How to use #XmlIDREF and #XmlID - java

I don't quite understand how #XmlIDREF and #XmlID work together. By using XmlIDREF I only create a reference to the actual element. However what is the use case for XmlID.
I want to create a reference to the class Publication. Is it enough to annotate the publication List with #XmlIDREF?
public class Author {
private String id;
private String name;
private List<Publication> publications = new LinkedList<>();
public Author() {
super();
}
#XmlElement
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#XmlElement
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
#XmlIDREF
public List<Publication> getPublications() {
return publications;
}

I want to create a reference to the class Publication.
Is it enough to annotate the publication List with #XmlIDREF?
No, that's only one half of what you need.
You already have this:
With #XmlIDREF you mark the referencing side of the relation
(pointing from Author to Publication).
public class Author {
...
#XmlIDREF
#XmlElement(name = "publication")
public List<Publication> getPublications() {
return publications;
}
...
}
You also need to mark the referenced side (the Publication itself)
by annotating one of its properties with #XmlID, for example like this:
public class Publication {
...
#XmlID
#XmlElement
public String getId() {
return id;
}
...
}
Then you are able to process XML content like this example:
<root>
<publication>
<id>p-101</id>
<title>Death on the Nile</title>
</publication>
<publication>
<id>p-102</id>
<title>The murder of Roger Ackroyd</title>
</publication>
...
<author>
<id>a-42</id>
<name>Agatha Christie</name>
<publication>p-101</publication>
<publication>p-102</publication>
</author>
...
</root>
You see, the XML references (like <publication>p-101</publication>)
are mapped to Java object references (in List<Publication> publications).

Related

Extending/modifying generated entities in Hibernate

I am creating a REST api service for a mysql database. I've generated classes using IntelliJ's persistence tool. It does a pretty good job.
There are some quirks to the schema that I am working with. The users want the endpoints to be accessible by another property other than the "id" primary key column.
Ex: /object/<name property>' versus/object/`.
Here is the catch though. The schema can change. The name property is not going anywhere though so I can safely assume that will always be on the object.
I've learned that you can use Superclasses to force these generated entites to have custom properties without affecting the database schema. I dont want to make a model change in the generated entity and have that update the database table layout as it is not my database.
I have a class called Animal.
#Entity
#Table(name = "animals", schema = "xyz123", catalog = "")
public class AnimalEntity extends AnimalSuperclass {
private Integer id;
private String name;
private String description;
#Id
#Column(name = "id", nullable = false)
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#Basic
#Column(name = "name", nullable = true, length = 80)
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#Basic
#Column(name = "description", nullable = true, length = 255)
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
RoleEntity that = (RoleEntity) o;
return Objects.equals(id, that.id) &&
Objects.equals(name, that.name) &&
Objects.equals(description, that.description);
}
#Override
public int hashCode() {
return Objects.hash(id, name, description);
}
}
I have to manually add extends AnimalSuperclass. Which is fine for now. Eventually I am going to try to generate these using .xmls on runtime.
Then I have this superclass..
#MappedSuperclass
public class AnimalSuperclass implements Serializable {
private String testMessage;
private String name;
private Integer id;
#Transient
public String getTestMessage() {
return this.testMessage;
}
public void setTestMessage(String id) {
this.testMessage = testMessage;
}
}
What I want to do is force the #Id annotation to be on the name property from within the superclass. Something like this..
#MappedSuperclass
public class AnimalSuperclass implements Serializable {
private String testMessage;
private String name;
private Integer id;
#Transient
public String getTestMessage() {
return this.testMessage;
}
public void setTestMessage(String id) {
this.testMessage = testMessage;
}
#Basic
#Id
#Column(name = "name", nullable = false, length = 15)
private String getName() {
return name;
}
private void setName(String name) {
this.name = name;
}
#NaturalId
#Column(name = "id", nullable = false)
private Integer getId() {
return id;
}
private void setId(Integer id) {
this.id = id;
}
}
How do I go about doing that? Currently this throws an error when I hit the endpoint: {"cause":null,"message":"Id must be assignable to Serializable!: null"}
Java is not my first language so I am not an expert by any means. But from what I've read, its not possible to override subclass properties from the superclass. Is there a better way to approach this, maybe by using RepositoryRestConfiguration? I am using PagingAndSortingRepository to serve these entities. I cannot extend the entities and use my superclass as a child as that creates a dType property in the schema and I cannot alter the table layout.
There is no hard link between the request and your entity. In your repository you can write methods that can query the data that is brought it from the request.
For example if they are requesting a name you can do something like
Page<AnimalEntity> findByName(String name, Pageable pageable);
in your Repository. Spring will take care of the rest and then you can call this in your controller.
#Service
public class AnimalService {
#Autowired
private AnimalEntityRepository animalRepo;
public Page<AnimalEntity> findAnimal(String name) {
Page<AnimalEntity> animals = animalRepo.findByName(name, new PageRequest(1,20));
return animals;
}
}
One thing to mention is that depending on how you configured Hibernate when sending an entity back to the client and the entity is seralized you might get an failed to lazy initialize error. If that is the case your entities will have to be converted to a POJO (plain old java object) and that sent back.

