Map entity using query in Hibernate

Question

consider table

sales (id, seller_id, amount, date)

and here is a view that is generated from sales using query SELECT seller_id, SUM(amount) FROM sales GROUP BY seller_id

total_sales (seller_id, amount)

I want to make an entity for total sales but without the view on the sql side.

This entity will be constructed from a query. The closest thing I found is this, but I could not make it work.

Even if I define the loader, hibernate looks for the entity's table and gives an error if it cannot find it. If I create the table it does not load the entity from the named query I defined, Hibernate generates the query itself.

Is there a way to make @Loader to work or is there another way that I can map a query to entity?

Answer 1

Why don't you just use new in the query?

select new TotalSales(seller_id, count(seller_id))
from sales
group by seller_id

You just write a class TotalSales with a constructor taking the seller_id and an integer.

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Edit: When using criteria API, you can use the AliasToBeanResultTransformer (See API docs). It copies every alias name to a property of the same name.

 List list = s.createCriteria(Sales.class)
  .setProjection(Projections.projectionList()
    .add( Projections.property("id"), "SellerId" )
    .add( Projections.rowCount("id"), "Count" ) )
  .setResultTransformer( 
    new AliasToBeanResultTransformer(TotalSales.class) )
  .list();

Then your TotalSales needs a SellerId and Count property.