Re: [eclipselink-users] Getting sub-collection in SELECT statement

[Tom Ware <tom.ware@xxxxxxxxxx>]

Hi Jan,

  To select across a relationship (e.g. r.nodeEntity) you are going to want to 
use a ReportQuery instead of a ReadAllQuery.

  Here is an example ReportQuery that does something similar to what you are 
looking for:

(Employee has a 1-1 relationship with manager.  This query will select an 
Employee's manager)

    ReportQuery reportQuery = new ReportQuery();
// This will give you a list of managers instead of of a ReportQueryResult instance
    reportQuery.returnWithoutReportQueryResult();
    reportQuery.setReferenceClass(Employee.class);
    ExpressionBuilder empbuilder = new ExpressionBuilder();
    reportQuery.addAttribute("manager",empbuilder.get("manager"));
    reportQuery.setSelectionCriteria(empbuilder.get("salary").greaterThan(100000));

-Tom

ossaert wrote:
> Hi,
>  
> I have probably a stupid question, but I don't seem to find the answer in
> the documentation.
>  
> I have an entity called RelationNodeEntity. There I have a foreign key to
> NodeEntity and RelationNodeEntity along with other properties. Anyway, I
> want to load the NodeEntity when RelationNodeEntity complies to certain
> parameters.
>  
> I have this example code (snippet):
>  
> Expression relatioNodeExpression = new
> ExpressionBuilder(RelationNodeEntity.class);
>         
> Expression step1 = 
>                
> relatioNodeExpression.get(RelationNodeEntity.FIELD_RELATION).
>                
> get(RelationEntity.FIELD_ID).equal(relationEntity.getRelationId());
>         
> Expression step2 = step1.and(... other expression - irrelevant);
>         
> ReadAllQuery query = new ReadAllQuery(RelationNodeEntity.class, step2);
>  
> But then I get the RelationNodeEntities. How can I change the SELECT
> statement that the query only selects the NodeEntity object? It works in
> EQL, there I write "SELECT r.nodeEntity FROM RelationNodeEntity r". What am
> I doing wrong or which mistake do I make here?
>  
> Thanks,
> Jan De Cooman