I am trying to relate two tables with spring / hibernate in MYSQL like this
#Table (name = candidatresumeinfo)
public class CandidateResumeInfo implements Serializable
{
List<SelectedResumes> selectedResumes;
.............
..............
#JoinColumn(name = "selectedresumeid")
#OneToMany
public List<SelectedResumes> getSelectedResumes() {
return selectedResumes;
}
public void setSelectedResumes(List<SelectedResumes> selectedResumes) {
this.selectedResumes = selectedResumes;
}
Now ,i got the data in my list correctly( i checked in debug)but the call from server is getting failed which is saying cause:Nullpointer exception .
thanks
You can use OneToMany annotation only on Collections, so you should change the field to Set or List, because hibernate will return multiple result if you use OneToMany. I think you'd like to use ManyToOne annotation here.
ManyToOne means here that you have multiple CandidateResumeInfo for one SelectedResumes.
OneToMany means here that you have multiple SelectedResumes for one CandidateResumeInfo.
This annotation naming can be a bit strange for first time. Hope I helped.
Answer for your comment:
The best way is you declare the relationship both side.
Here is the example:
CandidateResumeInfo.java:
#OneToMany(mappedBy="candidateResumeInfo")
List<SelectedResumes> selectedResumes;
SelectedResumes.java:
#ManyToOne
#JoinColumn(name="candidate_resume_info_id")
CandidateResumeInfo candidateResumeInfo;
Related
I am trying to implement the OneToOne association in JPA and trying to join two tables using spring boot and spring data JPA. I created one spring boot microservice and implemented the one to one association in my model. But when I am running code I am getting the following error ,
Caused by: org.hibernate.AnnotationException: Illegal attempt to map a non collection as a #OneToMany, #ManyToMany or #CollectionOfElement
Here My First model class Users.java is like following,
#Entity
#Table(name = "users")
public class Users implements Serializable {
private static final long serialVersionUID = 9178661439383356177L;
#Id
#Column(name="user_id")
public Integer userId;
#Column(name="username")
public String username;
#Column(name="password")
public String password;
}
And I am testing association by controller using following code,
#GetMapping("/load")
public Users load() {
return (Users) userObj.findAll();
}
Can anyone help to resolve this association issue please ?
This is wrong.
#OneToOne(mappedBy="nuserId")
public Set<UserRoleMapping> roleUserRoleMappingMappingJoin;
}
OneToOne means only one object..right?
See this for mappings understandings.
https://docs.jboss.org/hibernate/orm/3.6/reference/en-US/html/collections.html#collections-persistent
Annotation #OneToOne defines a single-valued association to another entity, and in your case you associate a user to a Set of UserRoleMapping instead of associating it with a single object of that class. Use #ManyToOne annotation
Actually the exception refers to an invalid #OneToMany, #ManyToMany or #CollectionOfElement mapping
and this can only be
#OneToMany()
#JoinColumn(name="nuser_id" , referencedColumnName="nuserId")
public Users nuserId;
If the #OneToMany relation is valid change this at first to
#OneToMany()
#JoinColumn(name="nuser_id" , referencedColumnName="nuserId")
public List<Users> users;
If the #OneToMany relation is NOT valid change this to
#OneToOne()
#JoinColumn(name="nuser_id" , referencedColumnName="nuserId")
public Users users;
I recently asked this question : Spring Mongodb - Insert Nested document?
And found out that Spring-Data-MongoDB does not support such behavior - so now I need a working alternative.
Now - to avoid having you look at the code on another page, I am going to paste it here from the other question... Here are my two POJOs :
#Document
public class PersonWrapper {
#Id
private ObjectId _Id;
#DBRef
private Person leader;
#DBRef
List<Person> delegates;
// Getters and setters removed for brevity.
}
public class Person
{
#Id
private ObjectId _Id;
private String name;
// Getters and setters removed for brevity.
}
Now, what I want to be able to do here - is send up a JSON object in my POST request as follows :
{
"personWrapper":
{
"_Id":"<ID HERE (MIGHT WANT SQL TO GENERATE THIS DURING CREATE>",
"leader":{
"_Id":"<ID HERE (MIGHT WANT SQL TO GENERATE THIS DURING CREATE>",
"name":"Leader McLeaderFace"
},
delegates:[{...},{...},{...}]
}
}
At this point - I would like the SQL side of this to create the individual records needed - and then insert the PersonWrapper record, with all of the right foreign keys to the desired records, in the most efficient way possible.
To be honest, if one of you thinks I am wrong about the Spring-Data-MongoDB approach to this, I would still be interested in the answer - because it would save me the hassle of migrating my database setup. So I will still tag the spring-data-mongodb community here, too.
If I understand well you want to cascade the save of your objects ?
ex : you save a PersonWrapper with some Person in the delegates property and spring data will save PersonneWrapper in a collection and save also the list of Person in another Collection.
It is possible to do that with Spring DATA JPA if you annotate your POJO with the JPA annotation #OneToMany and setup cascade property of this annotation. See this post
However the cascade feature is not available for Spring DATA mongoDB. See documentation .First you have to save the list of Person and then you save PersonWrapper.
Is it possible to publish two different repositories for the same JPA entity with Spring Data Rest?
