REST to return content after POST on Java service

Question

New users are created with the POST method, and after this the database will attach it an unique ID, which is necessary to create a token.

The only way to create a token, is after the process of user creation. I query it from the database and now it should have ID on it, but I can't figure how to do that.

Is there any way to retrieve the entity from database right after creating it?

If looked at this similar question, but couldn't find an answer: Is it ok by REST to return content after POST?

@POST
    @Consumes({MediaType.APPLICATION_JSON})
    public Response create(@QueryParam("email") String email, @QueryParam("username") String userName, @QueryParam("password") String password) {
        if (TextUtil.isEmpty(userName) || TextUtil.isEmpty(password) || TextUtil.isEmpty(email)) {
            return Response.status(Response.Status.BAD_REQUEST).build();
        } else {
            User newUser = new User();
            newUser.setEmail(email);
            newUser.setUsername(userName);
            newUser.setPass(password);
            super.create(newUser); //ths line create user in database
            String id = newUser.getUid() + ""; //the newUser has no id yet so it is null but I want this id from database
            return Response.status(Response.Status.OK).entity("id: " + id).build(); 
        }   
    }

Create super.method

public void create(T entity) {
        getEntityManager().persist(entity);
    }

I generate REST api using this tutorial https://netbeans.org/kb/docs/websvc/rest.html

``` super.create(newUser); super.getEntityManager().flush(); super.getEntityManager().find(User.class, newUser.getUId()) ``` — Rafael Guillen, Nov 16 '17 at 13:46
Make your create function return the user instead of void. In your method you would then create the user and then get it and return it. — Valentin Grégoire, Nov 16 '17 at 13:51
note that newUser.getUd() is null because the id is only created in database. I use auto increment id in database — coinhndp, Nov 16 '17 at 13:51
the problem is that I can not get the user cause' I do not have its id — coinhndp, Nov 16 '17 at 13:51
Use the code in my previous comment to sync the EntityManager with the database. — Rafael Guillen, Nov 16 '17 at 13:53
getUId return null because the id is only created in my database — coinhndp, Nov 16 '17 at 15:09

score 0 · Answer 1 · answered Nov 16 '17 at 13:54

0

getEntityManager().persist(entity);

Set the id of the entity by calling entity.setId(...).

answered Nov 16 '17 at 13:54

Peter Rader

237
3
14

I set id in database by using auto increment. How can I set id by code? I cannot set it mannually right? – coinhndp Nov 16 '17 at 13:57

score 0 · Answer 2 · answered Nov 16 '17 at 13:56

0

I my comments I show how to sync EntityManager. Maybe you should write a better create method:

public <T> T create(T t) throws Exception {

        try {
            entityManager.persist(t);
            entityManager.flush();
        } catch (Exception e) {
            throw e;
        } finally {
            entityManager.clear();
        }

        return t;
    }

And then

newUser = super.create(newUser);

answered Nov 16 '17 at 13:56

Rafael Guillen

1,343
10
25

the newUser does not have an Id because the id is only created in database – coinhndp Nov 16 '17 at 16:52
When `entityManager.flush();` is called, all changes are written to the database and the Ids defined in JPA are generated. How do you generate the UId field of User? – Rafael Guillen Nov 16 '17 at 17:20
I generate it in database by using auto increment. If id is null then it auto generates an id for my user. How should I generate id? I use mySQL – coinhndp Nov 16 '17 at 17:39
UId field or getter should have `@Id` and `@Autogenerated` annotations, look here https://stackoverflow.com/questions/4102449/how-to-annotate-mysql-autoincrement-field-with-jpa-annotations or here https://stackoverflow.com/questions/25047226/jpa-generationtype-auto-not-considering-column-with-auto-increment for more details – Rafael Guillen Nov 16 '17 at 17:43
Yes I had it. Look at my code above and you can see I have getUId but it is null (in the database it is not null but in newUser object it is null). Thats my problem – coinhndp Nov 16 '17 at 17:53

REST to return content after POST on Java service

2 Answers2