Use Hibernate createNativeQuery with TypedQuery for Integer.class

Question

I want to use Hibernate TypedQuery for a NativeQuery with Integer.class argument. Is it possible?

NativeQuery<Integer> query = session.createNativeQuery("select 1 from dual", Integer.class);
query.list(); //<--Error.  Caused by: org.hibernate.MappingException: Unknown entity: java.lang.Integer

or

query.getResultList(); //<--Error. Caused by: org.hibernate.MappingException: Unknown entity: java.lang.Integer

or

query.getSingleResult(); //<--Error. Caused by: org.hibernate.MappingException: Unknown entity: java.lang.Integer

I've found some examples on Web that suggest, this is theoretically possible.

see getTaskCount()

Update 1: I've updated the example.

Update 2: Add getSingleResult() example.

coladict · Accepted Answer · 2019-02-14 08:38:50Z

3

The resultClass parameter only accepts entity classes.

Also, when using native queries you are never guaranteed what what the return type for numbers will be, so using Integer or Long in a typecast will often blow-up on you when it's java.math.BigInteger.

What you need to do is:

Query query = em.createNativeQuery("select 1 from dual");  
Number nval = (Number) query.getSingleResult(); 
Integer val = nval == null ? null : nval.intValue();

Or for a list:

Query query = em.createNativeQuery("select 1 from dual");
List<Number> l = (List<Number>) query.getResultList();
for (Number nval : l) {
    Integer val = nval == null ? null : nval.intValue();
    // do stuff
}

answered Feb 14, 2019 at 8:38

coladict

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2 Comments

Tony Over a year ago

Thank you for your answer. But have you seen an example link? They are using Long.class as resultClass parameter.

Tony Over a year ago

Now I see they are using Query and not NativeQuery.

sgraton · Accepted Answer · 2019-02-13 18:55:08Z

2

Second parameter of createNativeQuery() should be a mapped entity. Integer is not. So you have to do :

Query query = em.createNativeQuery("select 1 from dual");  
Integer val = (Integer) query.getSingleResult();

edited Feb 13, 2019 at 18:55

answered Feb 12, 2019 at 18:54

sgraton

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1 Comment

Tony Over a year ago

Sorry, but that's not quite true. I can use list() on query with only 1 result. I've updated my answer.

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