I have multiple objects in my array using . If I then send this to my Spring Boot backend with axios and output the FormData beforehand, I get the following image. That fits. In the backend, however, I need this list of objects as an entity. In this case, of type List. Do I do that?
Frontend code:
let data = new FormData();
...
data.append("zugeordnet", JSON.stringify(personNamen));
await axios.post("/neuerEintrag", data,...)
React:
Backend:
#PostMapping("/neuerEintrag")
public String neuerEintrag(HttpServletRequest req,#RequestParam("zugeordnet") List<?> zugeordnet,..) {
List<User> userListe = (List<User>) zugeordnet;
for(User inListe : userListe) //ERROR here
{
System.out.println("USER :" + inListe);
}
...
}
java.lang.ClassCastException: class java.lang.String cannot be cast to class com.home.calendar.User.User
UPDATE
For completeness, here is the user entity and the complete method for a new entry.
#PostMapping("/neuerEintrag")
public String neuerEintrag(HttpServletRequest req, #RequestParam("beschreibung") String beschreibung,
#RequestParam("datum") Date datum, #RequestBody List<User> zugeordnet,
#RequestBody List<Freunde> kontaktAuswahl, #RequestParam("neuAlt") String neuAlt,
#RequestParam("kalenderId") int kalenderId) { }
The User Entity:
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
private String name;
#JsonIgnoreProperties("user")
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true, mappedBy = "user")
private List<Kalender> kalenderEinträge;
public User() {
super();
// TODO Auto-generated constructor stub
}
public User(String name, List<Kalender> kalenderEinträge) {
super();
this.name = name;
this.kalenderEinträge = kalenderEinträge;
}
public List<Kalender> getKalenderEinträge() {
return kalenderEinträge;
}
[getter/setter]
Spring can't parse an unknown object.
To get it work, I suggest a new class for the "request".
#Data // lombok - this generates getter/setters/equals/hashcode for you
public class NeuerEintragRequest {
private List<User> zugeordnet;
private String beschreibung;
private int kalendarId;
// and your others fields
}
The controller can now use very type-safe objects.
#PostMapping("/neuerEintrag")
public String neuerEintrag(#RequestBody NeuerEintragRequest request) {
for(User user : request.getUserlist()) {
// a logging framework is a lot better. Try to use log4j or slf4j.
log.info("USER: {}", user);
}
...
}
Typescript
Let axios handle the typing and serializing. See this tutorial: https://masteringjs.io/tutorials/axios/post-json
To post all the needed data, you can create a new object.
// no formdata - just send the object
const data = { zugeordnet: personNamen, kalendarId: 123, beschreibung: 'abc' };
await axios.post("/neuerEintrag", data);
You can also create a interface in typescript, but this is going to much for a stackoverflow-answer. Try to learn more about spring and typescript.
Based on question & comments ,
your front end call data.append("zugeordnet", JSON.stringify(personNamen)); is converting your object to List<String> instead of List<User>.
So you can transform this List<String> to List<User> in your postMapping:
#PostMapping("/neuerEintrag")
public String neuerEintrag(HttpServletRequest req,#RequestParam("zugeordnet") List<?> zugeordnet,..) {
ObjectMapper mapper=new ObjectMapper();
for(String str:zugeordnet){
System.out.println(mapper.readValue(str, User.class));
}
...
}
How can I check the DB if a record already exists for a given case using Spring JPA query using one params. If it exists it does an update or else it inserts as a new record. I have tried a simple implementation, but I end up with a 500 server error no other error is logged.
