info.unterrainer.commons.httpserver.daos.ListQuery Maven / Gradle / Ivy
package info.unterrainer.commons.httpserver.daos;
import java.util.Collections;
import java.util.List;
import java.util.function.Function;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.NoResultException;
import javax.persistence.NonUniqueResultException;
import javax.persistence.TypedQuery;
import info.unterrainer.commons.httpserver.jsons.ListJson;
import info.unterrainer.commons.rdbutils.Transactions;
import info.unterrainer.commons.rdbutils.entities.BasicJpa;
import lombok.AccessLevel;
import lombok.RequiredArgsConstructor;
@RequiredArgsConstructor(access = AccessLevel.PACKAGE)
public class ListQuery {
protected final EntityManagerFactory emf;
protected final QueryInterface builder;
protected V withEntityManager(final Function func) {
if (builder.getEntityManager() == null)
return Transactions.withNewTransactionReturning(emf, em -> func.apply(em));
return func.apply(builder.getEntityManager());
}
/**
* Gets all the rows as a {@link ListJson} as returned by a web-service.
*
* The list contains additional information about the data.
*
* @return a {@link ListJson} containing the rows as specified
*/
public ListJson getListJson() {
return getListJson(0, Long.MAX_VALUE);
}
/**
* Gets all the rows specified by offset and size as a {@link ListJson} as
* returned by a web-service.
*
* The list contains additional information about the data.
*
* @param offset the row-number to start at
* @param size the number-of-rows to return
* @return a {@link ListJson} containing the rows as specified
*/
public ListJson getListJson(final long offset, final long size) {
return withEntityManager(em -> {
ListJson r = new ListJson<>();
r.setEntries(builder.getDao().getList(em, builder.getTypedQuery(em), offset, size));
r.setCount((Long) builder.getCountQuery(em).getSingleResult());
return r;
});
}
/**
* Gets the first row this query returns.
*
* @return the result-row as a JPA
*/
public T getFirst() {
List r = getList(0, 1);
if (r.size() == 1) {
T jpa = r.get(0);
return jpa;
}
return null;
}
/**
* Get the first N rows from this queries' results.
*
* @param count the number of rows to get
* @return the list of the first N result-rows as JPAs
*/
public List getN(final long count) {
return getList(0, count);
}
/**
* Execute a SELECT query that returns a single result-row.
*
* @return the result-row as a JPA
* @throws NoResultException if there is no result
* @throws NonUniqueResultException if more than one result
*/
public T getSingle() {
return withEntityManager(em -> {
TypedQuery typedQuery = builder.getTypedQuery(em);
return typedQuery.getSingleResult();
});
}
/**
* Execute a SELECT query that returns multiple result-rows.
*
* @return the list of result-rows as JPAs
*/
public List getList() {
return withEntityManager(em -> builder.getDao().getList(em, builder.getTypedQuery(em), 0, Long.MAX_VALUE));
}
/**
* Gets all the rows specified by offset and size as a list.
*
* @param offset the row-number to start at
* @param size the number-of-rows to return
* @return a list containing the rows as specified
*/
public List getList(final long offset, final long size) {
return withEntityManager(em -> {
TypedQuery query = builder.getTypedQuery(em);
List list = builder.getDao().getList(em, query, offset, size);
return list;
});
}
/**
* Execute a SELECT query that returns multiple result-rows and reverse the
* order of results.
*
* The reversing-process happens after retrieval of the result, since the whole
* list is going to be transferred anyway.
* The list is reversed using {@code Collections.reverse(list)};
*
* @return the reversed list of result-rows as JPAs
*/
public List getListReversed() {
List l = getList();
Collections.reverse(l);
return l;
}
}