i am using hazelcast 3.6.1 and implementing distinct aggregate functionality using custom mapreduce to get solr facet kind of results.
public class DistinctMapper implements Mapper<String, Employee, String, Long>{
private transient SimpleEntry<String, Employee> entry = new SimpleEntry<String, Employee>();
private static final Long ONE = Long.valueOf(1L);
private Supplier<String, Employee, String> supplier;
public DistinctMapper(Supplier<String, Employee, String> supplier) {
this.supplier = supplier;
}
#Override
public void map(String key, Employee value, Context<String, Long> context) {
System.out.println("Object "+ entry + " and key "+key);
entry.setKey(key);
entry.setValue(value);
String fieldValue = (String) supplier.apply(entry);
//getValue(value, fieldName);
if (null != fieldValue){
context.emit(fieldValue, ONE);
}
}
}
and mapper is failing with NullPointerException. and sysout statement says entry object is null.
SimpleEntry : https://github.com/hazelcast/hazelcast/blob/v3.7-EA/hazelcast/src/main/java/com/hazelcast/mapreduce/aggregation/impl/SimpleEntry.java
Can you point me the issue in the above code ? Thanks.
entry field is transient. This means that it is not serialized, so when DistinctMapperobject is deserialized on hazecalst node, it's value is null.
Removing the transient will solve the NullPointerException.
On the side note:
Why do you need this entry field? It doesn't seem to have any use.
Related
I want to persist an entity. I want to skip it in case it already exists in the datastore. Assume the name field is part of the primary key. Assume p1 exists in the datastore. Only p2 should be inserted. Inserting p1 produces duplicate key exception.
#Entity
public class PersonEntity extends PanacheEntity {
String name;
public PersonEntity(String name){
this.name=name;
}
public static Uni<PersonEntity> findByName(String name) {
return find("name", name).firstResult();
}
}
#QuarkusTest
public class PersonResourceTest {
#Test
#ReactiveTransactional
void persistListOfPersons() {
List<PersonEntity> persons = List.of(new PersonEntity("p1"), new PersonEntity("p2"));
Predicate<PersonEntity> personExists = entity -> {
//How to consume Uni?
Uni<PersonEntity> entityUni = PersonEntity.findByName(entity.name);
//entityUni.onItem().ifNull().continueWith(???);
//include entity in filtered stream
//return true;
//exclude entity from filtered stream
return false;
};
List<PersonEntity> filteredPersons = persons.stream().filter(personExists).toList();
PersonEntity.persist(filteredPersons);
}
}
I can't produce a valid filter predicate. I need a boolean value somehow produced by the person query. But how?
This should serve as a minimum reproducable example.
I'm struggling since a couple of hours trying to get MapStruct generate a valid mapper for JAXB generated classes. The particularity of these classes is that they don't have neither setters nor adders for collections. For example:
#XmlAccessorType(XmlAccessType.FIELD)
#XmlType(name = "IndividualType", propOrder = {"addressTypes","pensionTypes"})
public class IndividualType
{
...
#XmlElement(name = "addressType")
protected List<AddressType> addressTypes;
#XmlAttribute(name = "firstName", required = true)
protected String firstName;
...
public List<AddressType> getAddressTypes()
{
if (addressTypes == null) {
addressTypes = new ArrayList<AddressType>();
}
return this.addressTypes;
}
public String getFirstName()
{
return firstName;
}
public void setFirstName(String value)
{
this.firstName = value;
}
...
}
The class avove have a getter and a setter for attributes (firstName in this example) but for collections (List here) it only has a getter. Hence it's the consumer responsibility to access via getAddressTypes(add (new AddressType(...)).
