Is it possible to add #NodeEntity (or even #RelationshipEntity) annotation from SpringData Neo4j on an interface or abstact class or their fields? If not, how do you manage these situations?
Definitely you can do that on Abstract classes, and I think it's a good practice in some common cases. Let me give you an example that I'm using in my graph model:
#NodeEntity
public abstract class BasicNodeEntity implements Serializable {
#GraphId
private Long nodeId;
public Long getNodeId() {
return nodeId;
}
#Override
public abstract boolean equals(Object o);
#Override
public abstract int hashCode();
}
public abstract class IdentifiableEntity extends BasicNodeEntity {
#Indexed(unique = true)
private String id;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof IdentifiableEntity)) return false;
IdentifiableEntity entity = (IdentifiableEntity) o;
if (id != null ? !id.equals(entity.id) : entity.id != null) return false;
return true;
}
#Override
public int hashCode() {
return id != null ? id.hashCode() : 0;
}
}
Example of entity idenifiable.
public class User extends IdentifiableEntity {
private String firstName;
// ...
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
}
OTOH, as far as I know, if you annotate an interface with #NodeEntity, those classes who implement the interface DON'T inherite the annotation. To be sure I've made a test to check it and definately spring-data-neo4j throws an Exception because don't recognize the inherited class neither an NodeEntity nor a RelationshipEntity.
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'neo4jMappingContext' defined in class org.springframework.data.neo4j.config.Neo4jConfiguration: Invocation of init method failed; nested exception is org.springframework.data.neo4j.mapping.InvalidEntityTypeException: Type class com.xxx.yyy.rest.user.domain.User is neither a #NodeEntity nor a #RelationshipEntity
Hope it helps
#NodeEntity or #RelationshipEntity needs to be defined on POJO or concrete classes. Think it same as #Entity in Hibernate.
But do you see any valid use case for annotating Interfaces or Abstract Classes?
Related
I'm programming an application Web (Semantic Web) and for storing the triples, using sesame, and for mapping of data alibaba. My question is, that way I have to implement the classes,to that at the base of triplets is store an object as a subclass of another , try interfaces but I got no results , below I present the "entities":
the parent class:
import java.math.BigInteger;
import org.openrdf.annotations.Iri;
#Iri(Parent.NS + "Parent")
public interface Parent {
public static final String NS = "http://www.spelta.ec/ontology/example#";
#Iri(Parent.NS +"code")
BigInteger getCode();
#Iri(Parent.NS +"code")
void setCode(BigInteger code);
#Iri(Parent.NS+"description")
String getDescription();
#Iri(Parent.NS+"description")
void setDescription(String description);
}
The child class:
import java.math.BigInteger;
public class Child implements Parent {
private BigInteger code;
private String description;
#Override
public BigInteger getCode() {
return code;
}
#Override
public void setCode(BigInteger code) {
this.code = code;
}
#Override
public String getDescription() {
return description;
}
#Override
public void setDescription(String description) {
this.description = description;
}
}
to consult the store of triples, should define an instance of the Children class is a subclass of Parent
many thanks
I'm trying to follow the new Cineasts app with SDN 4.0.0.M1 and SpringBoot to learn Spring and Neo4j but I have an error when I try to access the movie url with
curl http://localhost:8080/movies
MappingException: Error mapping GraphModel to instance
I implemented the minimum to get something working so the code is simple but I probably forgot something
the movie class
#NodeEntity
public class Movie {
#GraphId
private Long nodeId;
private String id;
private String title;
public Movie() {
}
public Movie(String id, String title) {
this.id = id;
this.title = title;
}
}
the associated MovieRepository is empty at the moment
public interface MovieRepository extends GraphRepository<Movie> {
}
the MovieController
#Autowired
private MovieRepository movieRepository;
#Autowired
private Session session;
#RequestMapping(value = "/movies/{id}", method = RequestMethod.GET, headers = "Accept=application/json")
