How do we modify an HQL transformer when loading a specific parent or other property of a mapped object?

Question

This is an important addition, especially to solve performance problems, allowing you to write efficient dynamic HQL queries.

But how can we change the HQL transformer when loading a specific parent or other property of the associated object?

The following code:

session.createQuery( "select st.stNumber as stNumber, st.stDate as stDate " + " from SomeTable st " + " where st.someTableId < 1000") .setResultTransformer( Transformers.aliasToBean(database.SomeTable.class)) .list(); 

works fine, but what if I want to load only some of the properties of his parents?

For example, let's say SomeTable has a parent called SomedParent , and I want to access only one of the fields of this parent?

 session.createQuery( "select st.stNumber as stNumber, st.stDate as stDate, st.someParent.someParentField as someParentField " + " from SomeTable st " + " where st.someTableId < 1000") .setResultTransformer( Transformers.aliasToBean(database.SomeTable.class)) .list(); 

So any ideas?

Answer 1

You are almost right.

First you create SomeTable :

 class SomeTable { private Long stNumber; private Date stDate; private String someParentField; //getters and setters } 

And your request:

 session.createQuery( "select st.stNumber as stNumber, st.stDate as stDate, someParent.someParentField as someParentField " + " from SomeTable st " + " JOIN st.someParent someParent" + " where st.someTableId < 1000") .setResultTransformer( Transformers.aliasToBean(SomeTable.class)) .list();