With jackson, I can use #JsonAnyGetter and #JsonAnySetter to serialize/deserialize a Map<String, Object> into extra fields of a json object. Is there a JPA annotation that will do similar things with extra db column values being get/set from/into a member Map?
Specifically, I'd like to use jooq's .fetchInto(Pojo.class) to hydrate a java object. I can manually use .fetch(RecordMapper<Record, Pojo>) to get the results I want by hydrating the Map member from the Record fields manually, but wondering if there's a more automatic way of doing this. Pojo code could look something like the following (use lombok's #Data to make it concise):
#Data
public class Pojo {
#Column("field1")
private int field1;
#Column("field2")
private String field2;
#JsonAnyGetter // works for json serialization,
#JsonAnySetter // is there an equivalent for JPA?
private Map<String, Object> extraFields;
}
You can register a RecordMapperProvider with your jOOQ configuration in order to override how various methods, including fetchInto(Class) apply mapping:
https://www.jooq.org/doc/3.11/manual/sql-execution/fetching/pojos-with-recordmapper-provider/
Related
I am working with Spring Data 2.0.6.RELEASE.
I am working about pagination for performance and presentation purposes.
Here about performance I am talking about that if we have a lot of records is better show them through pages
I have the following and works fine:
interface PersonaDataJpaCrudRepository extends PagingAndSortingRepository<Persona, String> {
}
The #Controller works fine with:
#GetMapping(produces=MediaType.TEXT_HTML_VALUE)
public String findAll(Pageable pageable, Model model){
Through Thymeleaf I am able to apply pagination. Therefore until here the goal has been accomplished.
Note: The Persona class is annotated with JPA (#Entity, Id, etc)
Now I am concerned about the following: even when pagination works in Spring Data about the amount the records, what about of the content of each record?.
I mean: let's assume that Persona class contains 20 fields (consider any entity you want for your app), thus for a view based in html where a report only uses 4 fields (id, firstname, lastname, date), thus we have 16 unnecessary fields for each entity in memory
I have tried the following:
interface PersonaDataJpaCrudRepository extends PagingAndSortingRepository<Persona, String> {
#Query("SELECT p.id, id.nombre, id.apellido, id.fecha FROM Persona p")
#Override
Page<Persona> findAll(Pageable pageable);
}
If I do a simple print in the #Controller it fails about the following:
java.lang.ClassCastException:
[Ljava.lang.Object; cannot be cast to com.manuel.jordan.domain.Persona
If I avoid that the view fails with:
Caused by:
org.springframework.expression.spel.SpelEvaluationException:
EL1008E:
Property or field 'id' cannot be found on object of type
'java.lang.Object[]' - maybe not public or not valid?
I have read many posts in SO such as:
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to
I understand the answer and I am agree about the Object[] return type because I am working with specific set of fields.
Is mandatory work with the complete set of fields for each entity? Should I simply accept the cost of memory about the 16 fields in this case that never are used? It for each record retrieved?
Is there a solution to work around with a specific set of fields or Object[] with the current API of Spring Data?
Have a look at Spring data Projections. For example, interface-based projections may be used to expose certain attributes through specific getter methods.
Interface:
interface PersonaSubset {
long getId();
String getNombre();
String getApellido();
String getFecha();
}
Repository method:
Page<PersonaSubset> findAll(Pageable pageable);
If you only want to read a specific set of columns you don't need to fetch the whole entity. Create a class containing requested columns - for example:
public class PersonBasicData {
private String firstName;
private String lastName;
public PersonBasicData(String firstName, String lastName) {
this.firstName = fistName;
this.lastName = lastName;
}
// getters and setters if needed
}
Then you can specify query using #Query annotation on repository method using constructor expression like this:
#Query("SELECT NEW some.package.PersonBasicData(p.firstName, p.lastName) FROM Person AS p")
You could also use Criteria API to get it done programatically:
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<PersonBasicData> query = cb.createQuery(PersonBasicData.class);
Root<Person> person = query.from(Person.class);
query.multiselect(person.get("firstName"), person.get("lastName"));
List<PersonBasicData> results = entityManager.createQuery(query).getResultList();
Be aware that instance of PersonBasicData being created just for read purposes - you won't be able to make changes to it and persist those back in your database as the class is not marked as entity and thus your JPA provider will not work with it.