public
#ResponseBody
Movie getMovie(#PathVariable String id) {
return IteratorUtil.firstOrNull(findMovieByProperty("id", id));
}
public Iterable<Movie> findMovieByProperty(String propertyName, Object propertyValue) {
return session.loadByProperty(Movie.class, new Property(propertyName, propertyValue));
}
and the main class with database connection
#SpringBootApplication
#EnableNeo4jRepositories("cineasts.repository")
#EnableTransactionManagement
public class CineastsApplication extends Neo4jConfiguration {
public static final int NEO4J_PORT = 7474;
#Bean
public Neo4jServer neo4jServer() {
return new RemoteServer("http://localhost:" + NEO4J_PORT);
}
#Override
public SessionFactory getSessionFactory() {
return new SessionFactory("org.neo4j.cineasts.domain");
}
#Override
#Bean
#Scope(value = "session", proxyMode = ScopedProxyMode.TARGET_CLASS)
public Session getSession() throws Exception {
return super.getSession();
}
public static void main(String[] args) {
SpringApplication.run(CineastsApplication.class, args);
}
}
I started Neo4j and added one record with Neo4j browser
CREATE (m:Movie {id:1, name:'The Matrix'}) return m
when I go to localhost:8080 I can see the json response
{
"_links" : {
"movies" : {
"href" : "http://localhost:8080/movies"
},
"profile" : {
"href" : "http://localhost:8080/alps"
}
}
but it fails to display the movies or http://localhost:8080/movies/1 record I just created. Any idea to fix this or get a more relevant message?
Thanks!
The problem could be the fact that your entity definition does not match that of the node you've created.
The Movie class defines a property id of data type String, and a property title of type String.
The Cypher you used however
CREATE (m:Movie {id:1, name:'The Matrix'}) return m
creates a node with a number id instead of a String id and a name property instead of a title property.
Changing the above to
CREATE (m:Movie {id:'1', title:'The Matrix'}) return m
should fix it.
I encountered some difficulties during playing with neo4j. Firstly, when I try to delete defined #EntityModel, I get an exception (Please, forgive me the quality of pics, the exception messages are also in question title):
My Controller (this is just for testing purpouse):
#Controller
public class HomeController {
#Autowired
PersonRepository personRepository;
#RequestMapping(value="/", method = RequestMethod.GET)
public String loadPage(final Model model, final HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) {
Person person = new Person("My person");
personRepository.save(person);
personRepository.findOne(person.getId());
return "home";
}
}
And model:
#NodeEntity
public class Person {
#GraphId
private Long id;
private String name;
public Person() {}
public Person(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(final String name) {
this.name = name;
}
public Long getId() {
return id;
}
}
Configuration file:
#Configuration
#EnableTransactionManagement
#EnableNeo4jRepositories(basePackages = "com.springapp.mvc.repository")
#ComponentScan({"com.springapp.mvc"})
public class PersistenceConfig extends Neo4jConfiguration {
#Bean
public GraphDatabaseService graphDatabaseService() {
return new SpringRestGraphDatabase("http://localhost:7474/db/data");
}
}
My Repository:
public interface PersonRepository extends GraphRepository<Person> {
#Query("MATCH (n:Person{name: \"{namveValue}\"}) RETURN n;")
Person findByName(#Param("nameValue") final String name);
}
What am I doing wrong? I figured out that perhaps Person should implement org.neo4j.graphdb.Node and this is the source of these exceptions. However, having searched github repos I see that people do not implement this interface in their models. I have not found solution on stackoverflow so far.
Node exists in database but I cannot either delete it or save it. Please, help.
You are trying to see if a node with ID '0' exists as a person. Since the root node hasn't got a '__type__' property, the call will fail. SDN uses this property to determine the entity type of a node.
That being said, the exception seems to be caused by the following line:
if(! personRepository.exists(0L)) {
I created Get/Set HttpContext Session Methods in BaseController class and also Mocked HttpContextBase and created Get/Set methods.
Which is the best way to use it.
