We Keep Coding

How to make controller endpoint to get two different objects in java spring?

I have a server built with java and spring.
What i am trying to do is that my controller with the same endpoint will get two different objects.
This is an example for what I mean:
I know I can do that:
public class Option1{
private String name;
...
//getter and setter
}
public class Option2{
private Long id;
...
//getter and setter
}
#Controller
public class Controller{
#RequestMapping(value = "service/getData/option1", method = RequestMethod.POST)
#ResponseBody
public String searchProv(#ResponseBody Option1 data1){
return "option1"
}
#RequestMapping(value = "service/getData/option2", method = RequestMethod.POST)
#ResponseBody
public String searchProv(#ResponseBody Option2 data2){
return "option2"
}
}
but I wonder if it is possible to passing different json object to the same endpoint and do that:
#Controller
public class Controller{
#RequestMapping(value = "service/getData", method = RequestMethod.POST)
#ResponseBody
public ResponseEntity<Any> getData(#ResponseBody Option1And2 data){
if(data instanceof Option1){
return return ResponseEntity<Any>(data.name,HttpStatus.OK)
}
if(data instanceof Option2){
return ResponseEntity<Any>(data.id,HttpStatus.OK)
}
return ResponseEntity<Any>("ok",HttpStatus.OK)
}
such that 'Option1And2' is generic object can be option1 or option2.
I tried to replace 'Option1And2' to 'Any' but it didn't went well because I get a list of keys and values

You should use JsonNode object.
for your example you should do this:
#Controller
public class Controller{
#RequestMapping(value = "service/getData", method = RequestMethod.POST)
#ResponseBody
public ResponseEntity<Any> getData(#RequestBody JsonNode jsonNode){
ObjectMapper obj = new ObjectMapper();
if(jsonNode.has("name"){
Option1 result= obj.convertValue(jsonNode,Option1.class)
return ResponseEntity<Any>(result.name,HttpStatus.OK)
}
else {
Option2 result= obj.convertValue(jsonNode,Option2.class)
return ResponseEntity<Any>(result.id,HttpStatus.OK)
}
return ResponseEntity<Any>("ok",HttpStatus.OK)
}
the JsonNode and the ObjectMapper you should import from here:
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.databind.JsonNode;
this link should help you to understand better on JsonNode and give you more details.
and this link should help you with the convertValue from JsonNode to java object(POJO).

This is a good time to use inheritance and Java Generics. It is worth noting, if your controller has any dependencies such as a #Service or #Repository, then those too must be generic.
You might have a generic controller:
abstract class GenericController<T> {
public abstract GenericService<T> getService();
#GetMapping
public ResponseEntity<Iterable<T>> findAll() {
return ResponseEntity.ok(getService().findAll());
}
#PostMapping
public ResponseEntity<T> save(T entity) {
return ResponseEntity.ok(getService().save(entity));
}
// #DeleteMapping, #PutMapping
// These mappings will automatically be inherited by
// the child class. So in the case of findAll(), the API
// will have a GET mapping on /category as well as a GET
// mapping on /product. So, by defining and annotating the
// CRUD operations in the parent class, they will automatically
// become available in all child classes.
}
#Controller
#RequestMapping("/category")
class CategoryContr extends GenericController<Category> {
#Autowired CategoryServ serv;
#Override
public GenericService<Category> getService() {
return serv;
}
}
#Controller
#RequestMapping("/product")
class ProductContr extends GenericController<Product> {
#Autowired ProductServ serv;
#Override
public GenericService<Product> getService() {
return serv;
}
}
You then have to have abstract versions of the dependencies. The services:
abstract class GenericService<T> {
public abstract GenericRepository<T> getRepository();
public Iterable<T> findAll() {
return getRepository().findAll();
}
public T save(T entity) {
return getRepository().save(entity);
}
}
#Service
class CategoryServ extends GenericService<Category> {
#Autowired CategoryRepo repo;
#Override
public GenericRepository<Category> getRepository() {
return repo;
}
}
#Service
class ProductServ extends GenericService<Product> {
#Autowired ProductRepo repo;
#Override
public GenericRepository<Product> getRepository() {
return repo;
}
}
Then, the services have their dependencies as well - the repositories:
#NoRepositoryBean
interface GenericRepository<T> extends JpaRepository<T, Long> {
}
#Repository
interface CategoryRepo extends GenericRepository<Category> {
}
#Repository
interface ProductRepo extends GenericRepository<Product> {
}
This was my first approach. It works very nicely. However, this does create a strong coupling between the business logic of each service and the generic service. The same holds true for the generic controller and its child classes. You can of course always override a particular CRUD operation. But, you must do this with care as you may created unexpected behavior. It is also worth noting that inheriting from classes that have methods that are annotated with #RequestMapping automatically exposes all of the annotated methods. This may be undesirable. For example, we may not want a delete option for categories, but we want it for products. To combat this, instead of annotating the method in the parent class, we can simply define it in the parent class, and override the desired CRUD operations with the added #RequestMapping annotation and then call the super class method.
Another approach is using annotations.