I have a list List<Payment> which I'd like to map to another list List<PaymentPlan>. These types look like this:
public class Payment {
#XmlElement(name = "Installment")
#JsonProperty("Installment")
private List<Installment> installments = new ArrayList<>();
#XmlElement(name = "OriginalAmount")
#JsonProperty("OriginalAmount")
private BigDecimal originalAmount;
//getters setters, more attributes
}
and....
public class PaymentPlan {
//(Installment in different package)
private List<Installment> installments;
#XmlElement(name = "OriginalAmount")
#JsonProperty("OriginalAmount")
private BigDecimal originalAmount;
//getters setters, more attributes
}
I expect that something like this is working...
#Mappings({
#Mapping(//other mappings...),
#Mapping(source = "payments", target = "paymentInformation.paymentPlans")
})
ResultResponse originalResponseToResultResponse(OrigResponse originalResponse);
...but I get:
Can't map property java.util.List<Payment> to java.util.List<PaymentPlan>.
Consider to declare/implement a mapping method java.util.List<PaymentPlan> map(java.util.List<Payment> value);
I don't know how to apply this information. First I though I need to declare some extra mapping (in the same mapper class) for the lists, so MapStruct knows how to map each field of the List types like this:
#Mappings({
#Mapping(source = "payment.originalAmount", target = "paymentInformation.paymentPlan.originalAmount")
})
List<PaymentPlan> paymentToPaymentPlan(List<Payment> payment);
...but I get error messages like
The type of parameter "payment" has no property named "originalAmount".
Obviously I do something completely wrong, since it sound like it does not even recognize the types of the List.
How can I basically map from one List to another similar List? Obviously I somehow need to combine different mapping strategies.
btw: I know how to do it with expression mapping, like...
#Mapping(target = "paymentPlans",expression="java(Helper.mapManually(payments))")
but I guess MapStruct can handle this by iself.
I presume you are using version 1.1.0.Final. Your extra mapping is correct, the only difference is that you need to define a mapping without the lists MapStruct will then use that to do the mapping (the example message is a bit misleading for collections).
PaymentPlan paymentToPaymentPlan(Payment payment);
You don't even need the #Mappings as they would be automatically mapped. You might also need to define methods for the Instalment (as they are in different packages).
If you switch to 1.2.0.CR2 then MapStruct can automatically generate the methods for you.
I can't get an ArrayList to serialize using the AutoBean mechanism. I'm using GWT 2.7. Here is my setup:
public interface IUser {
String getName();
void setName(String name);
ArrayList<String> getFriends();
void setFriends(ArrayList<String> friends);
}
public class User implements IUser {
private String name;
private ArrayList<String> friends;
... getters and setters for all members attributes ...
}
then my bean factory:
public interface AutoBeanFactoryImpl extends AutoBeanFactory {
AutoBean<IUser> user(IUser inst);
}
and finally my usage:
ArrayList<String> friends = new ArrayList<String>();
friends.add("Mary");
User user = new User();
user.setName("Fritz");
user.setFriends(friends);
AutoBeanFactoryImpl factory = GWT.create(AutoBeanFactoryImpl.class);
AutoBean<IUser> bean = factory.user(user);
String json = AutoBeanCodex.encode(bean).getPayload();
The output json does not have the friends array. It has the name ok though. Why doesn't the string array get serialized? Do I need something special for that?
Thanks
The problem is that you specified ArrayList instead of just plain List - in order to nicely generate code that fills in the gaps between Java and JSON, autobeans only want to work with interfaces. Aside from getters and setters, AutoBeans have special support for List, Set (which is just a List without duplicates in the JSON), and Map. If you specify a particular implementation, the AutoBean tooling can't always handle it.
Feel free to pass in an ArrayList instance, but declare your getter and setter to be of type List.
