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Merge pull request #5655 from asturcon/string-cast-jpa 

BAEL-2239 - JPA error "java.lang.String cannot be cast to [Ljava.lang.String;"
This commit is contained in:
Loredana Crusoveanu 2018-11-11 10:21:25 +02:00 committed by GitHub
parent 861df15d2e f7135b4a40
commit f92c0f8794
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5 changed files with 172 additions and 0 deletions
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44
persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/stringcast/DummyEntity.java Normal file
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@ -0,0 +1,44 @@
package com.baeldung.jpa.stringcast;
import javax.persistence.*;
@SqlResultSetMapping(name = "textQueryMapping", classes = {
@ConstructorResult(targetClass = DummyEntity.class, columns = {
@ColumnResult(name = "text")
})
})
@Entity
@Table(name = "dummy")
public class DummyEntity {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String text;
public DummyEntity() {
}
public DummyEntity(String text) {
this.text = text;
}
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
}

41
persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/stringcast/QueryExecutor.java Normal file
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@ -0,0 +1,41 @@
package com.baeldung.jpa.stringcast;
import com.sun.istack.internal.Nullable;
import javax.persistence.EntityManager;
import javax.persistence.Query;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
public class QueryExecutor {
public static List<String[]> executeNativeQueryNoCastCheck(String statement, EntityManager em) {
Query query = em.createNativeQuery(statement);
return query.getResultList();
}
public static List<String[]> executeNativeQueryWithCastCheck(String statement, EntityManager em) {
Query query = em.createNativeQuery(statement);
List results = query.getResultList();
if (results.isEmpty()) {
return new ArrayList<>();
}
if (results.get(0) instanceof String) {
return ((List<String>) results)
.stream()
.map(s -> new String[] { s })
.collect(Collectors.toList());
} else {
return (List<String[]>) results;
}
}
public static <T> List<T> executeNativeQueryGeneric(String statement, String mapping, EntityManager em) {
Query query = em.createNativeQuery(statement, mapping);
return query.getResultList();
}
}

15
persistence-modules/java-jpa/src/main/resources/META-INF/persistence.xml
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@ -21,6 +21,21 @@
</properties>
</persistence-unit>
<persistence-unit name="jpa-h2">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<class>com.baeldung.jpa.stringcast.DummyEntity</class>
<properties>
<property name="javax.persistence.jdbc.driver" value="org.h2.Driver" />
<property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test" />
<property name="javax.persistence.jdbc.user" value="sa" />
<property name="javax.persistence.jdbc.password" value="" />
<property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
<property name="hibernate.hbm2ddl.auto" value="create-drop" />
<property name="show_sql" value="true"/>
<property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
</properties>
</persistence-unit>
<persistence-unit name="jpa-db">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<class>com.baeldung.jpa.model.Car</class>

56
persistence-modules/java-jpa/src/test/java/com/baeldung/jpa/stringcast/SpringCastUnitTest.java Normal file
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@ -0,0 +1,56 @@
package com.baeldung.jpa.stringcast;
import org.junit.BeforeClass;
import org.junit.Test;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import java.util.List;
import static org.junit.Assert.assertEquals;
public class SpringCastUnitTest {
private static EntityManager em;
private static EntityManagerFactory emFactory;
@BeforeClass
public static void setup() {
emFactory = Persistence.createEntityManagerFactory("jpa-h2");
em = emFactory.createEntityManager();
// insert an object into the db
DummyEntity dummyEntity = new DummyEntity();
dummyEntity.setText("text");
EntityTransaction tr = em.getTransaction();
tr.begin();
em.persist(dummyEntity);
tr.commit();
}
@Test(expected = ClassCastException.class)
public void givenExecutorNoCastCheck_whenQueryReturnsOneColumn_thenClassCastThrown() {
List<String[]> results = QueryExecutor.executeNativeQueryNoCastCheck("select text from dummy", em);
// fails
for (String[] row : results) {
// do nothing
}
}
@Test
public void givenExecutorWithCastCheck_whenQueryReturnsOneColumn_thenNoClassCastThrown() {
List<String[]> results = QueryExecutor.executeNativeQueryWithCastCheck("select text from dummy", em);
assertEquals("text", results.get(0)[0]);
}
@Test
public void givenExecutorGeneric_whenQueryReturnsOneColumn_thenNoClassCastThrown() {
List<DummyEntity> results = QueryExecutor.executeNativeQueryGeneric("select text from dummy", "textQueryMapping", em);
assertEquals("text", results.get(0).getText());
}
}

16
persistence-modules/java-jpa/src/test/resources/persistence.xml
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@ -17,5 +17,21 @@
<property name="hibernate.show_sql" value="true" />
</properties>
</persistence-unit>
<persistence-unit name="jpa-h2">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<class>com.baeldung.jpa.stringcast.DummyEntity</class>
<properties>
<property name="javax.persistence.jdbc.driver" value="org.h2.Driver" />
<property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test" />
<property name="javax.persistence.jdbc.user" value="sa" />
<property name="javax.persistence.jdbc.password" value="" />
<property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
<property name="hibernate.hbm2ddl.auto" value="create-drop" />
<property name="show_sql" value="true"/>
<property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
</properties>
</persistence-unit>
</persistence>