thanks Jason - I'll need to think more about how this would work in my case.
It sounds like I'll be able to query that new kind (return all the Campaign keys for a FundingOrganization of "ABC") to get a collection of keys. But then if I wanted to extract only the entities from that result that meet certain criteria (Campaign.Duration > 30) , I'll need to do that outside of the query language. I'm sure my questions reflect a newness to OOD. I do appreciate your response. Hans On Nov 2, 3:27 pm, "Jason (Google)" <[email protected]> wrote: > Hi Hans. Aside from the article on modeling entity relationships and the JDO ... > > It sounds like you want to add a new kind (as opposed to a new property for > an existing kind) and establish a relationship with this new kind > (FundingOrganization) and an existing kind (Campaign). For many-to-many > relationships such as this, one approach you can take is similar to what you > might do for an RDBMS schema: introduce a new table (kind) to model the > relationship between FundingOrganization and Campaign entities. This third > kind would have only two properties, one storing a FundingOrganization Key > and the other a Campaign Key, then you can use it to query for all > FundingOrganization entities associated with a given Campaign and vice > versa. This approach doesn't require you to modify your Campaign kind at > all, so you don't necessarily need to make it aware of the > FundingOrganization kind, which was one of your requirements. > > Let me know if this answers your question or if you have any other > questions. > > - Jason > > On Thu, Oct 29, 2009 at 1:55 PM, Hans <[email protected]> wrote: > > > Hoping someone might help me with a somewhat OT question. > > > I developed an object model for a GAE/J application that worked fairly ... > > Can someone point this rookie to intro material/URLs for building and > > refactoring designs that lend themselves to these type of changes? I'm > > looking for info on adaptable design, especially when you're using a > > datastore and not using a RDBMS, junction tables, etc. > > > thanks, > > Hans > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en -~----------~----~----~----~------~----~------~--~---