The MapStruct mapper for such a class is as follows:
#Mapper(collectionMappingStrategy = CollectionMappingStrategy.TARGET_IMMUTABLE, uses = {AddressTypeMapper.class}, unmappedTargetPolicy = ReportingPolicy.IGNORE, componentModel = "spring")
public interface IndividualTypeMapper
{
IndividualType toIndividualType(IndividualEntity individual);
#InheritInverseConfiguration
IndividualEntity fromIndividualType(IndividualType individualType);
}
And the MapStruct generated code is:
#Override
public IndividualEntity fromIndividualType(IndividualType individualType)
{
if ( individualType == null )
return null;
IndividualEntity individualEntity = new IndividualEntity();
individualEntity.setFirstName( individualType.getFirstName() );
...
return individualEntity;
}
In the generated code above, only the properties having a setter get initialized despite the usage of the TARGET_IMMUTABLE strategy.
Any suggestions please ? Of course, a simple constructor would perfectly do but, for some reason, people seems to prefer complicated and nonworking solutions to simple working ones and, consequently, I have to use MapStruct :-(
Many thanks in advance.
Marie-France
The reason why it is not working is due to the fact that you are using CollectionMappingStrategy.TARGET_IMMUTABLE. With that you are basically telling MapStruct my collection targets are immutable and will throw an exception if you try to modify the collection returned by the getter.
I would suggest removing the collectionMappingStrategy and see whether it works without it.
This has baffled me for a while now and I cannot seem to get the grasp of it. I'm using Cell Value Factory to populate a simple one column table and it does not populate in the table.
It does and I click the rows that are populated but I do not see any values in them- in this case String values. [I just edited this to make it clearer]
I have a different project under which it works under the same kind of data model. What am I doing wrong?
Here's the code. The commented code at the end seems to work though. I've checked to see if the usual mistakes- creating a new column instance or a new tableview instance, are there. Nothing. Please help!
//Simple Data Model
Stock.java
public class Stock {
private SimpleStringProperty stockTicker;
public Stock(String stockTicker) {
this.stockTicker = new SimpleStringProperty(stockTicker);
}
public String getstockTicker() {
return stockTicker.get();
}
public void setstockTicker(String stockticker) {
stockTicker.set(stockticker);
}
}
//Controller class
MainGuiController.java
private ObservableList<Stock> data;
#FXML
private TableView<Stock> stockTableView;// = new TableView<>(data);
#FXML
private TableColumn<Stock, String> tickerCol;
private void setTickersToCol() {
try {
Statement stmt = conn.createStatement();//conn is defined and works
ResultSet rsltset = stmt.executeQuery("SELECT ticker FROM tickerlist order by ticker");
data = FXCollections.observableArrayList();
Stock stockInstance;
while (rsltset.next()) {
stockInstance = new Stock(rsltset.getString(1).toUpperCase());
data.add(stockInstance);
}
} catch (SQLException ex) {
Logger.getLogger(WriteToFile.class.getName()).log(Level.SEVERE, null, ex);
System.out.println("Connection Failed! Check output console");
}
tickerCol.setCellValueFactory(new PropertyValueFactory<Stock,String>("stockTicker"));
stockTableView.setItems(data);
}
/*THIS, ON THE OTHER HAND, WORKS*/
/*Callback<CellDataFeatures<Stock, String>, ObservableValue<String>> cellDataFeat =
new Callback<CellDataFeatures<Stock, String>, ObservableValue<String>>() {
#Override
public ObservableValue<String> call(CellDataFeatures<Stock, String> p) {
return new SimpleStringProperty(p.getValue().getstockTicker());
}
};*/
Suggested solution (use a Lambda, not a PropertyValueFactory)
Instead of:
aColumn.setCellValueFactory(new PropertyValueFactory<Appointment,LocalDate>("date"));
Write:
aColumn.setCellValueFactory(cellData -> cellData.getValue().dateProperty());
For more information, see this answer:
Java: setCellValuefactory; Lambda vs. PropertyValueFactory; advantages/disadvantages
Solution using PropertyValueFactory
The lambda solution outlined above is preferred, but if you wish to use PropertyValueFactory, this alternate solution provides information on that.
