I want to map my query result to RequestProjection interface values.
The following code works and return request id and submission date.
I need to return worker name too. I have tried r.worker_name AS workerName and r.worker_name AS worker_name and r.worker_name AS worker.name but none of them works.
How can I select and map worker name?
Query:
SELECT r.id AS id, r.submission_date AS submissionDate
From Request r
WHERE r.id = 1
Projection:
public interface RequestProjection {
Long getId();
Long getSubmissionDate();
Worker getWorker();
interface Worker {
String getName();
}
}
You can do this without native query using the constructor expression, read more here Spring JPA native query with Projection gives "ConverterNotFoundException"
Related
I'm struggling to trying the pagination feature, as described in the reference document.
This is my table schema:
CREATE TABLE cities
(
id int PRIMARY KEY,
name varchar(255),
pref_id int
);
Repository:
public interface CityRepository extends CrudRepository<CityEntity, Integer> {
Page<CityEntity> findAll(Pageable pageable);
// get all cities in the prefecture
Page<CityEntity> findByPrefId(Integer prefId, Pageable pageable);
}
Test code:
Page<CityEntity> allCities = repository.findAll(PageRequest.of(0, 10));
Page<CityEntity> cities = repository.findByPrefId(1, PageRequest.of(0, 10));
findAll works well, but findByPrefId throws the following error:
Incorrect result size: expected 1, actual 10
org.springframework.dao.IncorrectResultSizeDataAccessException: Incorrect result size: expected 1, actual 10
at org.springframework.dao.support.DataAccessUtils.nullableSingleResult(DataAccessUtils.java:100)
at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.queryForObject(NamedParameterJdbcTemplate.java:237)
at org.springframework.data.jdbc.repository.query.AbstractJdbcQuery.lambda$singleObjectQuery$1(AbstractJdbcQuery.java:115)
at org.springframework.data.jdbc.repository.query.PartTreeJdbcQuery.execute(PartTreeJdbcQuery.java:98)
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor$QueryMethodInvoker.invoke(QueryExecutorMethodInterceptor.java:195)
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:152)
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:130)
...
If I change the method signature into List<CityEntity> findByPrefId(Integer prefId, Pageable pageable), it works.
Am I missing something? I'm using the latest version of spring-data-jdbc (2.0.2.RELEASE).
I don't know about the technicality, but this is what I learned from experience.
In your case, if the total number of cities is lesser than the pageable.getPageSize(), then your repository will return a List<>.
But if total number of cities is bigger than the pageable.getPageSize() then your repository will return a Page<>.
Knowing that, this is what I did to work around it.
Long amount = repository.countByPrefId(prefId);
if(pagination.getPageSize()>amount ) {
List<CityEntity> list = repository.findByPrefId(prefId);
} else {
Page<CityEntity> pages = repository.findByPrefId(person, PageRequest.of(0, 10));
}
This also means that in your repository you'll have two differents methods, one with Pageable as a parameter and one with only PrefId as a parameter.
I believe the accepted answer is referring to Spring Data JPA which does work by returning pages based on a count query derived from the custom query OR manually set via countQuery, no reason for the if/else.
However this flat out does not work in Spring Data JDBC.
https://jira.spring.io/browse/DATAJDBC-554
Workaround provided in link but for reference:
interface FooRepository extends PagingAndSortingRepository<FooEntity, Long> {
List<FooEntity> findAllByBar(String bar, Pageable pageable);
Long countAllByBar(String bar);
}
And then combining those 2 queries like this:
List<FooEntity> fooList = repository.findAllByBar("...", pageable);
Long fooTotalCount = repository.countAllByBar("...");
Page<FooEntity> fooPage = PageableExecutionUtils.getPage(fooList, pageable, () -> fooTotalCount);
I want to get data from two tables using web api, but I'm receiving an error.
Here is my code:
public List<tblEmpTask> GettblEmpTasks()
{
var q = (from n in db.tblEmpTasks
join c in db.tblEmployees on n.intEmpCode equals c.intEmpCode
select new
{
n.strTaskName,
n.dtStart,
c.strEmployeeName,
}).ToList();
return q;
}
Here is the error that I'm receiving:
The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'Join'.
and please note that I am using web api. Looking forward to solve this issue.
when selecting an anonymous the function should return List<object>
or instead
use a type to return value such as-
class myType{
string TaskName, //assuming type as string
string dtStart, //assuming type as string
string EmployeeName //assuming type as string
}
and in LinQ query something like -
select new myType{ TaskName=n.strTaskName, dtStart=n.dtStart, EmployeeName=c.strEmployeeName}
and return as List<myType>
Requirement :
Having a query stored in DB with in a query there is a where condition in that its calling a database function.
Using spring MVC I need to get the query, pass the parameter and get the return value.
This is the query:
SELECT COUNT(*)
FROM IncidentHdr ih, IncidentUser iu
WHERE ih.incidentId = iu.incidentHdr.incidentId
AND get_response_team_access (ih.incidentId, :perscode)
Here get_response_team_access is a DB function which returns an integer. Query works fine as we tested in DB using dummy data.