Resolved [java.lang.NullPointerException] Completed 500
INTERNAL_SERVER_ERROR
This is what I have tried so far
My Controller
#RequestMapping(path="/updatedm",method = RequestMethod.POST)
public Boolean updateDMStatus(#RequestParam("country") String country,
#RequestParam("Id") String pId,
#RequestParam("case") String case,
#RequestParam("status") String status,
#RequestParam("updatedBy") String updatedBy){
Boolean createDm = eaDataStoreService.updateDM(country,Id,case,status,updatedBy);
return createDm;
}
My repository
public interface DMValidatedRepository extends CrudRepository<DMValidated, String> {
DMValidated findByCase(#Param("case") String case);
}
My Service
public boolean updateDM(String country, String Id, String case, String status,String updatedBy) {
DMValidated document = dmValidated.findByCase(case);
if(document != null){
document.setStatus(status);
document.setUpdatedBy(updatedBy);
dmValidated.save(document);
}else{
document.getId();
document.getCase();
document.getCountry();
document.getStatus();
document.getUpdatedBy();
dmValidated.save(document);
}
return true;
}
My Model
#Data
#ToString
#Entity
#Table(name = "DMStatus")
public class DMValidated{
#Id
#GeneratedValue
private String id;
#Column(name = "country")
private String country;
#Column(name = "Id")
private String Id;
#Column(name = "Case")
private String case;
#Column(name = "status")
private String status;
#Column(name = "updatedBy")
private String updatedBy;
public DMValidated( String country, String Id,
String case, String status, String updatedBy){
this.country = country;
this.Id=Id;
this.case = case;
this.status =status;
this.updatedBy = updatedBy;
}
Am not sure if this is the right way of doing this, have tried to research but I have not found something concreate. How can I achieve this?
It's not difficult you have just forgotten the code to create properly the object when it is new and needs to be inserted
if(document != null){
document.setStatus(status);
document.setUpdatedBy(updatedBy);
}else{
document = new DMValidated();
document.setId(Id);
document.setCase(case);
document.setCountry(country);
document.setStatus(status);
document.setUpdatedBy(updatedBy);
}
dmValidated.save(document);
The error that occurred previously in your code is the following
}else{
document.getId();
...
}
In this else you get only when document == null, so when you invoke document.getId() a null pointer exception is thrown, and then 500 error occurs.
else{
document.getId();
document.getCase();
document.getCountry();
document.getStatus();
document.getUpdatedBy();
dmValidated.save(document);
}
above case document object initialize but property datatype string is always null
Thats why each time document.getId() is null or other property to get occurred Nullpointer.
Correct code
else{
document = new DMValidated();
document.setId(Id);
document.setCase(case);
document.setCountry(country);
document.setStatus(status);
document.setUpdatedBy(updatedBy);
}
This operation you are attempting to do is colloquially called UPSERT, and happens to be a bit of challenge to achieve purely with JPA and Hibernate. The way I've done it in the past is with jOOQ.
That said, there are good resources here in StackOverflow that will help you find an answer faster if you search for those keywords.
Anyhow, here are some readings you may want to go over first:
https://www.jooq.org/doc/3.1/manual/sql-building/sql-statements/insert-statement/insert-on-duplicate-key/
https://www.depesz.com/2012/06/10/why-is-upsert-so-complicated/
https://vladmihalcea.com/jooq-facts-from-jpa-annotations-to-jooq-table-mappings/
UPSERT in PostgreSQL using jOOQ
Pretty much any reading from Vlad Mihalcea will give you insights of this topic, plus JPA and Hibernate in general.
I am trying to insert items in a list in a database as single values in rows with the name of the sender. I am able to send the payload and insert into a single row with the user detailst. How can I loop through the payload sent and insert all the items into individual rows? I have tried to look for examples no luck. So far I can only insert as a single row in the database
this is the payload
{"labsigned":["234568","234567","2345678","2344556","12335677","2345677","234556","234545"]}
My controller
#RequestMapping(path = "/labreport/createrordispatched", method = RequestMethod.POST)
public ResponseEntity<?> createDispatched(#RequestBody Dispatched dispatched){
if(labDashboardService.createDispatched(dispatched)) {
return ResponseEntity.status(HttpStatus.CREATED).body(true);
}
return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(false);
}
My Service
public boolean createDispatched(Dispatched dispatched) {
dispatched.setCreatedBy(getCurrentUserEmail());
dispatched.setDateCreated(System.currentTimeMillis());
Dispatched ticket = new Dispatched(
dispatched.getCreatedBy(),
dispatched.getDateCreated(),
dispatched.getlabsigned()
);
dispatchedRepository.save(ticket);
return false;
}
My Model
#Entity
#Table(name = "DISPATCHED")
public class Dispatched {
private String id;
private String labsigned;
private Long dateCreated;
private String createdBy;
public Dispatched(){}
public Dispatched(String createdBy, Long dateCreated, String labsigned){
this.labsigned = rorlabsigned;
this.dateCreated = dateCreated;
this.createdBy = createdBy;
}
Assuming that you were able to insert all labsigned in the payload into one single row with the code you mentioned in the question, You should iterate dispatched.labsigned and insert one by one as rows to accomplish what you need. And returning false at the end of method createDispatched will always return HttpStatus.BAD_REQUEST even though the records are successfully saved in the DB, so you might need to change it to return true.