Seems like you want program itself to determine what type the option is.But before you do that,are you sure what is the difference between these two Object?
First is,what is the Option1And2 actually is?If the Option1And2 contains all the field of Option1 and Option2 but it's not the subclass of those,then probably the Option1And2 could be like:
#Data
public class Option1And2{
private String name;
private Long id;
}
If you have other limits like "one of them and only one of them has
to be null",then you could determine it by this rule.
If you don't have any other limitation,then maybe you could add a new
field as a flag.
In fact those code style are not recommend.If those two functions have different responsibilities,then maybe it's better to not mix them together.You will understand what I mean when you have to refactor these code.
If these two functions do have lots of things in common,maybe it's better for you to refactor the service logic instead of just combining two service roughly by creating a new param Option1And2.
By the way,what are you exactly want to do?Why do you want to merge those two object into one?

How to Inject all subclasses of a specific class with no common interface?

Question:
In order to Inject all subclasses of a superclass with no common interface, I created an interface tightly-coupled to said superclass, that every "properly" written subclass is supposed to implement.
This works, but seems insane. Was there a better way?
A simple cast do not work, as the Instance holds only a proxy that do not resolves to any real subclass of the interface when called. This results in a ClassCastException.
Some context:
I was recently tasked to provide framework code for an application. In this application, several data transfer objects are mapping from and to service level POJOs, but their mappings are not always trivial. Dozer is used to do most of the work and to avoid boilerplate code.
In the specific cases requiring explicit mapping instructions, the current recommendation with Dozer is to use the API driven mapping. All the BeanMappingBuilder subclasses, defining the mappings, should be added to the Dozer mapper upon initialisation.
In order to keep all the work needed to add a new BeanMappingBuilder in one place, I came with a convoluted use of dependancy injection that will automatically add it to the Dozer mapper, despite it having no common interface, only a common superclass with the others.
Some code:
The interface:
#Local
public interface DtoBeanMappingBuilder {
BeanMappingBuilder get();
}
Subclass example:
#Stateless
public class SomeDtoMappingBuilder extends BeanMappingBuilder implements DtoBeanMappingBuilder {
#Override
public BeanMappingBuilder get() {
return this;
}
#Override
protected void configure() {
mapping(
// Some mapping...
);
}
}
Mapper with injection point:
#Singleton
#Startup
public class DtoBeanMapper {
private DozerBeanMapper innerMapper;
#Inject
#Any
private Instance<DtoBeanMappingBuilder> mappingBuilders;
public <D> D map(Object source, Class<D> destinationClass) {
return innerMapper.map(source, destinationClass);
}
#PostConstruct
private void init() {
innerMapper = new DozerBeanMapper();
mappingBuilders.forEach(mb -> innerMapper.addMapping(mb.get()));
}
}

How to make generic jpa repository? Should I do this? Why?

I am new to stack overflow and working on spring jpa data with hibernate and mysql. I have created One JpaRepository for each entity class. But now I feel that I should use One repository for all entities because In all my repositories has common CRUD operation methods.
save()
update()
delete()
findOne()
findAll()
Besides of above methods, I have other custom methods also in my applications.
my aim is to implement GenericRepo like,
public interface MyGenericRepo extends JpaRepository<GenericEntity,Integer>
{
}
my entities will be like:
class Place extends GenericEntity
{
private Event event;
}
class Event extends GenericEntity
{
}
class Offer extends GenericEntity
{
private Place place;
}
class User extends GenericEntity
{
private Place place;
}
when I call:
MyGenericRepo myRepo;
GenericEntity place=new Place();
myRepo.save(place);
It should save place.
[http://openjpa.apache.org/builds/1.0.2/apache-openjpa-1.0.2/docs/manual/jpa_overview_mapping_inher.html#jpa_overview_mapping_inher_joined][1]
I have referred above link and I found that Jpa Inheritance with Joined and Table-Per-Class strategies are similar to what I am looking for, but these all have certain limitations.So please tell me should I try to implement this generic thing.If I get any demo code then I will be very greatful...
Thanks..
How to make generic jpa repository? Should I do this? Why?