How to Fix It
The case of your getter and setter methods are wrong.
getstockTicker should be getStockTicker
setstockTicker should be setStockTicker
Some Background Information
Your PropertyValueFactory remains the same with:
new PropertyValueFactory<Stock,String>("stockTicker")
The naming convention will seem more obvious when you also add a property accessor to your Stock class:
public class Stock {
private SimpleStringProperty stockTicker;
public Stock(String stockTicker) {
this.stockTicker = new SimpleStringProperty(stockTicker);
}
public String getStockTicker() {
return stockTicker.get();
}
public void setStockTicker(String stockticker) {
stockTicker.set(stockticker);
}
public StringProperty stockTickerProperty() {
return stockTicker;
}
}
The PropertyValueFactory uses reflection to find the relevant accessors (these should be public). First, it will try to use the stockTickerProperty accessor and, if that is not present fall back to getters and setters. Providing a property accessor is recommended as then you will automatically enable your table to observe the property in the underlying model, dynamically updating its data as the underlying model changes.
put the Getter and Setter method in you data class for all the elements.
I have a custom JSF input component, named inputPeriod, which is designed to input date-periods. Each period has a from and to date. The functionality of the component is achieved with Javascript, which generates a JSON string and submits it to the component. The input component then use a default converter which converts the JSON periods into a list of Period objects and sets them on my managed bean. This all works perfectly.
The source of the problem I am having, is that now I want to use the same component with EJB entities. I have a Banner entity with a one-to-many relationship with a BannerPeriod entity. Each instance of the BannerPeriod entity takes a from (begins) and to (ends) date, exactly like the existing Period object I am using with my input component. I have implemented a new converter for this:
#ManagedBean
#RequestScoped
public class BannerPeriodConverter implements Converter {
#Override
public Object getAsObject(FacesContext fc, UIComponent uic, String str) {
if (str != null) {
Date from = null, to = null;
try {
JSONObject period = new JSONObject(str);
if (period.has("from")) {
from = new Date(period.getLong("from"));
}
if (period.has("to")) {
to = new Date(period.getLong("to"));
}
} catch (JSONException ex) {
throw new ConverterException(ex);
}
BannerPeriod bp = new BannerPeriod();
bp.setBegins(from);
bp.setEnds(to);
return bp;
}
return null;
}
#Override
public String getAsString(FacesContext fc, UIComponent uic, Object o) {
if (o != null && o instanceof BannerPeriod) {
BannerPeriod bp = (BannerPeriod) o;
JSONObject period = new JSONObject();
try {
period.put("from", bp.getBegins() != null ? bp.getBegins().getTime() : (Object) null);
period.put("to", bp.getEnds() != null ? bp.getEnds().getTime() : (Object) null);
} catch (JSONException ex) {
throw new ConverterException(ex);
}
return period.toString();
}
return "";
}
}
The converter works fine with the component. The issue I am having is that when I edit a banner with existing banner periods, the entities lose their primary key. So, when I submit my form, instead of updating existing periods, I either get a duplicate exception or the existing periods are created again, making actual duplicates in the database.
So my question is, what can I do to avoid this? My guess would be that the input component somehow needs to keep the primary key on the existing entities, but how can I best make something like that? At the moment, the input component is completely detached from the entities and my EJB project. The input component is even located in its own JSF project, while the converter above is located in an EJB project. By default the input component works with a plain Period object, which has no primary key at all. It should continue to do so.
Or maybe this should be solved in some other way?
In your getAsObject() you're creating a completely unmanaged instance of BannerPeriod instead of obtaining the one straight from DB via JPA.
BannerPeriod bp = new BannerPeriod();
bp.setBegins(from);
bp.setEnds(to);
return bp;
Persisting it will of course create a new entry in DB as it's unmanaged by JPA.
