# Help with modelling ActiveRecord associations **URL:** \ **Category:** Rails\ **Created:** [May 28, 2007, 4:45pm UTC](https://www.ruby-forum.com/t/help-with-modelling-activerecord-associations/105297 "2007-05-28T16:45:34Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![croxmeister](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/53a042/32.png) [@croxmeister](https://www.ruby-forum.com/u/croxmeister)\ **Post date:** [May 28, 2007, 4:45pm UTC](https://www.ruby-forum.com/t/help-with-modelling-activerecord-associations/105297/1 "2007-05-28T16:45:34Z")
I have been messing about with Rails and ActiveRecord for a while now, and I have had great success in the simple cases. But I have hit a stumbling block when it came to modelling a non-trivial problem domain. I had hoped to absorb the knowledge by example, but fundamentally I don’t grok the more sophisticated associations and more importantly when to use them. My background isn’t in DB designs. I went looking for something that could help me with the design related stuff from an ActiveRecord perspective (i.e. I know what I want my objects to look like and behave in terms of their associations, but how do I model that in the database). Anyone know of any domain modelling resources with an ActiveRecord flavour? Preferably example heavy. I suspect that I need to get down and dirty with HABTM, or has\_many through, but I don’t know when I need to use them. If its any use, the problem I am trying to model is as follows. Its a software & hardware inventory system, services run on regular PCs but have a relationship with hardware devices. All are network accessible, but the hardware devices can have a relationship with hundreds of services, while the services can have a relationship with at most 6 hardware devices (domain specific constraints). any help at all would be appreciated. regards, Richard.