I have a Mcq class associated to a MongoRepository, and I want to get an instance of my Mcq which apply several changes (Answers shuffle, Questions draw, etc). I declared my function "myMcq.getInstance()", but I can't do that because every time I want to send a Mcq in a ResponseEntity there is an error in the JSON output because Springboot thinks that there is a "instance" property in my class.
Here is my java class :
#Document(collection = "Mcqs")
public class Mcq {
#Id public String id;
#DBRef public User creator;
public String title;
public String categoryID;
public List<McqChapter> chapterList = new ArrayList<>();
public Difficulty difficulty;
public Mcq() {}
public Mcq(String title) {
this();
this.title = title;
}
public ArrayList<String> getQuestionsIDs() {
ArrayList<String> result = new ArrayList<>();
for (McqChapter chapter : chapterList) result.addAll(chapter.getQuestionIDs());
return result;
}
public McqInstance getInstance() {
return new McqInstance(this);
}
}
To prevent the error add #JsonIgnore to getInstance() method:
#JsonIgnore
public McqInstance getInstance() {
return new McqInstance(this);
}
Marker annotation that indicates that the annotated method or field is to be ignored by introspection-based serialization and deserialization functionality. That is, it should not be consider a "getter", "setter" or "creator".
Related
I have a class Data with list and two variable (id and name). I am replacing the variable with list values. First time in the list will be the new values of the id and name. After removing the id and name, the request object will contain only dataList. But the issue is the variable is being used in many places. I am thinking of creating the setter of the id and name properties in the Request object.
I created the getter and but not sure how to create the setter such that I add items to list for the same object. Also, how to override builder for those two fields alone. Assume the request object is big as well.
Class Request
#Builder
#Getter
public class Request {
private String id; //need to removed
private String name; //need to removed
private List<Data> dataList;
public String getId() {
return (dataList != null) ? dataList.get(0).getId() : null;
}
public String getName() {
return (dataList != null) ? dataList.get(0).getName() : null;
}
}
Class Data:
public class Data {
private String id;
private String name;
}
When someone calls setId or setName, then the item at index 0 in the dataList should be updated.
How do I do the same for builder ?
Overriding Lombok's setter doesn't change the builder's behavior, you have to override them both. Let's start with the harder one:
Builder
Lombok's builder is easy to be overridden by defining the skeleton of the builder. The existing parts won't be generated and Lombok only completes the builder. Create athisstatic nested class in Request:
public static class RequestBuilder {
public final RequestBuilder id(final String id) {
this.id = id;
updateData(id, name, dataList);
return this;
}
public final RequestBuilder name(final String name) {
this.name = name;
updateData(id, name, dataList);
return this;
}
}
What is updateData? You need to update the dataList on each builder's method call. The method must be static otherwise the static builder cannot access it. Define it right in the Request class:
private static void updateData(final String id, final String name, List<Data> dataList) {
if (dataList == null) {
dataList = new ArrayList<>();
}
if (dataList.isEmpty()) {
dataList.add(new Data(id, name));
} else {
var data = dataList.get(0);
data.setId(id);
data.setName(name);
}
}
Your case when dataList is null is not handled, so I rather initialize it here for sure (hence the field cannot be final among the formal parameters of the method).
Setter
This is easy, you need to do basically the same thing like in the builder - just override the correct methods:
public final void setId(final String id) {
this.id = id;
updateData(id, getName(), dataList);
}
public final void setName(final String name) {
this.name = name;
updateData(getId(), name, dataList);
}
You are all set. For sake of simplicity, I have annotated the class Data with Lombok annotations #lombok.Data (beware of the name) and #AllArgsConstructor.