Basically, you should instead be obtaining the instance from the DB via JPA:
#EJB
private BannerPeriodService service;
public Object getAsObject(FacesContext context, UIComponent component, String value) {
// ...
return service.find(from, to);
}
wherein the BannerPeriodService#find() obtains the desired instance via EntityManager.
But this approach is pretty clumsy. In case of entities from the DB, the canonical approach is to use their technical/natural identifier for this, such as the autogenerated primary key.
E.g. (null/instanceof checks and so on omitted):
#EJB
private BannerPeriodService service;
public Object getAsString(FacesContext context, UIComponent component, Object value) {
Long id = ((BannerPeriod) value).getId();
return id.toString();
}
public Object getAsObject(FacesContext context, UIComponent component, String value) {
Long id = Long.valueOf(value);
return service.find(id);
}
No need to mess up with JSON format. If you actually need them in JSON format for some unclear reason, then you're going in the wrong direction by using a JSF converter for this.
I understand that hitting the DB in a converter is a relatively expensive job. In that case, the OmniFaces SelectItemsConverter may be what you're looking for.
In my Entity class I have a HashMap. Now I'm trying to create a Select of this Map to be able to select on of the objects. So I created following classes:
HorseConverter:
#Named
public class HorseConverter implements Converter{
#EJB
private HorseBean bean;
#Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
return bean.getHorse(Long.valueOf(value));
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
if(!(value instanceof Horse)){
throw new ConverterException(new FacesMessage("Object is not a Horse"));
} else {
Horse h = (Horse) value;
return Long.toString(h.getId());
}
}
}
Race Entity:
public Map<Horse, Integer> getHorses() {
return horses;
}
public void setHorses(HashMap<Horse, Integer> horses) {
this.horses = horses;
}
And my view:
Horse:
<h:selectOneMenu value="#{betController.horse}" converter="#{horseConverter}">
<f:selectItems value="#{raceController.selectedRace.horses}" var="h" itemLabel="#{h.nickName}" itemValue="#{h}"/>
</h:selectOneMenu>
Seems like the value I'm getting isn't an instance of Horse. I checked the following link:
https://stackoverflow.com/tags/selectonemenu/info So it seems that the key is automaticly used as value. But even writing h.key doesn't make a difference.
EDIT:
Here is my hash and equals code from the Horse Entity:
#Override
public int hashCode() {
int hash = 7;
hash = 97 * hash + (int) (this.id ^ (this.id >>> 32));
return hash;
}
#Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final Horse other = (Horse) obj;
if (this.id != other.id) {
return false;
}
return true;
}
You can't use var on a Map value. This specific <f:selectItems> construct works only if you use List<Horse> instead of Map<Horse, Integer>.
public List<Horse> getHorses() {
return horses;
}
If you really want to use a Map, then you should be returning a Map<String, Horse>, where String is the nickname of the Horse.
public Map<String, Horse> getHorses() {
return horses;
}
In case of using a Map value, don't forget to remove the var:
<f:selectItems value="#{raceController.selectedRace.horses}" />
The map's key becomes the option label and the map's value becomes the option value.
Unrelated to the concrete problem, a HashMap is by nature unordered. If you want to show the dropdown items in insertion order, rather use LinkedHashMap.
Have you overriden hashcode() and equals() in your Horse() object?
Your Converter needs equals() overriden in order to work. If you don't do this, only two references to the same instance of Horse() will be equal, rather than two seperate instances that have exactly the same state. Collections create an implicit copy to compare, so you won't have a single instance on the heap in this case.
Don't forget that the argument in the equals() object is Object(), NOT Horse().
If you don't override hashcode(), the hashcode will be different for every instance of Horse. This means that you will struggle to find the right Horse for comparison, even if your Horses are logically equivalent, because again, you'll have more than one instance that you will be comparing in order to find your Horse in your HashMap.
For further information, see this chapter of Effective Java by Joshua Bloch.