Hql query using dot´s in the response parameters - sql

Question

I am accesing to the database using a Dto with some entities and I want to improve the request without modifing my dto and removing the fetch so hibernate don´t return all the data from all the entities (hibernate is set to lazy), I tried with the next, but it´s not working:
StringBuilder hql = new StringBuilder();
hql.append(" select d.id as id, ce.cod as clasification.cod ");
hql.append(" from Document d");
hql.append(" join d.clasificacionEntity ce");
The working hql request:
StringBuilder hql = new StringBuilder();
hql.append(" select d");
hql.append(" from Document d");
hql.append(" join fetch d.clasificacionEntity ce");
The problem is when I try to use "ce.cod as clasification.cod" the second dot gives me a error, there is other way to do that? , thanks a lot!!!
My dto result is:
DocumentDto{
private id
private clasificacionEntityDto;
}
And
clasificacionEntityDto {
private cod
}

Answer 1

When you write this code:
hql.append(" select d.id as id, ce.cod as clasification.cod ");
You tell on parser d.id named id and ce.cod named clasification.cod
The last alias is wrong! A correct name is clasification or cod.
If you want to point properties of ce.cod (cod which data type has?) you can point after extraction of your result.

Answer 2

You don't mention how you are transforming the query result into your DTO entities. One simple solution that does not require you to alter your DTO classes.
// select only the fields you need from your query
StringBuilder hql = new StringBuilder();
hql.append(" select d.id as id, ce.cod as cod ");
hql.append(" from Document d");
hql.append(" join d.clasificacionEntity ce");
// ... etc. Then get back your results as raw type
List<Object[]> rows = crit.list();
Then loop through your results and create your DTOs manually. Note that this example assumes that your document has a single classification.
List<DocumentDTO> documents = new ArrayList<DocumentDTO>();
for ( Object[] row: rows ) {
Long id = (Long)row[0];
String cod = (String)row[1];
ClassificationEntityDTO ce = new ClassificationEntityDTO(cod);
DocumentDTO d = new DocumentDTO(id, ce);
documents.add(d);
}
See this question
AliasToBeanResultTransformer(MyDTO.class) fails to instantiate MyDTO

Answer 3

At the end I just create a dto like this:
DocumentDto{
private id
private String clasificacionEntityDtoCod;
}
and set it like this:
StringBuilder hql = new StringBuilder();
hql.append(" select d.id as id, ce.cod as clasificacionEntityDtoCod ");
hql.append(" from Document d");
hql.append(" join d.clasificacionEntity ce");