If you want to create your own Repos (and not spring data which does some work for you) your example isn't bad, i am using a similar strategy in one application.
Here a few thoughts to improve the generic way:
I've added the ID-information in my basic domain which is implemented by all domain objects:
public interface UniqueIdentifyable<T extends Number> {
T getId();
void setId(T id);
}
In the next step i've created a generic CRUDRepo:
public interface CRUDRepository<ID extends Number, T extends UniqueIdentifyable<ID>>{
ID insert(T entity);
void delete(T entity);
....
}
And I am using an abstract class for the CRUDRepo:
public abstract class AbstractCRUDRepo<ID extends Number, T extends UniqueIdentifyable<ID>> implements CRUDRepo<ID, T>, {...}
a domain repo api will now look like:
public interface UserRepo extends CRUDRepo<Integer, User > {
User mySpecificQuery(..);
}
and finally you can implement your repo via:
public class UserRepoImpl extends AbstractCRUDRepo<Integer, User > implements UserRepo {
public User mySpecificQuery(..){..}
}

Using generics in Spring Data JPA repositories

I have a number of simple object types that need to be persisted to a database. I am using Spring JPA to manage this persistence. For each object type I need to build the following:
import org.springframework.data.jpa.repository.JpaRepository;
public interface FacilityRepository extends JpaRepository<Facility, Long> {
}
public interface FacilityService {
public Facility create(Facility facility);
}
#Service
public class FacilityServiceImpl implements FacilityService {
#Resource
private FacilityRepository countryRepository;
#Transactional
public Facility create(Facility facility) {
Facility created = facility;
return facilityRepository.save(created);
}
}
It occurred to me that it may be possible to replace the multiple classes for each object type with three generics based classes, thus saving a lot of boilerplate coding. I am not exactly sure how to go about it and in fact if it is a good idea?

First of all, I know we're raising the bar here quite a bit but this is already tremendously less code than you had to write without the help of Spring Data JPA.
Second, I think you don't need the service class in the first place, if all you do is forward a call to the repository. We recommend using services in front of the repositories if you have business logic that needs orchestration of different repositories within a transaction or has other business logic to encapsulate.
Generally speaking, you can of course do something like this:
interface ProductRepository<T extends Product> extends CrudRepository<T, Long> {
#Query("select p from #{#entityName} p where ?1 member of p.categories")
Iterable<T> findByCategory(String category);
Iterable<T> findByName(String name);
}
This will allow you to use the repository on the client side like this:
class MyClient {
#Autowired
public MyClient(ProductRepository<Car> carRepository,
ProductRepository<Wine> wineRepository) { … }
}
and it will work as expected. However there are a few things to notice:
This only works if the domain classes use single table inheritance. The only information about the domain class we can get at bootstrap time is that it will be Product objects. So for methods like findAll() and even findByName(…) the relevant queries will start with select p from Product p where…. This is due to the fact that the reflection lookup will never ever be able to produce Wine or Car unless you create a dedicated repository interface for it to capture the concrete type information.
Generally speaking, we recommend creating repository interfaces per aggregate root. This means you don't have a repo for every domain class per se. Even more important, a 1:1 abstraction of a service over a repository is completely missing the point as well. If you build services, you don't build one for every repository (a monkey could do that, and we're no monkeys, are we? ;). A service is exposing a higher level API, is much more use-case drive and usually orchestrates calls to multiple repositories.
Also, if you build services on top of repositories, you usually want to enforce the clients to use the service instead of the repository (a classical example here is that a service for user management also triggers password generation and encryption, so that by no means it would be a good idea to let developers use the repository directly as they'd effectively work around the encryption). So you usually want to be selective about who can persist which domain objects to not create dependencies all over the place.
Summary
Yes, you can build generic repositories and use them with multiple domain types but there are quite strict technical limitations. Still, from an architectural point of view, the scenario you describe above shouldn't even pop up as this means you're facing a design smell anyway.

