Resolve JPA Criteria Builder org.hibernate.QueryException: could not instantiate class from tuple

Removed

Using Criteria Builder in JPA, I construct a bean from the query result using this line:

query.select(builder.construct(MyNewBean.class, root));

I give here the root and not root.get("colName"), as I have difficulties in generating queries as I like. I will speak about that later. But now let us focus on the first problem.

While testing my code, I get

org.hibernate.QueryException: could not instantiate class className from tuple
at org.hibernate.transform.AliasToBeanConstructorResultTransformer.transformTuple
I have thought first that I shouldn't give root (as I was used to give root.get("user").get("name"), root.get("phone")). But the problems wasn't really that.
Just after reading again the error, I have found this :
Caused by: java.lang.NullPointerException

OK. The Problem is in my constructor. I do
this.userName = MyEntity.get("user").get("name");

In fact, User refers to  another entity, so when we get the user, it can be NULL. Which will generate the nullPointerException and thus the tuple Error. So before getting the entities attributes make sure that they are not null (No need to check that for the NOT NULL foreign Keys)

if( MyEntity.get("user") != null){
   this.userName = MyEntity.get("user").get("name");
}

An advice is to use also an EAGER fetch if you are sure that you need the parameters (to return to a Web Service Client). So, only one request will be generated. If you use a Lazy join, at every call to get, a new Select will be done which will degrade performance.