how to make a ejbql query from an entity bean ?

[vlaugier]

Hello,

I would like to perform ejbql queries from the entity beans. This way I could customize my getters and add some very handy transient methods.

Is there a way to do this ?

I have tries to declare an entityManager in the different fashion :

@PersistenceContext
EntityManager em;


@PersistenceContext(type=EXTENDED)
EntityManager em;

@In
EntityManager em;


But I get

Caused by: java.lang.IllegalArgumentException: @PersistenceContext may only be used on session bean or message driven bean components: employee

Does anyone has ever managed to do this ?

regards

Vincent

[pmuir]

Its not good practice to do this (I'm sure Gavin has some blogs on this, so go look on http://in.relation.to) but if you have to you would have to look up the EM programatically.

[supernovasoftware.com]

I use @Formula. It requires compile time instrumentation for lazy loading and will not load collections unless you use hibernate mapping files. It works fine with calculated properties and annotations as shown below.

See:
http://opensource.atlassian.com/projects/hibernate/browse/ANN-210

It works well and you can even use the properties in HQL.

Example:

private Double baseCostPerFt;
 @Basic(fetch = FetchType.LAZY)
 @Formula(value="( select v.basecostperft from v_item_calc v where v.id = id )")
 public Double getBaseCostPerFt() { return baseCostPerFt; }
 public void setBaseCostPerFt(Double baseCostPerFt) { this.baseCostPerFt = baseCostPerFt; }

HQL:

select i from Item i where i.baseCostPerFt>10.59