public boolean createDispatched(Dispatched dispatched) {
List<Dispatched> newTickets = new ArrayList<>();
dispatched.setCreatedBy(getCurrentUserEmail());
dispatched.setDateCreated(System.currentTimeMillis());
for(String labSigned:dispatched.getlabsigned()){
Dispatched ticket = new Dispatched(
dispatched.getCreatedBy(),
dispatched.getDateCreated(),
labSigned
);
newTickets.add(ticket);
}
dispatchedRepository.saveAll(newTickets);
return true;
}
Just send in a list of those values. Shouldn't have to be wrapped in a named field on an object. Just send it in as a json array like ["234568","234567","2345678","2344556","12335677","2345677","234556","234545"]. In your controller method, body don't pass it in as Dispatched but instead a List and then just loop through those creating a list of Dispatch objects and then using saveAll in the repository passing in the newly created Dispatched list.
Update: Example without actually compiling. Should be good enough for the example. Also using lombok to make it easier to read and a few other updates.
#AllArgsConstructor
#FieldDefaults(level = AccessLevel.PRIVATE, makeFinal = true)
#RestController
public class DispatchController {
DispatchedEntityFactory dispatchedEntityFactory;
DispatchedRepository dispatchedRepository;
#PostMapping("/labreport/createrordispatched")
public ResponseEntity<Boolean> createDispatched(DispatchedRequest dispatchedRequests){
List<DispatchedEntity> dispatchedEntities = dispatchedEntityFactory.creatMultipleFromDispatchRequest(dispatchedRequests);
if(CollectionUtils.isEmpty(dispatchedEntities)) {
return ResponseEntity.badRequest().body(false);
}
dispatchedRepository.saveAll(dispatchedEntities);
return ResponseEntity.ok(true);
}
}
#Value
public class DispatchedRequest {
String id;
List<String>labsigned;
Long dateCreated;
String createdBy;
}
#Entity
#Table(name = "DISPATCHED")
#Data
#FieldDefaults(level = AccessLevel.PRIVATE)
public class DispatchedEntity {
String id;
String labsigned;
Long dateCreated;
String createdBy;
}
#Component
public class DispatchedEntityFactory {
public List<DispatchedEntity> creatMultipleFromDispatchRequest(final DispatchedRequest dispatchedRequest) {
List<DispatchedEntity> dispatchedEntities = new ArrayList<DispatchedEntity>();
for(String labsignature : dispatchedRequest.getLabsigned()) {
DispatchedEntity dispatchedEntity = new DispatchedEntity(dispatchedRequest.getId(),labsignature, dispatchedRequest.getDateCreated(), dispatchedRequest.getCreatedBy());
dispatchedEntities.add(dispatchedEntity);
}
return dispatchedEntities;
}
}
I'm having a hard times figuring out how to do update scenario in Play 2 Java
I have
User.java model
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
public Long id;
#Constraints.Required
public String email;
#Constraints.Required
public String fullname;
}
And I want to update it, so in my controller I do
public Result update(Long id) {
ObjectNode result = Json.newObject();
User employee = userService.get(id);
Form<User> userForm = formFactory.form(User.class).fill(employee);
// This won't trigger validation because it uses fill() not bind()
if (userForm.hasError()) {
result.set("message", userForm.errorsAsJson());
return badRequest(result);
}
// do update here
}
Then I try to some different approach like this
public Result update(Long id) {
ObjectNode result = Json.newObject();
User employee = userService.get(id);
Form<User> userForm = formFactory.form(User.class).fill(employee);
userForm = userForm.bindFromRequest();
// This will trigger validation but bindFromRequest will override my fill(employee) before.
if (userForm.hasError()) {
result.set("message", userForm.errorsAsJson());
return badRequest(result);
}
// do update here
}
The bindFromRequest() above will override my fill(employee). I don't want to do that because when in my request I just want to fill fullname and not my email, my email property will trigger its required validation.
So my question is, how can I only update my fullname attribute with the form i fill using existing value and still triggering validation constraints from my model?
