I trying to select from database specific column only
public interface ItemRepository extends PagingAndSortingRepository<Item,String> {
#Query("SELECT i.id FROM Item i where i.id =?1")
Optional<Item> getit(String id);
}
But instead of returning Object Item it returns String (the id value).
How Can I return the object? (I can't add any constructors to it)
p.s. if I use nativeQuery it does work.
This query in JQL can be simpler.
#Query("SELECT i FROM Item i where i.id =?1")
Optional<Item> getit(String id);
Or even
#Query("FROM Item where id =?1")
Optional<Item> getit(String id);
However, since you are already using JPA, you don't need to define any method with a #Query annotation.
findById is already defined.
Optional<Item> itemOpt = itemRepository.findById(id);
Related
I am using JPA Specification , need to select specific columns only.
This is the code:
Specification<Item> spec = (root, query, builder) -> {
query.select(root.get("Id"));
Predicate predicate = builder.equal(root.get("Id"), "12345");
return predicate;
};
In log I see that all columns from Item Entity are selected from database.
Is it a bug?
usage:
interface:
public interface Repo extends PagingAndSortingRepository<Item,String>, JpaSpecificationExecutor<Item> {
}
call:
repo.findAll(spec );
JpaSpecificationExecutor is specifically defined to return the entity type. I suspect it is ignoring the .select(root.get("Id")).
Normally you would use Specifications if you have an extremely dynamic set of conditions you are querying by. If you have just a few parameters you need to search by, I would use a derived query, or a named query.
public interface Repo extends PagingAndSortingRepository<Item,String>, JpaSpecificationExecutor<Item> {
#Query("Select i.id from Item i where name=:name")
Long getIdforName(String name);
}
I have multiple aggregate classes, such as Request, Scribe, Candidate, and Exam.
Sample schema:
Request (id, scribe_id, candidate_id, exam_id, status)
Scribe (id, name)
Candidate (id, name)
Exam (id, name, schedule)
As you can see, Request table has references to Scribe, Candidate, and Exam tables.
For one of the requirements, I need to return all requests based on a condition by including all the corresponding details of scribe, candidate, and exam.
For this, the query in my repository class will be similar to the following:
SELECT r.id, r.status, c.name, s.name,
e.schedule, e.name
FROM request r
JOIN candidate c ON r.candidate=c.id
JOIN scribe s ON r.scribe=s.id
JOIN exam e ON r.exam=e.id
WHERE <some-condition>
Now, is there a way to map the result of this query directly to a custom Java object and return the same in Spring Data JDBC?
I believe another alternative is to use the Spring JDBC template.
Curious, any out-of-the-box support from Spring Data JDBC?
Thanks.
I am able to return custom Java object by setting rowMapperClass value of org.springframework.data.jdbc.repository.query.Query annotation. For this need to define RowMapper for custom Java object.
Changes look similar to the following:
public class RequestResourceRowMapper implements RowMapper<RequestResource> {
#Override
public RequestResource mapRow(ResultSet resultSet, int rowNumber) throws SQLException { ... }
}
In repository class, need to set rowMapper value.
#Query(value = """
SELECT r.id, r.status, c.name, s.name,
e.schedule, e.name
FROM request r
JOIN candidate c ON r.candidate=c.id
JOIN scribe s ON r.scribe=s.id
JOIN exam e ON r.exam=e.id
WHERE <some-condition>
""",
rowMapperClass = RequestResourceRowMapper.class)
List<RequestResource> searchRequestResources(...);
This could have even been possible without using a custom row mapper as well, but in that case, you will have to assign different names to the columns across the tables. You could have defined a simple class and defined all the fields in there and for mapping the java fields with the corresponding columns in the table, you could have used the #Column attributes example:
public class RequestData {
#Column("id")
private Integer requestId;
#Column("scribe_id")
private String scribeId;
#Column("candidate_id")
private Integer candidateId;
#Column("scribe_name")
private String scribeName;
#Column("candidate_name")
private String candidateName;
#Column("exam_name")
private String examName;
#Column("exam_schedule")
private String examSchedule;
}
However, for such case, you need to have different column names across the schema's which might not be possible in your case as you have same column names in multiple schemas.
I am trying to get the result of one query using Spring Data JPA. Here I am sending some parameter and receiving result according to that.
My repository query is,
#Query("select u.username,p.pname from Users u join u.priviJoin p where u.username = :uname AND p.pname = :pname")
List<Users> findByUsername(#Param("uname") String uname , #Param("pname") String pname );
And calling from controller like the following,
#RequestMapping(value = "/joinResult", method = RequestMethod.GET)
public List<Users> joinResultShow()
{
return (List<Users>) userRepo.findByUsername("test_user","testRole");
}
Here we can see that if I am passing some value then only checking according to that parameter. Here I need to modify my query like if parameter is null, then not need to use AND condition in query.
How can I modify this query for avoiding AND condition if parameter is null? I am new to Spring Data JPA world.
Here are some possible options for you
1. Create multiple methods in your repository like
#Query("select u.username,p.pname from Users u join u.priviJoin p where u.username = :uname AND p.pname = :pname")
List<Users> findByusernamewithRole(#Param("uname") String uname , #Param("pname") String pname );
#Query("select u.username,p.pname from Users u join u.priviJoin p where u.username = :uname")
List<Users> findByUsernameWithoutRole(#Param("uname") String uname);
Write a custom respository and use EntityManager. With this you can create a dynamic queries based on your input using CriteriaBuilder and use this criteria in querying.