Test
It's always a good practice to write at least some units tests to cover and verify the behavior. I needed to annotate Request with #AllArgsConstructor to avoid calling the setters which are subjects of the test. I also would need some helpful methods for assertion and eliminating code duplication:
void assertRequestBeforeTest(final Request request) {
assertThat(request.getId(), nullValue());
assertThat(request.getName(), nullValue());
assertThat(request.getDataList(), hasSize(0));
}
void assertRequestAfterTest(final Request request, final String id, final String name) {
assertThat(request.getId(), is(id));
assertThat(request.getName(), is(name));
assertThat(request.getDataList(), notNullValue());
var data = request.getDataList().get(0);
assertThat(data, notNullValue());
assertThat(data.getId(), is(id));
assertThat(data.getName(), is(name));
}
And the tests:
#Test
void setter_onNullFields() {
var request = new Request(null, null, new ArrayList<>());
assertRequestBeforeTest(request);
request.setId("id-new");
request.setName("name-new");
assertRequestAfterTest(request, "id-new", "name-new");
}
#Test
void setter_onExistingFields() {
var request = new Request("id", "name", new ArrayList<>());
assertRequestBeforeTest(request);
request.setId("id-new");
request.setName("name-new");
assertRequestAfterTest(request, "id-new", "name-new");
}
#Test
void builder() {
var requestBuilder = Request.builder().dataList(new ArrayList<>());
var request = requestBuilder.id("id-new").name("name-new").build();
assertRequestAfterTest(request, "id-new", "name-new");
}
You only need to override the set method and set values within the method
public void setId(String id) {
if (dataList == null) {
dataList = new ArrayList(2);
}
if (null == dataList.get(0)) {
dataList.add(0, new Data());
}
dataList.get(0).setId(id);
}
If many places are calling the Request object. You can replace the setter of the id and name properties in the Request object. When rewriting the setter method of the id and name properties in the Request object, you can call the setter method of the Data object to write
I have a Entity class something like this:
#Entity
public class Website {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
private String name;
private String url;
public Website() {
//Constructor
//getters and setters
}
here is the DTO class:
public class WebsiteDto {
private Integer id;
private String name;
private String url;
public WebsiteVo() {
//Constructor
//getters and setters
}
I have the WebsiteMapper something like this:
#Component
public class WebsiteMapper {
public List<WebsiteDto> getWebsiteList() {
return repository.findAll().stream().map(w -> {
WebsiteDto dto = new WebsiteVo(w.getId(), w.getName(), w.getUrl());
return dto;
}).collect(Collectors.toList());
I also have Repository Interface:
public interface WebsiteRepository extends JpaRepository<Website, Integer> {
}
I want now to convert DTO to entity using my class WebsiteMapper. Because I did the conversion in this class. How I can do it?
How about using BeanUtils provided by spring org.springframework.beans.BeanUtils, something like this
public List<WebsiteDto> getWebsiteList() {
return repository.findAll().stream().map(w -> {
WebsiteDto dto = new WebsiteVo();
BeanUtils.copyProperties(w, dto); // copys all variables with same name and type
return dto;
})
.collect(Collectors.toList());
}
Hi I guess you wish to converting your entity to DTO. It's quite simple. Create static methods in your DTO class or any util class. The return type should be your DTO type.
e.g.
public class WebsiteDto {
private Integer id;
private String name;
private String url;
public static WebsiteDto export(Website website) {
// Return a new instance of your website DTO
return new WebsiteDto(
website.getId(),
website.getName(),
website.getUrl()
);
}
public static List<WebsiteDto> export(List<Website> websites) {
// Return a new instance of your website DTO list
return websites.stream().map(website -> {
return new WebsiteDto(
website.getName(),
website.getUrl()
}).collect(Collectors.toList());
}
}
NOTE You can also convert your DTO to entity using similar method.
public class LocationBasedRole extends AbstractEntity{
#ManyToMany(fetch=FetchType.LAZY)
private Set<Role> roles=new HashSet<Role>();
#ManyToMany(fetch=FetchType.LAZY)
private Set<Location> locations=new HashSet<Location>();
}
public class Role extends AbstractEntity{
private String name;
}
public class Location extends AbstractEntity{
private String location;
}
I have an entity named locationBasedRole which has 2 properties named roles and locations. Both roles and locations have a #ManyToMany relation with locationBasedRole.
Now I want to have one property of each in a Vaadin Table. It should be something like this,
public class UserForm extends OgsAbstractForm<User>{
MTable<LocationBasedRole> locationBasedRoleTable = new MTable<LocationBasedRole>().withHeight("100%").withWidth("100%");
#Override
protected Component createContent() {
Set<LocationBasedRole> lbRoles=new HashSet<LocationBasedRole>();
roles.addAll(locationBasedRoleFasade.findAll());
BeanItemContainer<LocationBasedRole> bean=new BeanItemContainer<LocationBasedRole>(LocationBasedRole.class);
//It returns an error on the next both lines and I know the reason, but don't know how to solve it.