Change userForm = userForm.bindFromRequest(); to userForm.bindFromRequest();
I have working code very similar to yours and this is the only difference I've observed.
Given the following example POJO's: (Assume Getters and Setters for all properties)
class User {
String user_name;
String display_name;
}
class Message {
String title;
String question;
User user;
}
One can easily query a database (postgres in my case) and populate a list of Message classes using a BeanPropertyRowMapper where the db field matched the property in the POJO: (Assume the DB tables have corresponding fields to the POJO properties).
NamedParameterDatbase.query("SELECT * FROM message", new BeanPropertyRowMapper(Message.class));
I'm wondering - is there a convenient way to construct a single query and / or create a row mapper in such a way to also populate the properties of the inner 'user' POJO within the message.
That is, Some syntatical magic where each result row in the query:
SELECT * FROM message, user WHERE user_id = message_id
Produce a list of Message with the associated User populated
Use Case:
Ultimately, the classes are passed back as a serialised object from a Spring Controller, the classes are nested so that the resulting JSON / XML has a decent structure.
At the moment, this situation is resolved by executing two queries and manually setting the user property of each message in a loop. Useable, but I imagine a more elegant way should be possible.
Update : Solution Used -
Kudos to #Will Keeling for inspiration for the answer with use of the custom row mapper - My solution adds the addition of bean property maps in order to automate the field assignments.
The caveat is structuring the query so that the relevant table names are prefixed (however there is no standard convention to do this so the query is built programatically):
SELECT title AS "message.title", question AS "message.question", user_name AS "user.user_name", display_name AS "user.display_name" FROM message, user WHERE user_id = message_id
The custom row mapper then creates several bean maps and sets their properties based on the prefix of the column: (using meta data to get the column name).
public Object mapRow(ResultSet rs, int i) throws SQLException {
HashMap<String, BeanMap> beans_by_name = new HashMap();
beans_by_name.put("message", BeanMap.create(new Message()));
beans_by_name.put("user", BeanMap.create(new User()));
ResultSetMetaData resultSetMetaData = rs.getMetaData();
for (int colnum = 1; colnum <= resultSetMetaData.getColumnCount(); colnum++) {
String table = resultSetMetaData.getColumnName(colnum).split("\\.")[0];
String field = resultSetMetaData.getColumnName(colnum).split("\\.")[1];
BeanMap beanMap = beans_by_name.get(table);
if (rs.getObject(colnum) != null) {
beanMap.put(field, rs.getObject(colnum));
}
}
Message m = (Task)beans_by_name.get("message").getBean();
m.setUser((User)beans_by_name.get("user").getBean());
return m;
}
Again, this might seem like overkill for a two class join but the IRL use case involves multiple tables with tens of fields.
Perhaps you could pass in a custom RowMapper that could map each row of an aggregate join query (between message and user) to a Message and nested User. Something like this:
List<Message> messages = jdbcTemplate.query("SELECT * FROM message m, user u WHERE u.message_id = m.message_id", new RowMapper<Message>() {
#Override
public Message mapRow(ResultSet rs, int rowNum) throws SQLException {
Message message = new Message();
message.setTitle(rs.getString(1));
message.setQuestion(rs.getString(2));
User user = new User();
user.setUserName(rs.getString(3));
user.setDisplayName(rs.getString(4));
message.setUser(user);
return message;
}
});
A bit late to the party however I found this when I was googling the same question and I found a different solution that may be favorable for others in the future.
Unfortunately there is not a native way to achieve the nested scenario without making a customer RowMapper. However I will share an easier way to make said custom RowMapper than some of the other solutions here.
Given your scenario you can do the following:
class User {
String user_name;
String display_name;
}
class Message {
String title;
String question;
User user;
}
public class MessageRowMapper implements RowMapper<Message> {
#Override
public Message mapRow(ResultSet rs, int rowNum) throws SQLException {
User user = (new BeanPropertyRowMapper<>(User.class)).mapRow(rs,rowNum);
Message message = (new BeanPropertyRowMapper<>(Message.class)).mapRow(rs,rowNum);
message.setUser(user);
return message;
}
}
The key thing to remember with BeanPropertyRowMapper is that you have to follow the naming of your columns and the properties of your class members to the letter with the following exceptions (see Spring Documentation):
column names are aliased exactly
column names with underscores will be converted into "camel" case (ie. MY_COLUMN_WITH_UNDERSCORES == myColumnWithUnderscores)
Spring introduced a new AutoGrowNestedPaths property into the BeanMapper interface.