What I tried So far :
#PersistenceContext
private EntityManager em;
#Override
public Long getAlertCount(String queryString, long persCode) throws DataAccessException {
Query q = em.createQuery(queryString);
q.setParameter("perscode", persCode);
return (long) q.getSingleResult();
}
Throws Exception:
ERROR org.hibernate.hql.internal.ast.ErrorCounter - <AST>:1:293: unexpected AST node: (
antlr.NoViableAltException: unexpected AST node: (
To call DB function from JPQL you have to use FUNCTION keyword.
SELECT COUNT(*) FROM IncidentHdr ih,IncidentUser iu
WHERE ih.incidentId = iu.incidentHdr.incidentId
AND FUNCTION('get_response_team_access',ih.incidentId, :perscode)
Use FUNCTION (formerly FUNC) to call database specific functions from
JPQL
Usage:
You can use FUNCTION to call database functions that are not supported
directly in JPQL and to call user or library specific functions.
Source: http://www.eclipse.org/eclipselink/documentation/2.4/jpa/extensions/j_func.htm
So, I've already done this using the standard Spring Data JPA interface which extends PagingAndSortingRepository in order to achieve pagination and sorting for a REST API. The thing is, now I want to achieve the very same thing but now using just vanilla JPA and so far so good I managed to get my API to paginate but the sorting doesn't work at all. Every time I try to set the parameter (from a pageable object using pageable.getSort()) it ends with a query error (either if I just send a string as parameter like "name" or just send the sort object, it shows errors).
Here's some code:
My repo implementation:
#Override
public List<Project> findByAll(Pageable pageable) {
Query query = em.createQuery("SELECT project FROM Project project ORDER BY :sort");
query.setParameter("sort", pageable.getSort());
query.setMaxResults(pageable.getPageSize());
query.setFirstResult(pageable.getPageSize() * pageable.getPageNumber());
return query.getResultList();
}
My service:
#Override
public Page<Project> findAll(Pageable pageable) {
objects = Lists.newArrayList(repository.findByAll(pageable));
PageImpl<Project> pages= new PageImpl<Project>(objects, pageable, repository.count());
return pages;
}
To be clear, I'm filling the Pageable object via URI and from the console I can say it's actually getting the data, so I assume the problem is with the repo.
Edit: This is the error I get when I replace the setParameter("sort", ...) for a hardcoded string aka query.setParameter("sort", "name"):
java.lang.NumberFormatException: For input string: "name"
And I think this method should stand for strings as well. If I use query.setParameter("sort", pageable.getSort()), the error is the same.
The order by cannot be set as a query parameter. Also, the Pageable.getSort().toString() likely won't return a string suitable for use in an order by clause as it will result in a String that represents the Order as property: ORDER, note the colon.
Here are some modifications that will work, assuming Java 8...
String order = StringUtils.collectionToCommaDelimitedString(
StreamSupport.stream(sort.spliterator(), false)
.map(o -> o.getProperty() + " " + o.getDirection())
.collect(Collectors.toList()));
Query query = em.createQuery(
String.format("SELECT project FROM Project project ORDER BY %s", order));
I am trying to get IEnumerable from linq query below. What am I doing wrong?
IEnumerable<DataRow> results =
context.Database.SqlQuery<DataRow>("SELECT * FROM Customer").AsEnumerable();
DataRow class does not have default (parameterless) constructor, so you can't use it as query parameter type. There is no generic constraints on type parameter, and nothing mentioned on MSDN(!), but column map factory will throw exception if parameter type does not have default constructor:
The result type 'System.Data.DataRow' may not be abstract and must
include a default constructor.
Here is a code which throws this exception:
internal static CollectionColumnMap CreateColumnMapFromReaderAndClrType(
DbDataReader reader, Type type, MetadataWorkspace workspace)
{
BindingFlags flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
ConstructorInfo constructor = type.GetConstructor(flags, (Binder) null, Type.EmptyTypes, (ParameterModifier[]) null);
if (type.IsAbstract || (ConstructorInfo) null == constructor && !type.IsValueType)
throw EntityUtil.InvalidOperation(InvalidTypeForStoreQuery((object) type));
// ...
}
BTW Mapping to DataRow makes no sense, even if it would have default public constructor. Because it is not simple primitive type and it does not have properties which match the names of columns returned from the query (yes, mapping uses properties only).
Correct usage of Linq will be
IEnumerable<Customer> results = context.Customers;
That will generate SELECT * FROM Customer query, and map query results to customer entities. If you really want to use raw SQL:
IEnumerable<Customer> results =
context.Database.SqlQuery<Customer>("SELECT * FROM Customers");
I think we were trying to solve the same problem (Google led me here, anyway). I am executing a raw SQL command through SqlQuery<TElement>(string sql, params object[] parameters and wanted to assert individual properties of the results returned from the query in a unit test.
I called the method:
var result = (db.SqlQuery<Customer>("select * from customers").First();
and verified the data it returned:
Assert.AreEqual("John", result.FirstName);
I defined a private class Customer inside my test class (unfortunately, I'm not using Entity Framework):
private class Customer
{
public string FirstName { get; set; }
}
The properties of Customer must match the column names returned in the SQL query, and they must be properties (not just variables of the Customer class. You don't have to create properties for all of the columns returned from the query.