// If it was no ManyToMany relation and the properties weren't a collection, it would work
bean.addNestedContainerProperty("roles.name");
bean.addNestedContainerProperty("locations.location");
bean.removeContainerProperty("persistent");
bean.removeContainerProperty("id");
bean.addAll(lbRoles);
locationBasedRoleTable.setContainerDataSource(bean);
return new VerticalLayout(locationBasedRoleTable);
}
}
When I remove the properties from the NestedContainerProperties it shows me at least something in the table.
bean.addNestedContainerProperty("roles");
bean.addNestedContainerProperty("locations");
I could use any help!
Thanks in advance!
So if I understand your question right, you want to have the Collections of your BeanItemContainer-Entity displayed in one column each?
I see two possibilities for that.
Option 1 - use a wrapper class for your Sets and use addNestedContainerBean
One possibility would be to not use Sets inside your LocationBasedRole but to use a wrapper class that extends HashSet.
Then you could use the addNestedContainerBean method.
I created a small example with the BeanItemContainer-Entity Team
public class Team {
private String teamName;
private Members teamMembers;
public String getTeamName() {
return teamName;
}
public void setTeamName(String teamName) {
this.teamName = teamName;
}
public Members getTeamMembers() {
return teamMembers;
}
public void setTeamMembers(Members teamMembers) {
this.teamMembers = teamMembers;
}
}
Which consists of a name and teamMembers. The latter is of type Members:
public class Members extends HashSet<TeamMember> {
public String getMembers() {
return this.stream()
.map(member -> member.getFirstName() + " " + member.getLastName())
.collect(Collectors.joining(","));
}
}
Which is a simple wrapper for the Set that contains instances of TeamMember:
public class TeamMember {
private String firstName;
private String lastName;
private Integer age;
// getters and setters
}
As you can see in the Members class, there is a method getMembers which returns a String, containing a comma separated list of the team members names.
If we now use addNestedContainerBean("teamMembers") Vaadin tries to display all properties contained in the class Members. Vaadin will think getMembers is a getter for a String property called members and so generate a column for it.
Vaadin will also display a column "empty" because it will find the isEmpty method of Set and think empty is a property to display in a column. So we tell Vaadin to remove that column.
The final code of my example looks like:
protected Component createContent() {
Set<Team> teams=new HashSet<>();
for (int teamCounter = 0; teamCounter < 5; teamCounter++) {
Team team = createTeam();
addMembersToTeam(5, team);
teams.add(team);
}
BeanItemContainer<Team> bean=new BeanItemContainer<>(Team.class);
bean.addNestedContainerBean("teamMembers");
bean.removeContainerProperty("teamMembers.empty");
bean.addAll(teams);
teamTable.setContainerDataSource(bean);
return new VerticalLayout(teamTable);
}
The result looks like:
Option 2 - create fake getters and use addNestedContainerProperty
The only thing you have to do for this is extend your BeanItemContainer-Entity (LocationBasedRole) and create a fake getter for each Set you want to be displayed in a column. In your example those two fake getters could be public String getTheRoles() and public String getTheLocations(). Then you can use bean.addNestedContainerProperty("theRoles") and bean.addNestedContainerProperty("theLocations").
