[appengine-java] NullPointerException at Transaction.commit()
import java.util.List;
import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManager;
import javax.jdo.PersistenceManagerFactory;
import javax.jdo.Transaction;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.Query;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import com.wissen.enterprisebysush.client.GreetingService;
import com.wissen.enterprisebysush.server.domainobject.Department;
import com.wissen.enterprisebysush.server.domainobject.Employee;
/**
* The server side implementation of the RPC service.
*/
@SuppressWarnings("serial")
public class GreetingServiceImpl extends RemoteServiceServlet
implements GreetingService {
EntityManagerFactory emf =
Persistence.createEntityManagerFactory("transactions-optional");
public String greetServer(String input) {
String serverInfo = getServletContext().getServerInfo();
String userAgent = getThreadLocalRequest().getHeader("User-
Agent");
return "Hello, " + input + "!I am running " +
serverInfo + ".It looks like you are using:" + userAgent;
}
@SuppressWarnings("unchecked")
public void addDept(String dept_name, String dept_head) {
EntityManager em = null;
try {
em = emf.createEntityManager();
em.getTransaction().begin();
Department d = new Department();
d.setDept_name(dept_name);
d.setHead(dept_head);
Query q = em.createQuery("select from
com.wissen.enterprisebysush.server.domainobject.Department d");
List deptList = q.getResultList();
for (Department dept : deptList) {
System.out.println("Department name: " +
dept.getDept_name());
}
em.persist(d);
} finally {
em.getTransaction().commit();
em.close();
}
}
public void addEmp(String emp_name, String emp_sal, String did) {
EntityManager em = emf.createEntityManager();
try {
String s = did;
EntityTransaction transaction = em.getTransaction();
transaction.begin();
System.out.println("value of Department_name is::" + s);
System.out.println("Transaction is active and
is::"+transaction);
//Query q = em.createQuery("select dept_id
from com.wissen.enterprisebysush.server.domainobject.Department d
where d.dept_name = ?1");
//q.setParameter(1, s);
//System.out.println("Name of Department is::"
+ s);
//Department dept = (Department)
q.getSingleResult();
Query q = em.createQuery("select from
com.wissen.enterprisebysush.server.domainobject.Department d");
Department dept = (Department) q.getResultList().get(0);
System.out.println("Name of Department is::" +
dept.getDept_name());
//System.out.println("Query executed
Successfully!!" + q.getSingleResult());
Employee e = new Employee();
e.setEmp_name("Abdch");
e.setEmp_sal("5000");
e.setDepartment(dept);
em.persist(e);
System.out.println("Transaction: " + transaction);
transaction.commit();
em.close();
} catch (NullPointerException e) {
e.printStackTrace();
System.out.println("Exception::" + e.getCause());
} finally {
}
}
}
output::
value of Department_name is::Production
Transaction is active and
is::org.datanucleus.jpa.entitytransactioni...@1a21c7d
Name of Department is::Accounts
Transaction: org.datanucleus.jpa.entitytransactioni...@1a21c7d
java.lang.NullPointerException
Exception::null at
com.google.appengine.api.datastore.KeyFactory.stringToKey(KeyFactory.java:
181)
at
org.datanucleus.store.appengine.DatastoreElementContainerStoreSpecialization.extractElementKey(DatastoreElementContainerStoreSpecialization.java:
170)
at
org.datanucleus.store.appengine.DatastoreAbstractCollectionStoreSpecialization.contains(DatastoreAbstractCollectionStoreSpecialization.java:
57)
at
org.datanucleus.store.mapped.scostore.AbstractCollectionStore.contains(AbstractCollectionStore.java:
116)
at org.datanucleus.sco.backed.List.contains(List.java:455)
at
org.datanucleus.state.RelationshipManager.processManyToOneBidirectionalRelation(RelationshipManager.java:
690)
at
org.datanucleus.state.RelationshipManager.process(RelationshipManager.java:
294)
at
org.datanucleus.state.JDOStateManagerImpl.processManagedRelations(JDOStateManagerImpl.java:
2377)
at
org.datanucleus.ObjectManagerImpl.performManagedRelationships(ObjectManagerImpl.java:
2706)
at org.datanucleus.ObjectManagerImpl.flush(ObjectManager
[appengine-java] Null Pointer Exception at the time of transaction commit.
package com.wissen.enterprisebysush.server;
import java.util.List;
import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManager;
import javax.jdo.PersistenceManagerFactory;
import javax.jdo.Transaction;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.Query;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import com.wissen.enterprisebysush.client.GreetingService;
import com.wissen.enterprisebysush.server.domainobject.Department;
import com.wissen.enterprisebysush.server.domainobject.Employee;
/**
* The server side implementation of the RPC service.