As long as the SQL query formats the column names with a . separator (as before) then the Row mapper will automatically target inner objects.
With this, I created a new generic row mapper as follows:
QUERY:
SELECT title AS "message.title", question AS "message.question", user_name AS "user.user_name", display_name AS "user.display_name" FROM message, user WHERE user_id = message_id
ROW MAPPER:
package nested_row_mapper;
import org.springframework.beans.*;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.support.JdbcUtils;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
public class NestedRowMapper<T> implements RowMapper<T> {
private Class<T> mappedClass;
public NestedRowMapper(Class<T> mappedClass) {
this.mappedClass = mappedClass;
}
#Override
public T mapRow(ResultSet rs, int rowNum) throws SQLException {
T mappedObject = BeanUtils.instantiate(this.mappedClass);
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(mappedObject);
bw.setAutoGrowNestedPaths(true);
ResultSetMetaData meta_data = rs.getMetaData();
int columnCount = meta_data.getColumnCount();
for (int index = 1; index <= columnCount; index++) {
try {
String column = JdbcUtils.lookupColumnName(meta_data, index);
Object value = JdbcUtils.getResultSetValue(rs, index, Class.forName(meta_data.getColumnClassName(index)));
bw.setPropertyValue(column, value);
} catch (TypeMismatchException | NotWritablePropertyException | ClassNotFoundException e) {
// Ignore
}
}
return mappedObject;
}
}
Update: 10/4/2015. I typically don't do any of this rowmapping anymore. You can accomplish selective JSON representation much more elegantly via annotations. See this gist.
I spent the better part of a full day trying to figure this out for my case of 3-layer nested objects and just finally nailed it. Here's my situation:
Accounts (i.e. users) --1tomany--> Roles --1tomany--> views (user is allowed to see)
(These POJO classes are pasted at the very bottom.)
And I wanted the controller to return an object like this:
[ {
"id" : 3,
"email" : "catchall#sdcl.org",
"password" : "sdclpass",
"org" : "Super-duper Candy Lab",
"role" : {
"id" : 2,
"name" : "ADMIN",
"views" : [ "viewPublicReports", "viewAllOrders", "viewProducts", "orderProducts", "viewOfferings", "viewMyData", "viewAllData", "home", "viewMyOrders", "manageUsers" ]
}
}, {
"id" : 5,
"email" : "catchall#stereolab.com",
"password" : "stereopass",
"org" : "Stereolab",
"role" : {
"id" : 1,
"name" : "USER",
"views" : [ "viewPublicReports", "viewProducts", "orderProducts", "viewOfferings", "viewMyData", "home", "viewMyOrders" ]
}
}, {
"id" : 6,
"email" : "catchall#ukmedschool.com",
"password" : "ukmedpass",
"org" : "University of Kentucky College of Medicine",
"role" : {
"id" : 2,
"name" : "ADMIN",
"views" : [ "viewPublicReports", "viewAllOrders", "viewProducts", "orderProducts", "viewOfferings", "viewMyData", "viewAllData", "home", "viewMyOrders", "manageUsers" ]
}
} ]
A key point is to realize that Spring doesn't just do all this automatically for you. If you just ask it to return an Account item without doing the work of nested objects, you'll merely get:
{
"id" : 6,
"email" : "catchall#ukmedschool.com",
"password" : "ukmedpass",
"org" : "University of Kentucky College of Medicine",
"role" : null
}
So, first, create your 3-table SQL JOIN query and make sure you're getting all the data you need. Here's mine, as it appears in my Controller:
#PreAuthorize("hasAuthority('ROLE_ADMIN')")
#RequestMapping("/accounts")
public List<Account> getAllAccounts3()
{
List<Account> accounts = jdbcTemplate.query("SELECT Account.id, Account.password, Account.org, Account.email, Account.role_for_this_account, Role.id AS roleid, Role.name AS rolename, role_views.role_id, role_views.views FROM Account JOIN Role on Account.role_for_this_account=Role.id JOIN role_views on Role.id=role_views.role_id", new AccountExtractor() {});
return accounts;
}
Note that I'm JOINing 3 tables. Now create a RowSetExtractor class to put the nested objects together. The above examples show 2-layer nesting... this one goes a step further and does 3 levels. Note that I'm having to maintain the second-layer object in a map as well.
public class AccountExtractor implements ResultSetExtractor<List<Account>>{
#Override
public List<Account> extractData(ResultSet rs) throws SQLException, DataAccessException {
Map<Long, Account> accountmap = new HashMap<Long, Account>();
Map<Long, Role> rolemap = new HashMap<Long, Role>();
// loop through the JOINed resultset. If the account ID hasn't been seen before, create a new Account object.