As an aside, those collections can be of any type that AutoBeans can otherwise handle - including numbers, booleans, strings, dates, and any other bean-like interface that also conform to what AutoBeans can deal with.
I met a very strange phenomenon when using dozer in jpa project.
I have a UserSupplier object and a Supplier object.
UserSupplier:
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "supplier_id", nullable = false)
private Supplier supplier;
In my code I first query a UserSupplier List, then convert it to SupplierList.
List<Supplier> supplierList = new ArrayList<>(usList.size());
usList.forEach(us -> supplierList.add(us.getSupplier()));
Then I convert SupplierList to SupplierView List and return it to Caller.
BeanMapper.mapList(supplierList, SupplierView.class);
My dozer configure in these objects like below
Supplier:
#Id
#GeneratedValue
#Mapping("supplierId")
private int id;
SupplierView:
private int supplierId;
Very funny, supplierId in SupplierView always 0(default int value),but other fileds can convert successfully, only id field fail. I don't why is this, why only id field can't convert to supplierId, but other fields could?
For above problem, there are below solutions
1. Change field name (supplierId to id):
Supplier:
// #Mapping("supplierId")
private int id;
SupplierView:
private int id;
but Caller(front-end) have to change code.
2. Change fetchType to eager:
UserSupplier:
#ManyToOne
private Supplier supplier;
After reading dozer documentation, I find some thing. After trying it, I got another solution.
That is add a dozer.properties into classpath, content inside is
org.dozer.util.DozerProxyResolver=org.dozer.util.HibernateProxyResolver
More detail please see
http://dozer.sourceforge.net/documentation/proxyhandling.html
This is probably because JPA uses proxy objects for lazy loading of single entity reference. Proxy object is effectively a subclass of your entity class. I guess that dozer can find #Mapping annotation only on fields declared in the class of given object, and not on fields defined in parent classes. Dozer project states that annotation mapping is experimental. Therefore it is possible that it does not cover mapping class hierarchies well.
I suggest to try configure mapping of supplierId by other means (XML, dozer mapping API) and see if it works. If all fails, you could write a custom MapperAware converter between Supplier and SupplierView. You would map source object to target object using supplied mapper, and finilize it by copying value of id to supplierId.
I have two entities. "Price" class has "CalculableValue" stored as SortedMap field.
In order to support sorted map I wrote customizer. After that, it seems #CascadeOnDelete is not working. If I remove CalculableValue instance from map and then save "Price" EclipseLink only updates priceId column to NULL in calculableValues table...
I really want to keep the SortedMap. It helps to avoid lots of routine work for values access on Java level.
Also, there is no back-reference (ManyToOne) defined in the CalculableValue class, it will never be required for application logic, so, wanted to keep it just one way.
Any ideas what is the best way to resolve this issue? I actually have lots of other dependencies like this and pretty much everything is OneToMany relation with values stored in sorted map.
Price.java:
#Entity
#Table(uniqueConstraints={
#UniqueConstraint(columnNames={"symbol", "datestring", "timestring"})
})
#Customizer(CustomDescriptorCustomizer.class)
public class Price extends CommonWithDate
{
...
#CascadeOnDelete
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#MapKeyColumn(name="key")
#JoinColumn(name = "priceId")
private Map<String, CalculatedValue> calculatedValues =
new TreeMap<String, CalculatedValue>();
...
}
public class CustomDescriptorCustomizer implements DescriptorCustomizer
{
#Override
public void customize(ClassDescriptor descriptor) throws Exception
{
DatabaseMapping jpaMapping = descriptor.getMappingByAttribute("calculatedValues");
((ContainerMapping) mapping).useMapClass(TreeMap.class, methodName);
}
}
Your customizer should have no affect on this. It could be because you are using a #JoinColumn instead of using a mappedBy which should normally be used in a #OneToMany.
You can check the mapping in your customizer using, isCascadeOnDeleteSetOnDatabase()
or set it using
mapping.setIsCascadeOnDeleteSetOnDatabase(true)