*/
@SuppressWarnings("serial")
public class GreetingServiceImpl extends RemoteServiceServlet implements
GreetingService {
EntityManagerFactory emf =
Persistence.createEntityManagerFactory("transactions-optional");
public String greetServer(String input) {
String serverInfo = getServletContext().getServerInfo();
String userAgent = getThreadLocalRequest().getHeader("User-Agent");
return "Hello, " + input + "!I am running " + serverInfo +
".It looks like you are using:" + userAgent;
}
@SuppressWarnings("unchecked")
public void addDept(String dept_name, String dept_head) {
EntityManager em = null;
try {
em = emf.createEntityManager();
em.getTransaction().begin();
Department d = new Department();
d.setDept_name(dept_name);
d.setHead(dept_head);
Query q = em.createQuery("select from
com.wissen.enterprisebysush.server.domainobject.Department d");
List deptList = q.getResultList();
for (Department dept : deptList) {
System.out.println("Department name: " +
dept.getDept_name());
}
em.persist(d);
} finally {
em.getTransaction().commit();
em.close();
}
}
public void addEmp(String emp_name, String emp_sal, String did) {
EntityManager em = emf.createEntityManager();
try {
String s = did;
EntityTransaction transaction = em.getTransaction();
transaction.begin();
System.out.println("value of Department_name is::" + s);
System.out.println("Transaction is active and
is::"+transaction);
//Query q = em.createQuery("select dept_id from
com.wissen.enterprisebysush.server.domainobject.Department d where
d.dept_name = ?1");
//q.setParameter(1, s);
//System.out.println("Name of Department is::" + s);
//Department dept = (Department)
q.getSingleResult();
Query q = em.createQuery("select from
com.wissen.enterprisebysush.server.domainobject.Department d");
Department dept = (Department) q.getResultList().get(0);
System.out.println("Name of Department is::" +
dept.getDept_name());
//System.out.println("Query executed Successfully!!"
+ q.getSingleResult());
Employee e = new Employee();
e.setEmp_name("Abcdh");
e.setEmp_sal("5000");
e.setDepartment(dept);
em.persist(e);
System.out.println("Transaction: " + transaction);
transaction.commit();
em.close();
} catch (NullPointerException e) {
e.printStackTrace();
System.out.println("Exception::" + e.getCause());
} finally {
}
}
}
Output is::
The server is running at http://localhost:8090/
value of Department_name is::Production
Transaction is active and
is::org.datanucleus.jpa.entitytransactioni...@1a21c7d
Name of Department is::Accounts
Transaction: org.datanucleus.jpa.entitytransactioni...@1a21c7d
java.lang.NullPointerException
Exception::nullat
com.google.appengine.api.datastore.KeyFactory.stringToKey(KeyFactory.java:181)
at
org.datanucleus.store.appengine.DatastoreElementContainerStoreSpecialization.extractElementKey(DatastoreElementContainerStoreSpecialization.java:170)
at
org.datanucleus.store.appengine.DatastoreAbstractCollectionStoreSpecialization.contains(DatastoreAbstractCollectionStoreSpecialization.java:57)
at
org.datanucleus.store.mapped.scostore.AbstractCollectionStore.contains(AbstractCollectionStore.java:116)
at org.datanucleus.sco.backed.List.contains(List.java:455)
at
org.datanucleus.state.RelationshipManager.processManyToOneBidirectionalRelation(RelationshipManager.java:690)
at
org.datanucleus.state.RelationshipManager.process(RelationshipManager.java:294)
at
org.datanucleus.state.JDOStateManagerImpl.processManagedRelations(JDOStateManagerImpl.java:2377)
at
org.datanucleus.ObjectManagerImpl.performManagedRelationships(ObjectManagerImpl.java:2706)
a
Re: [appengine-java] Null Pointer Exception at the time of transaction commit.
Thanks Stephan Hartmann,
But there is another problem now .
Does the DataStore will have a Foreign Key of Department in Employee?
And , is it visible in the Employee table?
Following are my POJO's ::
/Department///
import java.io.Serializable;
import java.util.List;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import com.google.appengine.api.datastore.Key;
/**
* @author Sushama Khadilkar.
*
* Create Date : 17-Feb-2010
*/
@SuppressWarnings("serial")
@Entity
public class Department implements Serializable{
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Key dept_id;
private String dept_name;
private String head;
@OneToMany(mappedBy="department")
public Listemployee;
public Key getDept_id() {
return dept_id;
}
public void setDept_id(Key dept_id) {
this.dept_id = dept_id;
}
public String getDept_name() {
return dept_name;
}
public void setDept_name(String dept_name) {
this.dept_name = dept_name;
}
public String getHead() {
return head;
}
public void setHead(String head) {
this.head = head;
}
public List getEmployee() {
return employee;
}
public void setEmployee(List employee) {
this.employee = employee;
}
}
//Employee/
import java.io.Serializable;
import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import com.google.appengine.api.datastore.Key;
/**
* @author Sushama Khadilkar.
