How would you model this? Thanks for any suggestions!

rubyonrails-talk
1

Hello,

maybe you can help me. I am looking for a reasonable way to model the following concept.

Assuming, we have 2 entities: 1. User (table users) 2. Town (table towns)

A user can, for example, add a town to the database, so we have 1:n relationship (one user can add several towns) and the corresponding foreign key in the town database, that's allright. But now, let's suppose, that a user can optional be a kind of contact person for one or more towns. What's the right way to realize this?

I thought about an attributed join table between users and towns. Since habtm doen not support attributes to be changed (as far as i know), we could realize it through has_many :through...

But now, I ask myself if that's the best way to model the relationship between users and towns and I really asked myself, how to name this join table. Normally, it's common practice to name tables after nouns, in this case maybe contact_persons. But I could it also name something like "acts_as_contact_person_for" to get a bit more straight forward. I really would like to have a good solution for this, because, I'll have a lot of such relations.

In conclusion: Do I generally have the right idea about that? How would you model this? And what's about the naming in this case? Is there a kind of pattern for this problem?

I really thank you a lot! :slight_smile:

Best wishes, ms

2

User can optional be a kind of contact person for one or more towns

Please explain this more detail.

3

Sounds good to me. Would do it the same way. The intermediate table name is always a nasty decision to make. I wouldn't use the acts_as variant, since that's used by plugins and could be confusing. I would go for either "users_towns" or "user_town_contacts" Most likely for the user_town_contacts variant, if there is any chance, that users and towns will in future get more kinds of relations.

4

I understand! Looking this:

User has many contacts Contacts has field town Then to find user contacts in town write User.contacts.find(:town => 'Yellow')' Why not?

5

you could model users polymorphic, such that users are either operators or contacts. then you would be able to say that a town belongs to a operator and has many contacts.

http://cheat.errtheblog.com/s/belongs_to/ http://cheat.errtheblog.com/s/has_many/

hope this helps