In my example my TeamMember class (the counterpart to your Role / Location classes) would still look like in the option above:
public class TeamMember {
private String firstName;
private String lastName;
private Integer age;
// getters and setters
}
And my Team class (your LocationBasedRole) would look like:
public class Team {
private String teamName;
private Set<TeamMember> teamMembers;
public String getTeamName() {
return teamName;
}
public void setTeamName(String teamName) {
this.teamName = teamName;
}
public Set<TeamMember> getTeamMembers() {
return teamMembers;
}
public void setTeamMembers(Set<TeamMember> teamMembers) {
this.teamMembers = teamMembers;
}
public String getMembers() {
if (teamMembers != null) {
return teamMembers.stream()
.map(member -> member.getFirstName() + " " + member.getLastName())
.collect(Collectors.joining(","));
} else {
return "No members";
}
}
}
Now you can tell vaadin to add the (not existing) property "members" and Vaadin will find the getter getMembers and use this for generating the column. We also have to tell vaadin not to display the original "teamMembers" property. So the final code is:
protected Component createContent() {
Set<Team> teams=new HashSet<>();
for (int teamCounter = 0; teamCounter < 5; teamCounter++) {
Team team = createTeam();
addMembersToTeam(5, team);
teams.add(team);
}
BeanItemContainer<Team> bean=new BeanItemContainer<>(Team.class);
bean.addNestedContainerProperty("members");
bean.removeContainerProperty("teamMembers");
bean.addAll(teams);
teamTable.setContainerDataSource(bean);
return new VerticalLayout(teamTable);
}
and the result looks like:
I'm trying to deserialize JSON Array, which is persisted into my MongoDB, to a Java object by using Jackson. I found many tutorials mentioned to handle this polymorphism by adding:
#JsonTypeInfo(use=Id.CLASS,property="_class")
to a Super-class. However, in my case, I can't be able to modify the Super-class. So, are there some solutions to solve it without modifying the Super-class? Here is my code:
public class User {
#JsonProperty("_id")
private String id;
private List<Identity> identities; // <-- My List contains objects of an abstract class; Identity
public User(){
identities = new ArrayList<Identity>();
}
public static Iterable<User> findAllUsers(){
return users().find().as(User.class); // Always give me the errors
}
/*More code*/
}
It always give me the error - Can not construct instance of securesocial.core.Identity, problem: abstract types either need to be mapped to concrete types, have custom deserializer, or be instantiated with additional type information.
You can use #JsonDeserilize annotation to bind a concrete implementation class to an abstract class. If you cannot modify your abstract class you can use the Jackson Mix-in annotations to tell Jackson how to find the implementation class.
Here is an example:
public class JacksonAbstract {
public static class User {
private final String id;
private final List<Identity> identities;
#JsonCreator
public User(#JsonProperty("_id") String id, #JsonProperty("identities") List<Identity> identities) {
this.id = id;
this.identities = identities;
}
#JsonProperty("_id")
public String getId() {
return id;
}
public List<Identity> getIdentities() {
return identities;
}
}
public static abstract class Identity {
public abstract String getField();
}
#JsonDeserialize(as = IdentityImpl.class)
public static abstract class IdentityMixIn {
}
public static class IdentityImpl extends Identity {
private final String field;
public IdentityImpl(#JsonProperty("field") String field) {
this.field = field;
}
#Override
public String getField() {
return field;
}
}
public static void main(String[] args) throws IOException {
User u = new User("myId", Collections.<Identity>singletonList(new IdentityImpl("myField")));
ObjectMapper mapper = new ObjectMapper();
mapper.addMixInAnnotations(Identity.class, IdentityMixIn.class);
String json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(u);
System.out.println(json);
System.out.println(mapper.readValue(json, User.class));
}
}
In AppEngine I need to have an entity Diagram that contains an id, title and a variable list of elements of inner class Box, each one with id and description.
Please find below the definition. However, at time of defining the EntityProxy List getter and setter: "The type java.util.List<Box> cannot be used here".
DIAGRAM.java
#Entity
public class Diagram extends DatastoreObject {
public class Box {
private String boxId;
private String description;
public String get_id() {
return boxId;
}
public void set_id(String boxId) {
this.boxId = boxId;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
#Indexed private String diagramId; // Primary key
#Indexed private String title;
#Embedded private List<Box> boxes;
public String get_id() {
return diagramId;
}
public void set_id(String diagramId) {
this.diagramId = diagramId;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public void setBoxes(List<Box> boxes) {
this.boxes = boxes
}
public List<Box> getBoxes() {
return boxes;
}
}
DIAGRAMPROXY.java
[...]
List<Box> getBoxes();
void setBoxes(List<Box> boxes);
[...]
Your inner class must be static. Nonstatic inner classes have an implicit link to an instance of the outer class, which would be really confusing from the perspective of loading and saving entities to the datastore.
Confusing, you have a Collection<Box> in the Box class? Doesnt sound right.. Anyways the inner Box class must be market static or be moved to a different file. Use the #Embed (version 4.0) annotation on the Box class.
Also, assuming DatastoreObject is the base of all your entities, you can make DatastoreObject as an #Entity and all its sub classes as an #EntitySubClass (index = true). Obviously all sub entities would be be saved under the same 'kind' (DatastoreObject) in the datastore.