*
* Create Date : 17-Feb-2010
*/
@SuppressWarnings("serial")
@Entity
public class Employee implements Serializable{
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Key emp_id;
private String emp_name;
private String emp_sal;
@ManyToOne(cascade = CascadeType.ALL)
private Department department;
public Key getEmp_id() {
return emp_id;
}
public void setEmp_id(Key emp_id) {
this.emp_id = emp_id;
}
public String getEmp_name() {
return emp_name;
}
public void setEmp_name(String emp_name) {
this.emp_name = emp_name;
}
public String getEmp_sal() {
return emp_sal;
}
public void setEmp_sal(String emp_sal) {
this.emp_sal = emp_sal;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
}
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Re: [appengine-java] Null Pointer Exception at the time of transaction commit.
Thanks Again Stephan Hartmann,But can u tell me one thing ,
>>
> cant we use List or Set or something else for the return type of the
addEmp() method. because while using Set as a return type in Async
& in greeting Service i m gettin a error. so plz can u tell it me. Plz
Plz.
The output is::
Compiling module com.employeedepartmentgae.Employeedepartmentgae
Refreshing module from source
Validating newly compiled units
Removing units with errors
[ERROR] Errors in
'file:/home/wissen18/employeedepartmentgae/src/com/employeedepartmentgae/client/GreetingServiceAsync.java'
[ERROR] Line 6: The import
com.employeedepartmentgae.server.domainobject.Employee cannot be resolved
[ERROR] Line 18: Employee cannot be resolved to a type
[ERROR] Errors in
'file:/home/wissen18/employeedepartmentgae/src/com/employeedepartmentgae/client/GreetingService.java'
[ERROR] Line 6: The import
com.employeedepartmentgae.server.domainobject.Employee cannot be resolved
[ERROR] Line 20: Employee cannot be resolved to a type
[ERROR] Errors in
'file:/home/wissen18/employeedepartmentgae/src/com/employeedepartmentgae/client/EmployeeWidget.java'
[ERROR] Line 12: The import
com.employeedepartmentgae.server.domainobject.Employee cannot be resolved
[ERROR] Line 75: The method addEmp(String, String, String,
AsyncCallback>) from the type GreetingServiceAsync refers to
the missing type Employee
[ERROR] Line 75: The type new
AsyncCallback>(){} must implement the inherited abstract
method AsyncCallback>.onSuccess(Set)
[ERROR] Line 75: Employee cannot be resolved to a type
[ERROR] Line 94: The method onSuccess(Set) of type
new AsyncCallback>(){} must override or implement a supertype
method
[ERROR] Line 94: Employee cannot be resolved to a type
[ERROR] Line 96: Employee cannot be resolved to a type
[ERROR] Line 96: Employee cannot be resolved to a type
[ERROR] Line 98: Employee cannot be resolved to a type
Removing invalidated units
[WARN] Compilation unit
'file:/home/wissen18/employeedepartmentgae/src/com/employeedepartmentgae/client/Employeedepartmentgae.java'
is removed due to invalid reference(s):
[WARN]
file:/home/wissen18/employeedepartmentgae/src/com/employeedepartmentgae/client/EmployeeWidget.java
[WARN] Compilation unit
'file:/home/wissen18/employeedepartmentgae/src/com/employeedepartmentgae/client/DepartmentWidget.java'
is removed due to invalid reference(s):
[WARN]
file:/home/wissen18/employeedepartmentgae/src/com/employeedepartmentgae/client/GreetingService.java
[WARN]
file:/home/wissen18/employeedepartmentgae/src/com/employeedepartmentgae/client/GreetingServiceAsync.java
Computing all possible rebind results for
'com.employeedepartmentgae.client.Employeedepartmentgae'
Rebinding com.employeedepartmentgae.client.Employeedepartmentgae
Checking rule
[ERROR] Unable to find type
'com.employeedepartmentgae.client.Employeedepartmentgae'
[ERROR] Hint: Previous compiler errors may have made this
type unavailable
[ERROR] Hint: Check the inheritance chain from your module;
it may not be inheriting a required module or a module may not be adding its
source path entries properly
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[appengine-java] Re: NullPointerException at Transaction.commit()
Max, Actually that problem is solved .I completely changed my POJO's and that error is gone . But now i have one more question to you Question How can i send a list of employees in a particular department , because i tried it using Set & List but it is giving me a error . So could you plz tell me how to do that. I have a list of employees in Deparment POJO. -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
Re: [appengine-java] Re: Editing records in datastore (using JAVA)
If you want to update the record using EntityManager , then just use em.merge(Object). This the link to the Example:: http://www.javabeat.net/articles/81-jpa-in-netbeans-61-4.html -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
Re: [appengine-java] Null Pointer Exception at the time of transaction commit.
Thanks, But i'm not getting wat are u saying so can u plz explain clearly... -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