Last and the most preferred option in case of dynamic inputs(like you have) is Querydsl.
Some articles about querydsl
http://www.baeldung.com/querydsl-with-jpa-tutorial
http://www.querydsl.com/static/querydsl/latest/reference/html/ch02.html
public List<Series> findSeries(int period, String fieldname, int num) {
TypedQuery<Series> query = em.createQuery(
"select s from Series s where s.period = ?1 order by ?2",
Series.class);
query.setParameter(1, period);
query.setParameter(2, fieldname);
query.setMaxResults(num);
return query.getResultList();
}
This is the method I am using. I think order by isn't even getting executed, it doesn't give any error even when I pass incorrect fieldname.
When it comes to dynamic limit and ordering, its best to use PagingAndSortingRepository so now my Repository extends this repository. I can simply use JPA criteria query as below.
If u want to learn more about JPA criteria query i found this very helpful http://docs.spring.io/spring-data/data-jpa/docs/1.0.x/reference/html/#jpa.query-methods.query-creation
#Repository
public interface SeriesRepository extends PagingAndSortingRepository<Series,Long>{
List<Series> findByPeriod(int period, Pageable pageable);
}
And then when I call this method from my dao i can just instantiate PageRequest which is one of the implementation of Pageable. I can add limit and sorting order to this instance.
public List<Series> getSeriesByFilter(int period, String fieldname, int num) {
Sort sort = new Sort(Sort.Direction.ASC, fieldname);
Pageable pageable = new PageRequest(0, num, sort);
return seriesRepo.findByPeriod(period, pageable);
}
You cannot pass variables as column name in order by.
There is a work around which may help you achieve what you are trying.
public List<Series> findSeries(int period, String fieldname, int num) {
String query = "select s from Series s where s.period = "+period+" order by "+fieldname;
return entityManager.createQuery(query).getResultList();
}
Check this question Hibernate Named Query Order By parameter
There are ways to pass column name in order by in ASP, however I am not able to find anything in Spring or JPA.
"Order By" using a parameter for the column name
http://databases.aspfaq.com/database/how-do-i-use-a-variable-in-an-order-by-clause.html
Using spring data JPA, I am trying to make this sort of query (it is more complex, this is a simple case)
#Query(nativeQuery = true,
value = "SELECT * FROM events WHERE typeId IN (?1)")
List<Event> findEventsByType(List<Integer> types);
When I launch the query, an exception raises:
org.postgresql.util.PSQLException: Can't infer the SQL type to use for an instance of java.util.ArrayList. Use setObject() with an explicit Types value to specify the type to use.
I have tried List < Integer >, Integer[], Object[] and String but it is not working...
Can't I pass list of values?
Which is the best approach to make this sort of queries?
Thanks!
Try taking away the #Query and make the method name:
public List<Event> findByTypeIn(List<Integer> types);
See table 2.2 in the link: http://docs.spring.io/spring-data/jpa/docs/1.2.0.RELEASE/reference/html/
I tried like below and it works for me.
#Query(value = "select * from events where type_id in :types", nativeQuery = true)
List<Event> findEventsByType(#Param("types") List<Integer> types);
#Query(value = "SELECT c from Company c where " +
"c.companyName IN (:company_names)")
List<Company> findCompaniesByName(#Param("company_names") List<String> companyNames);
This is the solution to your problem.
Here I am passing List which contains company names and I am querying DB and storing result in List.
Hope this hepls!
Use JPQL. A native query is or should be passed to the database exactly as you have created the SQL string, and unless your driver can take a serialized collection and understand that the single parameter needs to be interpreted as many, it just won't work. The collection you pass in needs the SQL expanded from (?) to (?, ?,...) based on the number of elements in a collection, and JDBC drivers just are not able to do this, and JPA providers are required to execute the string as is.
A JPQL query allows the JPA provider to create the SQL it needs dynamically based on the list passed in, so it can expand the collection for you.
Try this. It will work for Native Query in SpringBoot JPA:
#Query(value = "SELECT * FROM table WHERE columnName IN (:inputList)" ,
nativeQuery = true)
List<Object> findByObjectList(#Param("inputList") List<Object> inputList);
And also in case of JPA, try the below :
List<Object> findByObjectList(List<Object> inputList)
I know this is a little bit out of context (we use Update and not Select), but this can be usefull for others :
/**
* Update the state of list of entities using their ids
* #param ids request ids
* #param state new state
* #return
*/
#Modifying
#Query(value = "UPDATE AbstractRequest SET state = :state WHERE id IN (:ids)")
int updateStates(#Param("ids") List<Long> ids, #Param("state") InternalRequestStep state);
pass array this way inside IN Clause
#Query(value = "select name from teams where name in :names", nativeQuery = true)
List<String> getNames(#Param("names") String[] names);
Call this way
String[] names = {"testing team","development team"};
List<String> teamtest = teamRepository.getNames(names);
Remove brackets around (?1) parameter. Your query value should look like that:
#Query(value = "SELECT * FROM events WHERE typeId IN ?1")
try querying like this:
#Query(nativeQuery = true,
value = "SELECT * FROM events WHERE typeId = ?1")
List<Event> findEventsByType(List<Integer> types);
did it work?