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Entity Modeller - Setting Up Many-to-Many Relationships: Link Entities(?)
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Entity Modeller - Setting Up Many-to-Many Relationships: Link Entities(?)


  • Subject: Entity Modeller - Setting Up Many-to-Many Relationships: Link Entities(?)
  • From: Tim Kitchener <email@hidden>
  • Date: Fri, 6 Feb 2009 11:26:08 +0000

Hi all,

I'm a fairly infrequent dabbler into WO having only written a couple of applications with relatively simple database models with standard 1-to-many relationships.  Whilst writing these I've found plenty of useful documentation at: http://developer.apple.com/documentation/WebObjects/ but nothing really that covers what I'm trying to do in this new bigger system:

I'm sure many of you have implemented models of a similar principal and would really appreciate it if you could take the time to produce me an idiots'-guide to set this up. 

The scenario that I need to model for our current project requires many-to-many relationship between my entities.  I have an Entity A (representing a users' account) and Entity B (representing an object the user is interested in).  A user account may be interesting in many objects, and an object may have many user accounts interested in it, which, correct me if I'm wrong, requires a many-to-many relationship.  From what I remember of the dim and distant past of Database design at Uni, the solution is a link entity that sits between Entity A and Entity B with a compound PK of Entity A and Entity B PK.

I've tried to model this in Entity Modeller in Eclipse, and it exceptions(!?):



This scenario is repeated a couple of times throughout my current design, so I'd like to get it set up about right the first time.

Any and all advice will be appreciated.  As I said, I don't spend a huge amount of time developing in WO, so don't worry about offending me by pointing out I've got completely the wrong end of the stick and am making all sorts of misassumptions.

Thanks in advanced,


-- Tim
KennettNet Software Limited
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