeric value is used for primary key field.
#Entity
public class Entity {
#Id #GeneratedValue(strategy=GenerationType.AUTO) int id;
}
Related
I have an entity class and repository. Here I'm trying to execute update query but not working.
How to update Lob column in native query or any another solution on jpa query to update Lob column.
#Entity
#Table(name = "comment")
public class Comment implements Serializable {
#Basic
#Lob
#Column(name="Article_COMMENT", columnDefinition="TEXT")
private String articleComment;
#Basic
#Column(name = "ID_ARTICLE")
private Long articleId;
}
#Repository
public interface commentRepository extends JpaRepository<Comment, Long> {
#Query(value = "UPDATE comment set articleComment=: articleComment WHERE articleId =: articleId", nativeQuery=true)
void updateComment(#Param("articleComment") String articleComment, #Param("articleId") Long articleId );
}
Error:
No results were returned by query.
JpaSystemException thrown with message: could not extract ResultSet; nested exception is org.hibernate.exception.GenericJDBCException: could not extract ResultSet
Your question is very vague so I can answer on assumptions only. I think You want to update the articalComment field of your Entity. You can simply use .save() method of JpaRepository. Your code should be as follows. Here I am also assuming that your articleId is unique identifier to your entity class.
#Entity
#Table(name = "comment")
public class Comment implements Serializable {
#Basic
#Lob
#Column(name="Article_COMMENT", columnDefinition="TEXT")
private String articleComment;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "ID_ARTICLE")
private Long articleId;
}
Now your Id should be unique and has a #Id Annotation to identify it inside spring data JPA.
You don't have to add any code inside of your JPA repository. Simply call commentRepository.save(commentObject) method. If commentObject has an ID as 0 then a new Comment will be created. If the ID is a positive value and is present in your table that particular row will be updated not created.
remove the space try this way
UPDATE comment set articleComment=:articleComment WHERE articleId =:articleId
I have read about the use of #MapsId and #PrimaryKeyJoinColumn annotations, which sounds like a great options. I have two tables (UserList and UserInformation) which have a child, parent relationship, respectively; both classes below are abbreviated to just include the relevant columns. UserInformation's primary key value is always null and does not take the value of its parent column.
User Class
#Entity
#Data
#Table(name = "user_list")
public class UserList {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
// List of foreign keys connecting different entities
#OneToOne(mappedBy = "user")
#MapsId("id")
private UserInformation userInfo;
}
UserInformation Class
#Entity
#Data
#Table(name = "user_information")
public class UserInformation implements Serializable {
#Id
private Integer userId;
#OneToOne
private UserList user;
}
I would prefer to not use an intermediary class if possible. I'm not tied to MapsId or even this implementation if there is a better solution.
Thanks!
The question is not very clear to me, but I think you could improve the following in the modeling of the entity:
The #column annotation can only be omitted when the class parameter is called exactly the same as the database column, taking into account the table name nomenclature, could it be that the column is user_id ?, if so the id parameter should be :
#Id
#column(name="USER_ID")
private Integer userId;
In the user entity being id, it will match the DB ID field so the #column annotation is not necessary
I have two tables. I want to make between them relationship, but the thing is that the child table connects to an attribute in a parent node, which is not a PK. How can I assign a non-PK field as a FK for a table?
Here are the tables. User Information:
#Entity
#Table(name="user")
public class userinformation implements Serializable {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="USER_ID")
private int uID;
#Column(name="LIB_ID")
private String libID;
//Other attributes
}
Lib Information
#Entity
#Table(name="libinfo")
public class Auth {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name="AUTH_ID")
private int authID;
#Column(name="LIB_ID")
private String lib_ID;
//Other attributes
}
They both should be linked through libID (surely unique). Any idea how to implement it correctly?
Given:
class User {
#Column(name = "lib_id")
private String libID;
}
you must map the Auth entity as:
class Auth {
#JoinColumn(name = "lib_id", referencedColumnName = "lib_id")
#ManyToOne
private User user;
}
Basically, referencedColumnName is used to inform the JPA provider that it should use a column other than the primary key column of the referenced entity (which is used by default with #ManyToOne mappings).
I wanna create a compound primary key, one field of which is autogenerated (JPA).
Can I do this ? Is it possible some how to get a generator from spring environment ?
My entity code is
#Entity
#IdClass(value = IntemKey.class)
public class Item implements Serializable {
#Id // wanna autogenerate this field
private Long id;
#Id
private Date add;
private Date del;
....
getter/setter
}
#Embeddable
public class ItemKey implements Serializable {
private Long id;
private Date add = new Date();
...
getter/setter + equals + hashCode
}
table with data
id add del
1 2015.01.01 null
2 2015.01.03 2015.01.05
2 2015.01.05 null
It can be created by Hibernate, check here for more information.
#Id // wanna autogenerate this field
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
*EDIT : * For compound key check this blog post
I have two entity bean :
#Entity
public class User {
#Id
#GeneratedValue
private Long id;
#OneToMany(mappedBy="user", cascade = CascadeType.ALL)
private List<Comment> comments = new ArrayList<Comment>();
//SOME OTHER CLASS VARIABLES
//GETTERS AND SETTERS
}
and my Comment class is like this :
#Entity
public class Comment {
#Id
#GeneratedValue
private Long id;
private String title;
private String content;
#ManyToOne
private User user
//SOME OTHER CLASS VARIABLES
//GETTERS AND SETTERS
}
now I know that I can get the User Object from session and set the user for my comment like this in order to be able to use the join feature in JPA:
commentObject.setUser(TheSessionGrabedUserObject/UserObjectWhichHasFetchedFromDbUsingUserId);
but as long as I have the userId for my user Object I do not need to do this.
I'm looking for a way to insert this foreignKey into my comment table without getting the User Object from session or maybe query to database to fetch it first !
how I'm gonna do it using JPQL ?
You can use the entityManager.getReference() method. In your case:
entityManager.getReference(User.class, userId);
This will not perform any DB query, but will give you a User instance with only the ID populated, and you can pass that to commentObject.setUser().