jaxb delete list tag

I need to marshall a java class to get a xml, but i don't know how to delete a tag inside the one generated.
I have a class with an object list with this form
#XmlRootElement(name = "Element")
public class Element {
private List<Foo> foos;
#XmlElementWrapper("fooList")
public List<Foo> getfoos() {
return foos;
}
public void setFoos(List<Foo> foos) {
this.foos = foos;
}
}
And the class Foo of the list is lie this:
#XmlRootElement
public class Foo {
private String id;
private String code;
#XmlElement
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
#XmlElement
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
}
When marshalling to get xml I get this:
<Element>
<fooList>
<foos>
<string1>asd</string1>
<string2>qwe</string2>
</foos>
<foos>
<string1>poi</string1>
<string2>lkj</string2>
</foos>
</fooList>
</Element>
But I want to get it without the tag foos, like this:
<Element>
<fooList>
<string1>asd</string1>
<string2>qwe</string2>
<string1>poi</string1>
<string2>lkj</string2>
</fooList>
</Element>
Can anyone help me?
Thanks a lot!!
You could do something like this:
#XmlRootElement(name = "Element")
#XmlAccessorType(XmlAccessType.FIELD)
public class Element {
#XmlElementWrapper(name = "fooList")
#XmlElements({
#XmlElement(name = "id", type = Id.class),
#XmlElement(name = "code", type = Code.class),
})
private List<FooItem> foos;
public List<FooItem> getfoos() {
return foos;
}
public void setFoos(List<FooItem> foos) {
this.foos = foos;
}
}
and then Id and Code classes look similar:
public class Id implements FooItem {
#XmlValue
private String id;
public Id() {}
public Id(String id) {
this.id = id;
}
}
They are bounded by an interface that doesn't do much:
public interface FooItem { }
This structure will allow you to marshal into xml as the one you specified you need.
The challenge with the class structure you had is that class Foo had 2 fields and #XmlValue can be applied only to one field per class. So having 2 fields "forces" them to stand for #XmlElement and they in turn have to be children of an xml element. This is why you had the "intermediate" foo elements in your xml for each Foo instance in your List.