HomeController : BaseController
{
var value1 = GetDataFromSession("key1")
SetDataInSession("key2",(object)"key2Value");
Or
var value2 = SessionWrapper.GetFromSession("key3");
GetFromSession.SetDataInSession("key4",(object)"key4Value");
}
public class BaseController : Controller
{
public T GetDataFromSession<T>(string key)
{
return (T) HttpContext.Session[key];
}
public void SetDataInSession(string key, object value)
{
HttpContext.Session[key] = value;
}
}
Or
public class BaseController : Controller
{
public ISessionWrapper SessionWrapper { get; set; }
public BaseController()
{
SessionWrapper = new HttpContextSessionWrapper();
}
}
public interface ISessionWrapper
{
T GetFromSession<T>(string key);
void SetInSession(string key, object value);
}
public class HttpContextSessionWrapper : ISessionWrapper
{
public T GetFromSession<T>(string key)
{
return (T) HttpContext.Current.Session[key];
}
public void SetInSession(string key, object value)
{
HttpContext.Current.Session[key] = value;
}
}
The second one seems the best. Although I would probably write those two as extension methods to the HttpSessionStateBase instead of putting them into a base controller. Like this:
public static class SessionExtensions
{
public static T GetDataFromSession<T>(this HttpSessionStateBase session, string key)
{
return (T)session[key];
}
public static void SetDataInSession<T>(this HttpSessionStateBase session, string key, object value)
{
session[key] = value;
}
}
and then inside the controllers, or helpers, or something that has an instance of HttpSessionStateBase use it:
public ActionResult Index()
{
Session.SetDataInSession("key1", "value1");
string value = Session.GetDataFromSession<string>("key1");
...
}
Writing session wrappers is useless in ASP.NET MVC as the HttpSessionStateBase provided by the framework is already an abstract class which could be easily mocked in unit tests.
Just a little correction for the SetDataInSession method of the latest post. In my opinion, it´s a elegant solution! Thanks Darin Dimitrov.
public static class SessionExtensions
{
public static T GetDataFromSession<T>(this HttpSessionStateBase session, string key) {
return (T)session[key];
}
public static void SetDataInSession(this HttpSessionStateBase session, string key, object value) {
session[key] = value;
}
}
First create this class, and after remember to refer its namespace in the Controller class that will call this methods.
When getting the session value:
string value = Session.GetDataFromSession<string>("key1");
The must be a compatible type with the object persisted in the session.
I have this Service bean:
#Stateless
public class BookService
{
#PersistenceContext(unitName="persistentUnit")
protected EntityManager entityManager;
public BookModel find(Long id) {
return entityManager.find(BookModel.class, id);
}
}
And the backing bean for the Facelet page is:
#ManagedBean(name = "bookBean")
#RequestScoped
public class BookBean implements Serializable
{
#EJB
private BookService bookService;
#ManagedProperty(value="#{param.id}")
private Long id;
private DataModel<BookModel> books;
private BookModel currentBook;
#PostConstruct
public void init() {
if (id == null) {
// UPDATE: Retrieve a list of books.
} else {
// UPDATE: id shouldn't be null here.
// Get detail info about a book using the id
currentBook = bookService.find(id);
}
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public BookModel getCurrentBook() {
return currentBook;
}
public void setCurrentBook(BookModel currentBook) {
this.currentBook = currentBook;
}
}
Why is the value of id always returns null even though the URL returned as bookedit.jsf?id=5418 I don't understand this.
Also, I find the EntityManager#find method quite restrictive in that it only accept a primary key value as the second parameter. What if I want to pass a [hashed] value instead of the primary key. How can I do this with the EntityManager#find method?
P.S. I notice the EntityManager#find requirement is the same for both OpenJPA and EclipseLink implementations. Hmm...
I just tried this in one of my managed beans, and it is working. Here's the relevant code, it's basically the same as yours:
#ManagedBean
#RequestScoped
public class TestBean {
#ManagedProperty(value = "#{param.id}")
private Long prop;
#PostConstruct
public void init() {
System.out.println(prop);
// prints 1234 if I go to the url with http://localhost/page.jsf?1234
}
public Long getProp() {
return prop;
}
public void setProp(Long prop) {
this.prop = prop;
}
}
I'm running this on glassfish 3.1.1. The only thought I had is maybe the injected EJB is somehow messing up the request scope in the ManagedBean?