/*
* #%L
* Nazgul Project: nazgul-core-persistence-api
* %%
* Copyright (C) 2010 - 2017 jGuru Europe AB
* %%
* Licensed under the jGuru Europe AB license (the "License"), based
* on Apache License, Version 2.0; you may not use this file except
* in compliance with the License.
*
* You may obtain a copy of the License at
*
* http://www.jguru.se/licenses/jguruCorporateSourceLicense-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* #L%
*
*/
package se.jguru.nazgul.core.persistence.api.helpers;
import se.jguru.nazgul.core.algorithms.api.Validate;
import se.jguru.nazgul.core.persistence.api.PersistenceOperationException;
import se.jguru.nazgul.core.persistence.model.NazgulEntity;
import se.jguru.nazgul.tools.validation.api.exception.InternalStateValidationException;
import javax.persistence.EntityManager;
import javax.persistence.Query;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import java.util.List;
import java.util.Map;
/**
* Utility methods to simplify JPA Query usage and increase its usability.
*
* @author <a href="mailto:lj@jguru.se">Lennart Jörelid</a>, jGuru Europe AB
*/
public final class QueryOperations {
/**
* Hide constructor for utility classes.
*/
private QueryOperations() {
// Do nothing
}
/**
* Acquires a T-type Entity using the provided primary key.
*
* @param entityType The type of Entity expected.
* @param entityManager The active EntityManager.
* @param primaryKey The primary key used to acquire the Entity.
* @param <T> The type of Entity expected.
* @return The Entity of type T with the provided primaryKey.
* @throws PersistenceOperationException if a JPA-related exception occurred while performing the operation.
*/
public static <T extends NazgulEntity> T findByPrimaryKey(final Class<T> entityType,
final EntityManager entityManager,
final Object primaryKey)
throws PersistenceOperationException {
try {
return JpaOperations.validateInternalState(entityManager.find(entityType, primaryKey));
} catch (InternalStateValidationException e) {
throw new PersistenceOperationException("Found invalid NazgulEntity", e);
}
}
/**
* Fires a JPA NamedQuery, returning the results as a List.
*
* @param query The name of the JPA NamedQuery to fire.
* @param entityManager The active EntityManager.
* @param parameters The parameters for the NamedQuery.
* @param <T> The type of Entity expected.
* @return The List of resulting Entities.
* @throws PersistenceOperationException if a JPA-related exception occurred while performing the operation.
*/
public static <T extends NazgulEntity> List<T> fireNamedQuery(final String query,
final EntityManager entityManager,
final Object... parameters)
throws PersistenceOperationException {
// Delegate and return
return fireNamedQueryWithResultLimit(query, entityManager, Integer.MIN_VALUE, parameters);
}
/**
* Fires a JPA NamedQuery, returning the results as a List.
*
* @param query The name of the JPA NamedQuery to fire.
* @param entityManager The active EntityManager. Cannot be {@code null}.
* @param parameters The parameters for the NamedQuery, assuming that the named query contains
* named parameters matching the key values within the supplied parameters Map.
* @param <T> The type of Entity expected.
* @return The List of resulting Entities.
* @throws PersistenceOperationException if a JPA-related exception occurred while performing the operation.
*/
public static <T extends NazgulEntity> List<T> fireNamedQuery(final String query,
final EntityManager entityManager,
final Map<String, Object> parameters)
throws PersistenceOperationException {
// Delegate
return fireNamedQuery(query, entityManager, Integer.MIN_VALUE, parameters);
}
/**
* Fires a JPA NamedQuery, returning the maximum given results as a List.
*
* @param query The name of the JPA NamedQuery to fire.
* @param entityManager The active EntityManager. Cannot be {@code null}.
* @param parameters The parameters for the NamedQuery.
* @param maxResults The maximum number of results returned. Must not be a negative number.
* @param <T> The type of Entity expected.
* @return The List of resulting Entities.
* @throws PersistenceOperationException if a JPA-related exception occurred while performing the operation.
*/
@SuppressWarnings("unchecked")
public static <T extends NazgulEntity> List<T> fireNamedQueryWithResultLimit(final String query,
final EntityManager entityManager,
final int maxResults,
final Object... parameters)
throws PersistenceOperationException {
// Check sanity
final Query namedQuery = getQuery(query, entityManager, maxResults);
setParameters(namedQuery, parameters);
// All done.
return fireQuery(namedQuery);
}
/**
* Fires a JPA NamedQuery, returning the maximum given results as a List.
*
* @param query The name of the JPA NamedQuery to fire.
* @param entityManager The active EntityManager. Cannot be {@code null}.
* @param parameters The parameters for the NamedQuery, assuming that the named query contains
* named parameters matching the key values within the supplied parameters Map.
* @param maxResults The maximum number of results returned. Must not be a negative number.
* @param <T> The type of Entity expected.
* @return The List of resulting Entities.
* @throws PersistenceOperationException if a JPA-related exception occurred while performing the operation.
*/
public static <T extends NazgulEntity> List<T> fireNamedQuery(final String query,
final EntityManager entityManager,
final int maxResults,
final Map<String, Object> parameters)
throws PersistenceOperationException {
final Query namedQuery = getQuery(query, entityManager, maxResults);
// Assign the supplied parameters.
for (Map.Entry<String, Object> entry : parameters.entrySet()) {
namedQuery.setParameter(entry.getKey(), entry.getValue());
}
// Fire the query; no null Lists are returned.
return fireQuery(namedQuery);
}
/**
* Assigns the supplied indexed JPQL parameters to the supplied query.
*
* @param query The Query whose indexed parameters should be set.
* @param params The parameters to set.
*/
public static void setParameters(final Query query,
final Object... params) {
// Assign all parameters, if any.
if (params != null) {
for (int i = 0; i < params.length; i++) {
// Bump the parameter index value with
// 1, to comply with JDBC...
query.setParameter((i + 1), params[i]);
}
}
}
//
// Private helpers
//
/**
* Retrieves a JPA Query from the supplied EntityManager, sporting the supplied maxResults.
*
* @param query The JPA NamedQuery to fire.
* @param entityManager The active EntityManager. Cannot be {@code null}.
* @param maxResults Either a positive integer, or {@code Integer.MIN_VALUE} to indicate that the max result
* value should not be set.
* @return The JPA NamedQuery with the supplied name.
*/
private static Query getQuery(@NotNull @Size(min = 1) final String query,
@NotNull final EntityManager entityManager,
final int maxResults) {
// Check sanity
Validate.notEmpty(query, "query");
Validate.notNull(entityManager, "entityManager");
// Create the query, and handle the amount of results returned.
Query namedQuery = entityManager.createNamedQuery(query);
if (maxResults != Integer.MIN_VALUE) {
namedQuery.setMaxResults(maxResults);
}
// All done.
return namedQuery;
}
@SuppressWarnings("unchecked")
private static <T extends NazgulEntity> List<T> fireQuery(final Query namedQuery) {
// Fire the query; no null Lists are returned.
List<T> toReturn = (List<T>) namedQuery.getResultList();
for (T current : toReturn) {
// Validate each NazgulEntity.
try {
JpaOperations.validateInternalState(current);
} catch (InternalStateValidationException e) {
throw new PersistenceOperationException("NazgulEntity state validation failed", e);
}
}
// All done.
return toReturn;
}
}