Spring RestTemplate + map XML result to Domain object

With the use of Spring RestTemplate, how can map following XML result to some Domain Object?
As a solution I have designed following Domain classes but I am wonder whether how can I map those contain values (ex: 100, 200, 300) to domain object property.
Thanks.
XML result
<counting>
<value id="1" name="Robin" date="2015-09-03">100</value>
<value id="2" name="Joy" date="2015-09-03">200</value>
<value id="3" name="Tan" date="2015-09-03">300</value>
<counting>
Domain Class
#XmlRootElement(name = "counting")
public class Count {
private Value value;
public Count() {}
// Getters and setters
}
#XmlRootElement(name = "value")
public class Value {
public Value() {}
private long id;
private String name;
private Date date;
// Getters and setters
}
I have solved the issue with following data model
#XmlRootElement(name = "counting")
public class Count {
private List<Value> value;
public Count() {}
// Getters and setters
#XmlElement
public List<Value> getValue() {
return value;
}
public void setValue(List<Value> value) {
return this.value = value;
}
}
#XmlAccessorType(XmlAccessorType.FIELD)
public class Value {
public Value() {}
#XmlAttribute
private long id;
#XmlAttribute
private String name;
#XmlAttribute
private String date;
#XmlValue
private String xmlValue;
// Getters and setters
}

JAXB EclipseLink Moxy add template xml

i have problem with my jaxb EclipseLink implementation.
Let's assume I have the following Entity ...
#XmlRootElement(name = GenericConfigEntity.XML_ROOT_TAG)
public class GenericConfigEntity {
private String name;
private String data;
private String version;
private String date;
private String template;
#XmlAttribute(name = GenericConfigEntity.XML_NAME)
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#XmlElement(name = GenericConfigEntity.XML_DATA)
public String getData() {
return data;
}
public void setData(String data) {
this.data = data;
}
#XmlAttribute(name = GenericConfigEntity.XML_VERSION)
public String getVersion() {
return version;
}
public void setVersion(String version) {
this.version = version;
}
#XmlAttribute(name = GenericConfigEntity.XML_DATE)
public String getDate() {
return date;
}
public String getTemplate() {
return template;
}
public void setTemplate(String template) {
this.template = template;
}
}
The string 'template' contains xml data already let's say someting like this (in my real context it is a lot more and I do not want to create the entities for this).
<Prozess name="xx" test="1">
<Debug system="test" />
</Prozess>
Now my question is if there is a way to integrate the template string into the marshalling process that someting like this is generated
<conf name="xx" version="x" datum="xx">
<Prozess name="xx" test="1">
<Debug system="test" />
</Prozess>
<Data>
TextTextText
</Data>
</conf>
It is no solution to wrap the template in an tag because i am restricted to this layout.
Also #XmlValue is no solution because I get an exception "all other elements have to be an attribute because one is marked as xmlvalue".
I haven't used this myself yet, but I reckon you could use the #XmlAnyElement in conjunction with a DomHandler to implement such a mapping. You can find a helpful example in the blog of MOXy's lead programmer here.
I think you'd still have to make sure that the XML content in your template field has at least an opening and a closing tag, which serve to identify the DOM element during (un)marshalling. That tag may be arbitrary as required by you. I guess you could just look for the first tag appearing in the string and try to match it against the end of the string.

How do I read attributes using jaxb?

Given this XML:
<response>
<detail Id="123" Length="10" Width="20" Height="30" />
</response>
This is what I have now, but it is not working (I'm getting empty result):
#XmlRootElement(name="response")
public class MyResponse {
List<ResponseDetail> response;
//+getters +setters +constructor
}
public class MyResponseDetail {
Integer Id;
Integer Length;
Integer Width;
Integer Height;
//+getters +setters
}
I'm making a call to a remote service using RestOperations and I want to parse the <detail ..> element. I've tried passing both MyResponse and MyResponseDetail classes to RestOperations but the result is always empty.
What should my object structure look like to match that XML?
You need to annotate your classes like that:
#XmlRootElement
public class Response {
private List<Detail> detail;
public void setDetail(List<Detail> detail) {
this.detail = detail;
}
public List<Detail> getDetail() {
return detail;
}
}
public class Detail {
private String id;
/* add other attributes here */
#XmlAttribute(name = "Id")
public void setId(String id) {
this.id = id;
}
public String getId() {
return id;
}
}

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