This is very possible! I am probably very late to the party. But this will certainly help someone in the future. Here is a complete solution that works like a charm!
Create BaseEntity class for your entities as follows:
#MappedSuperclass
public class AbstractBaseEntity implements Serializable{
#Id #GeneratedValue
private Long id;
#Version
private int version;
private LocalDateTime createdAt;
private LocalDateTime updatedAt;
public AbstractBaseEntity() {
this.createdAt = LocalDateTime.now();
this.updatedAt = LocalDateTime.now();
}
// getters and setters
}
Create a generic JPA Repository interface for your DAO persistence as follows:
NB. Remember to put the #NoRepositoryBean so that JPA will not try to find an implementation for the repository!
#NoRepositoryBean
public interface AbstractBaseRepository<T extends AbstractBaseEntity, ID extends Serializable>
extends JpaRepository<T, ID>{
}
Create a Base Service class that uses the above base JPA repository. This is the one that other service interfaces in your domain will simply extend as follows:
public interface AbstractBaseService<T extends AbstractBaseEntity, ID extends Serializable>{
public abstract T save(T entity);
public abstract List<T> findAll(); // you might want a generic Collection if u prefer
public abstract Optional<T> findById(ID entityId);
public abstract T update(T entity);
public abstract T updateById(T entity, ID entityId);
public abstract void delete(T entity);
public abstract void deleteById(ID entityId);
// other methods u might need to be generic
}
Then create an abstract implementation for the base JPA repository & the basic CRUD methods will also be provided their implementations as in the following:
#Service
#Transactional
public abstract class AbstractBaseRepositoryImpl<T extends AbstractBaseEntity, ID extends Serializable>
implements AbstractBaseService<T, ID>{
private AbstractBaseRepository<T, ID> abstractBaseRepository;
#Autowired
public AbstractBaseRepositoryImpl(AbstractBaseRepository<T, ID> abstractBaseRepository) {
this.abstractBaseRepository = abstractBaseRepository;
}
#Override
public T save(T entity) {
return (T) abstractBaseRepository.save(entity);
}
#Override
public List<T> findAll() {
return abstractBaseRepository.findAll();
}
#Override
public Optional<T> findById(ID entityId) {
return abstractBaseRepository.findById(entityId);
}
#Override
public T update(T entity) {
return (T) abstractBaseRepository.save(entity);
}
#Override
public T updateById(T entity, ID entityId) {
Optional<T> optional = abstractBaseRepository.findById(entityId);
if(optional.isPresent()){
return (T) abstractBaseRepository.save(entity);
}else{
return null;
}
}
#Override
public void delete(T entity) {
abstractBaseRepository.delete(entity);
}
#Override
public void deleteById(ID entityId) {
abstractBaseRepository.deleteById(entityId);
}
}
How to use the above abstract entity, service, repository, and implementation:
Example here will be a MyDomain entity. Create a domain entity that extends the AbstractBaseEntity as follows:
NB. ID, createdAt, updatedAt, version, etc will be automatically be included in the MyDomain entity from the AbstractBaseEntity
#Entity
public class MyDomain extends AbstractBaseEntity{
private String attribute1;
private String attribute2;
// getters and setters
}
Then create a repository for the MyDomain entity that extends the AbstractBaseRepository as follows:
#Repository
public interface MyDomainRepository extends AbstractBaseRepository<MyDomain, Long>{
}
Also, Create a service interface for the MyDomain entity as follows:
public interface MyDomainService extends AbstractBaseService<MyDomain, Long>{
}
Then provide an implementation for the MyDomain entity that extends the AbstractBaseRepositoryImpl implementation as follows:
#Service
#Transactional
public class MyDomainServiceImpl extends AbstractBaseRepositoryImpl<MyDomain, Long>
implements MyDomainService{
private MyDomainRepository myDomainRepository;
public MyDomainServiceImpl(MyDomainRepository myDomainRepository) {
super(myDomainRepository);
}
// other specialized methods from the MyDomainService interface
}
Now use your `MyDomainService` service in your controller as follows:
#RestController // or #Controller
#CrossOrigin
#RequestMapping(value = "/")
public class MyDomainController {
private final MyDomainService myDomainService;
#Autowired
public MyDomainController(MyDomainService myDomainService) {
this.myDomainService = myDomainService;
}
#GetMapping
public List<MyDomain> getMyDomains(){
return myDomainService.findAll();
}
// other controller methods
}
NB. Make sure that the AbstractBaseRepository is annotated with #NoRepositoryBean so that JPA does not try to find an implementation for the bean.
Also the AbstractBaseServiceImpl must be marked abstract, otherwise JPA will try to autowire all the children daos of the AbstractBaseRepository in the constructor of the class leading to a NoUniqueBeanDefinitionException since more than 1 daos (repository) will be injected when the bean is created!
Now your service, repository, and implementations are more reusable. We all hate boilerplate!
Hope this helps someone.