// In either case, add the role to the account. Also maintain a map of Roles and add view (strings) to them when encountered.
Set<String> views = null;
while (rs.next())
{
Long id = rs.getLong("id");
Account account = accountmap.get(id);
if(account == null)
{
account = new Account();
account.setId(id);
account.setPassword(rs.getString("password"));
account.setEmail(rs.getString("email"));
account.setOrg(rs.getString("org"));
accountmap.put(id, account);
}
Long roleid = rs.getLong("roleid");
Role role = rolemap.get(roleid);
if(role == null)
{
role = new Role();
role.setId(rs.getLong("roleid"));
role.setName(rs.getString("rolename"));
views = new HashSet<String>();
rolemap.put(roleid, role);
}
else
{
views = role.getViews();
views.add(rs.getString("views"));
}
views.add(rs.getString("views"));
role.setViews(views);
account.setRole(role);
}
return new ArrayList<Account>(accountmap.values());
}
}
And this gives the desired output. POJOs below for reference. Note the #ElementCollection Set views in the Role class. This is what automatically generates the role_views table as referenced in the SQL query. Knowing that table exists, its name and its field names is crucial to getting the SQL query right. It feels wrong to have to know that... it seems like this should be more automagic -- isn't that what Spring is for?... but I couldn't figure out a better way. You've got to do the work manually in this case, as far as I can tell.
#Entity
public class Account implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private long id;
#Column(unique=true, nullable=false)
private String email;
#Column(nullable = false)
private String password;
#Column(nullable = false)
private String org;
private String phone;
#ManyToOne(fetch = FetchType.EAGER, optional = false)
#JoinColumn(name = "roleForThisAccount") // #JoinColumn means this side is the *owner* of the relationship. In general, the "many" side should be the owner, or so I read.
private Role role;
public Account() {}
public Account(String email, String password, Role role, String org)
{
this.email = email;
this.password = password;
this.org = org;
this.role = role;
}
// getters and setters omitted
}
#Entity
public class Role implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private long id; // required
#Column(nullable = false)
#Pattern(regexp="(ADMIN|USER)")
private String name; // required
#Column
#ElementCollection(targetClass=String.class)
private Set<String> views;
#OneToMany(mappedBy="role")
private List<Account> accountsWithThisRole;
public Role() {}
// constructor with required fields
public Role(String name)
{
this.name = name;
views = new HashSet<String>();
// both USER and ADMIN
views.add("home");
views.add("viewOfferings");
views.add("viewPublicReports");
views.add("viewProducts");
views.add("orderProducts");
views.add("viewMyOrders");
views.add("viewMyData");
// ADMIN ONLY
if(name.equals("ADMIN"))
{
views.add("viewAllOrders");
views.add("viewAllData");
views.add("manageUsers");
}
}
public long getId() { return this.id;}
public void setId(long id) { this.id = id; };
public String getName() { return this.name; }
public void setName(String name) { this.name = name; }
public Set<String> getViews() { return this.views; }
public void setViews(Set<String> views) { this.views = views; };
}
I worked a lot on stuff like this and do not see an elegant way to achieve this without an OR mapper.
Any simple solution based on reflection would heavily rely on the 1:1 (or maybe N:1) relation. Further your columns returned are not qualified by their type, so you cannot say which columns matches which class.
You may get away with spring-data and QueryDSL. I did not dig into them, but I think you need some meta-data for the query that is later used to map back the columns from your database into a proper data structure.
You may also try the new PostgreSQL json support that looks promising.
NestedRowMapper worked for me, the important part is getting the SQL correct. The Message properties shouldn't have the class name in them so the query should look like this:
QUERY:
SELECT title AS "title", question AS "question", user_name AS "user.user_name", display_name AS "user.display_name" FROM message, user WHERE user_id = message_id