How about something like:
ObjRelationship rel = Cayenne.getObjEntity( employee ).getAnyRelationship(
company ).getReverseRelationship();
Jurgen
-----Original Message-----
From: Maik Musall
Sent: Monday, March 19, 2018 3:41 PM
To: user@cayenne.apache.org
Subject: Re: Fetching a to-many DbRelationship
I have cases of this like a reference to the user that created an object.
Over the years, those become millions of objects, so if the application
would somehow stumble upon the back-relationship and try to resolve 1:n with
millions of objects, it would stall for a while, crossing the threshold to
be qualified as a bug. By not modeling those relationships, the entire bug
class is avoided.
I can always construct a manual query that fetches the objects should I ever
need them, but of course I can apply a proper expression with that to filter
the data.
What I'd love to have is a way to find out what types even have a
relationship to users, despite not having the back-relationship modeled, so
the user's ObjEntity doesn't know about it. (Short of iterating over all
entities and all their relationships of course.)
Am 19.03.2018 um 14:29 schrieb Michael Gentry <blackn...@gmail.com>:
I wouldn't think having company->>employees modeled would cause a
performance issue. Did you try it first and then remove it?
On Mon, Mar 19, 2018 at 8:39 AM, Hugi Thordarson <h...@karlmenn.is> wrote:
No, I only have a DbRelationship so no code gets generated. The
ObjRelationship is only modeled in one direction for performance reasons.
Imagine a relationship Company <----->> Employees where both
DbRelationships are modeled but only "Emploee" has a "company"
relationship, "Company" has no "employees" relationship—but now I want to
get a company's employees.
Conceptually, something along the lines of company.readProperty(
"db:employees" ) but obviously that doesn't work.
I know I can manually extract the PK from the Company and perform a brute
force search on Employees, but since I have a modeled DbRelationship I
imagined there's something a bit higher level.
- hugi
On 19 Mar 2018, at 12:32, Michael Gentry <blackn...@gmail.com> wrote:
Hi Hugi,
Do you mean something like lineItem.getOrders(); ?
On Mon, Mar 19, 2018 at 7:06 AM, Hugi Thordarson <h...@karlmenn.is>
wrote:
Hi all,
I feel like this is something I should know so I'm almost hesitant to
ask.
But…
I have a DataObject - how do I read the value of a ToMany
DbRelationship
it has?
Cheers,
- hugi