I gave the two repositories different paths and rel-names, but only one of the two is available as REST endpoint.
The point why I'm having two repositories is, that one of them is an excerpt, showing only the basic fields of an entity.
The terrible part is not only that you can only have 1 spring data rest repository (#RepositoryRestResource) per Entity but also that if you have a regular JPA #Repository (like CrudRepository or PagingAndSorting) it will also interact with the spring data rest one (as the key in the map is the Entity itself).
Lost quite a few hours debugging random load of one or the other. I guess that if this is a hard limitation of spring data rest at least an Exception could be thrown if the key of the map is already there when trying to override the value.
The answer seems to be: There is only one repository possible per entity.
I ended up using the #Subselect to create a second immutable entity and bound that to the second JpaRepsotory and setting it to #RestResource(exported = false), that also encourages a separation of concerns.
Employee Example
#Entity
#Table(name = "employee")
public class Employee {
#Id
Long id
String name
...
}
#RestResource
public interface EmployeeRepository extends PagingAndSortingRepository<Employee, Long> {
}
#Entity
#Immutable
#Subselect(value = 'select id, name, salary from employee')
public class VEmployeeSummary {
#Id
Long id
...
}
#RestResource(exported = false)
public interface VEmployeeRepository extends JpaRepository<VEmployeeSummary, Long> {
}
Context
Two packages in the monolithic application had different requirements. One needed to expose the entities for the UI in a PagingAndSortingRepository including CRUD functions. The other was for an aggregating backend report component without paging but with sorting.
I know I could have filtered the results from the PagingAndSorting Repository after requesting Pageable.unpaged() but I just wanted a Basic JPA repository which returned List for some filters.
So, this does not directly answer the question, but may help solve the underlying issue.
You can only have one repository per entity... however, you can have multiple entities per table; thus, having multiple repositories per table.
In a bit of code I wrote, I had to create two entities... one with an auto-generated id and another with a preset id, but both pointing to the same table:
#Entity
#Table("line_item")
public class LineItemWithAutoId {
#Id
#GeneratedValue(generator = "system-uuid")
#GenericGenerator(name = "system-uuid", strategy = "uuid")
private String id;
...
}
#Entity
#Table("line_item")
public class LineItemWithPredefinedId {
#Id
private String id;
...
}
Then, I had a repository for each:
public interface LineItemWithoutId extends Repository<LineItemWithAutoId,String> {
...
}
public interface LineItemWithId extends Repository<LineItemWithPredefinedId,String> {
...
}
For the posted issue, you could have two entities. One would be the full entity, with getters and setters for everything. The other, would be the entity, where there are setters for everything, but only getters for the fields you want to make public. Does this make sense?
Using Spring Data and Java JPA, I would like to store comment threads in a MYSQL table. The comments are on some chunk of data, and every comment can have any number of child comments (think Reddit). I was wondering if this Java class makes sense to fulfill my needs.
#Entity
public class Comment extends Identified {
// Comment data
#Column(nullable=false)
private String data;
// Parent comment
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(nullable=true)
private Comment parent;
// Sub comments
#OneToMany(fetch=FetchType.EAGER)
#JoinColumn(nullable=true, mappedBy="parent")
private Set<Comment> children;
public Comment() { }
....
To clarify, my main concern regards having both a ManyToOne and OneToMany relationship to the same class. It seems ugly, but also like the only way to express this relationship.
I assure you that your mapping is completely normal, I would even say usual. The two relationships (many-to-one and one-to-many) are realized in DB using different concepts and do not collide. As the relationship is bidirectional, both mappings represent different ends of two different links (one is relation to parent, another is relation to child).
I have entity e.g. Product which aggregates other entities such as Category. Those entities can also aggregate other entities and so on. Now I need to test my queries to database.
For simple CRUD I would create mock of EntityManager. But what if I have more complex query which I need to test for correct functionality. Then I probably need to persist entity (or more of them) and try to retrieve/update, whatever. I would also need to persist all entities on which my Product depends.
I don't like such approach. What is the best way to test such queries?
Thanks for replies.
Update -- example
Lets assume following entity structure
This structure is maintained by JPA implementation. For example Product class would look like this
#Entity
public class Product {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
#ManyToOne
private Category category;
#ManyToOne
private Entity1 something;
}
So now if I want to test any query used in DAO I need to create Product in database, but it is dependent on Category and Entity1 and there is #ManyToOne annotation so values cannot be null. So I need to persist those entities too, but they have also dependencies.
I'm considering pre-creating entities such Category, Entity1 and Entity2 before test using SQL script or dbunit (mentioned by #chalimartines) which would save large amount of code, but I don't know whether it is good solution. I would like to know some best practices for such testing.
you can use #TransactionConfiguration(transactionManager = "transactionManager", defaultRollback = true) as
#ContextConfiguration(locations={"classpath:/path/to/your/applicationContextTest.xml"})
#RunWith( SpringJUnit4ClassRunner.class)
#TransactionConfiguration(transactionManager = "transactionManager", defaultRollback = true)
public class YourClassTest {
#Test
public void test() {
//your crud
}
}
update
You cant set the dependecies to null in order to avoid to persist them
I don't know other way, but for persisting Product and its dependencies you can use testing framework DBunit that helps you setup database data.