# Understanding this model relationship (possibly a HABTM and a belongs\_to ?) **URL:** \ **Category:** Rails\ **Created:** [August 11, 2010, 6:22am UTC](https://www.ruby-forum.com/t/understanding-this-model-relationship-possibly-a-habtm-and-a-belongs-to/193096 "2010-08-11T06:22:03Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Rick\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/71c47a/32.png) [@Rick\_R](https://www.ruby-forum.com/u/Rick_R)\ **Post date:** [August 11, 2010, 6:22am UTC](https://www.ruby-forum.com/t/understanding-this-model-relationship-possibly-a-habtm-and-a-belongs-to/193096/1 "2010-08-11T06:22:03Z")
I’m pretty newb and trying to get a handle on setting up a particular relationship with my models. For sake of this discussion (real app isn’t with tools but for illustration, using tools): To start with (more complicated in a bit); - A User can have multiple tools - A single tool can only belong to one ToolGroup - A User can belong to multiple ToolGroups To model this relationship, I was thinking: User has\_many :tools has\_and\_belong\_to\_many :tool\_groups Tool has\_one :tool\_group belongs\_to :user ToolGroup has\_and\_belongs\_to\_many :users So first question, is the above set up correctly? Once the above is set up correctly, I want to have it set up where a ToolGroup can also be ‘owned’ by a User. In other words, a user will set up a ToolGroup and they are the owner, but other users can belong to this ToolGroup. How do I model that? Do I need to set up another model that is called “Owner” that is really a “User”? This doesn’t seem right. In reality the db table “ToolGroup” would just need an “ownerID” that would be a fk to the User table, but I’m not sure how to model that since ToolGroup already has a HABTM to users. Can I have a HABTM to Users and also a belongs\_to :User? Thanks for any help ---
**Author:** ![Rick\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/71c47a/32.png) [@Rick\_R](https://www.ruby-forum.com/u/Rick_R)\ **Post date:** [August 11, 2010, 7:54pm UTC](https://www.ruby-forum.com/t/understanding-this-model-relationship-possibly-a-habtm-and-a-belongs-to/193096/2 "2010-08-11T19:54:02Z")
My initial example is probably confusing. Here is another shot at it in something that has more meaning: A User can create multiple “notices” ( eg “Corporate meeting notice”, “Big Sale Items”, “Job Wanted” ) A User can create multiple “notice groups” (eg “Corporate Notices”, “Public Notices”, “My Miscellaneous Notices”) Every notice should belong to an “notice group” A User needs to be able to subscribe to multiple “notice groups” so that they could see the notices in the different groups they’re subscribed to. To model this relationship, I was thinking: User has\_many :notices has\_and\_belong\_to\_many :notice\_groups Notice has\_one :notice\_group belongs\_to :user NoticeGroup has\_and\_belongs\_to\_many :users So first question, is the above set up correctly? How would I also model that a “NoticeGroup” is ‘owned/created’ by a particular user? Right now the HABTM on NoticeGroup seems to imply that the NoticeGroup can belong to many Users but I also need it to show that its owned/created by a particular User (owner\_id concept on NoticeGroup?), can I have a HABTM :users and a belongs\_to :User in the same NoticeGroup model definition? On Wed, Aug 11, 2010 at 12:20 AM, Rick R [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > - A User can belong to multiple ToolGroups > > called “Owner” that is really a “User”? This doesn’t seem right. In reality > the db table “ToolGroup” would just need an “ownerID” that would be a fk to > the User table, but I’m not sure how to model that since ToolGroup already > has a HABTM to users. Can I have a HABTM to Users and also a belongs\_to > :User? > > Thanks for any help – Rick R ---
**Author:** ![Rick\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/71c47a/32.png) [@Rick\_R](https://www.ruby-forum.com/u/Rick_R)\ **Post date:** [August 11, 2010, 8:26pm UTC](https://www.ruby-forum.com/t/understanding-this-model-relationship-possibly-a-habtm-and-a-belongs-to/193096/3 "2010-08-11T20:26:33Z")
Rick R wrote: > My initial example is probably confusing. Here is another shot at it in > something that has more meaning: > > A User can create multiple “notices” ( eg “Corporate meeting notice”, > “Big > Sale Items”, “Job Wanted” ) > A User can create multiple “notice groups” (eg “Corporate Notices”, > “Public > Notices”, “My Miscellaneous Notices”) Are these notice groups specific to the one user, or are they more like global discussion topics? Can notice groups contain notices created by users other than the one who created the group? > Every notice should belong to an “notice group” > A User needs to be able to subscribe to multiple “notice groups” so that > they could see the notices in the different groups they’re subscribed > to. > > To model this relationship, I was thinking: > > User > has\_many :notices > has\_and\_belong\_to\_many :notice\_groups > > Notice > has\_one :notice\_group That should be belongs\_to, not has\_one. > belongs\_to :user > > NoticeGroup > has\_and\_belongs\_to\_many :users > > So first question, is the above set up correctly? Maybe, maybe not. Depends on the questions above. > How would I also model that a “NoticeGroup” is ‘owned/created’ by a > particular user? Right now the HABTM on NoticeGroup seems to imply that > the > NoticeGroup can belong to many Users but I also need it to show that its > owned/created by a particular User (owner\_id concept on NoticeGroup?), > can I > have a HABTM :users and a belongs\_to :User in the same NoticeGroup model > definition? Sure. Just give the associations different names. ## Best, Marnen Laibow-Koser [http://www.marnen.org](http://www.marnen.org) removed\_email\_address@domain.invalid ---
**Author:** ![Rick\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/71c47a/32.png) [@Rick\_R](https://www.ruby-forum.com/u/Rick_R)\ **Post date:** [August 11, 2010, 9:23pm UTC](https://www.ruby-forum.com/t/understanding-this-model-relationship-possibly-a-habtm-and-a-belongs-to/193096/4 "2010-08-11T21:23:37Z")
On Wed, Aug 11, 2010 at 2:26 PM, Marnen Laibow-Koser [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote: > Are these notice groups specific to the one user, or are they more like > global discussion topics? They are “created by one user” but multiple users can subscribe to them: “A User needs to be able to subscribe to multiple “notice groups” so that they could see the notices in the different groups they’re subscribed to.” > Can notice groups contain notices created by users other than the one > who created the group? No. > Sure. Just give the associations different names. Ok, I’ll look into that. thanks.