I am working a project to create the generic repository for cassandra with spring data.
Firstly create a repository interface with code.
StringBuilder sourceCode = new StringBuilder();
sourceCode.append("import org.springframework.boot.autoconfigure.security.SecurityProperties.User;\n");
sourceCode.append("import org.springframework.data.cassandra.repository.AllowFiltering;\n");
sourceCode.append("import org.springframework.data.cassandra.repository.Query;\n");
sourceCode.append("import org.springframework.data.repository.CrudRepository;\n");
sourceCode.append("\n");
sourceCode.append("public interface TestRepository extends CrudRepository<Entity, Long> {\n");
sourceCode.append("}");
Compile the code and get the class, I use org.mdkt.compiler.InMemoryJavaCompiler
ClassLoader classLoader = org.springframework.util.ClassUtils.getDefaultClassLoader();
compiler = InMemoryJavaCompiler.newInstance();
compiler.useParentClassLoader(classLoader);
Class<?> testRepository = compiler.compile("TestRepository", sourceCode.toString());
And initialize the repository in spring data runtime. This is a little tricky as I debug the SpringData code to find how it initialize a repository interface in spring.
CassandraSessionFactoryBean bean = context.getBean(CassandraSessionFactoryBean.class);
RepositoryFragments repositoryFragmentsToUse = (RepositoryFragments) Optional.empty().orElseGet(RepositoryFragments::empty);
CassandraRepositoryFactory factory = new CassandraRepositoryFactory(
new CassandraAdminTemplate(bean.getObject(), bean.getConverter()));
factory.setBeanClassLoader(compiler.getClassloader());
Object repository = factory.getRepository(testRepository, repositoryFragmentsToUse);
Now you can try the save method of the repository and you can try other methods such as findById.
Method method = repository.getClass().getMethod("save", paramTypes);
T obj = (T) method.invoke(repository, params.toArray());
A full sample code and implementation I have put in this repo
https://github.com/maye-msft/generic-repository-springdata.
You can extend it to JPA with the similar logic.

How to inject a service within abstract class using generics

I am attempting to create a generic abstract service class that provides common crud operations to my service layer by bringing together Service layer Objects (DTO?), Data layer Entities and their corresponding DAOs.
The DAO layer is standard-issue abstraction where my DAOs extend an AbstractJpaImpl:
#Repository
public abstract class AbstractJpaBaseDaoImpl<K extends Serializable, E> implements BaseDao<K, E> {
//Dao implementation
}
The DAOs extend this class and implement their respective dao interface that extends BaseDao.
I wish to create something similar in my service layer, but how would i inject the dao itself?
public abstract class AbstractBaseCrudServiceImpl<K extends Serializable, B extends AbstractBaseCrudBean, P, D extends AbstractJpaBaseDaoImpl<K,P>>
implements BaseCrudService<K, B> {
protected Class<B> businessObject;
protected Class<P> persistObject;
protected Class<D> dao;
#SuppressWarnings("unchecked")
public AbstractBaseCrudServiceImpl() {
//Extract the class type by accessing this classes parameters by index <0,1...> so 0 is K and 1 is E.
this.businessObject = (Class<B>) ((ParameterizedType) this.getClass().getGenericSuperclass()).getActualTypeArguments()[1];
this.persistObject = (Class<P>) ((ParameterizedType) this.getClass().getGenericSuperclass()).getActualTypeArguments()[2];
this.dao = (Class<D>) ((ParameterizedType) this.getClass().getGenericSuperclass()).getActualTypeArguments()[3];
}
//stuff ...
#Transactional
#SuppressWarnings("unchecked")
#Override
public void remove(B businessObject) {
logger.debug("Remove " + getBusinessObjectCanonicalName() + " id= " + businessObject.getId());
try {
getDao().remove(businessObject.getId()); //DOES NOT RECOGNIZE REMOVE METHOD
} catch (Exception e) {
logger.error("Unable to delete " + getBusinessObjectCanonicalName() + " record id=" + businessObject.getId(), e);
}
}
//stuff ...
}
Whats the cleanest way to inject a service within this abstract using generics?
D extends AbstractJpaBaseDaoImpl aint cutting it. Is there a pattern i can follow?

You may try using the #PostConstruct annotated method to wire the variable in the base abstract classes with real instantiated beans. These abstract classes can contacin basic CRUd operation implementations. Example code provided below. I hope I helped your query in some way.
#PostConstruct public void setupService() {
baseDao = userDao;
}

What are the definitions of some of the other types? Such as AbstractBaseCrudBean, BaseCrudService, etc.? There are so many compilation errors it is hard to get down to what your root issue is.
However, the reason the simple generic declaration is not cutting it is that there is no instance on which to invoke the methods of D. You would need something like:
private final D dao;
And then decorate that with #Inject #Named (since after erasure you will likely have many DAO's of the same type). So, each implementation of a DAO will need to have a unique string name, which may or not be a big deal.