# Through Associations **URL:** \ **Category:** Rails\ **Created:** [July 26, 2007, 5:05pm UTC](https://www.ruby-forum.com/t/through-associations/110472 "2007-07-26T17:05:53Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Farhan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/b2d939/32.png) [@Farhan](https://www.ruby-forum.com/u/Farhan)\ **Post date:** [July 26, 2007, 5:05pm UTC](https://www.ruby-forum.com/t/through-associations/110472/1 "2007-07-26T17:05:53Z")
Hi, I’m a total noob to rails. I’m working my way through my first app and I desperately need help with through associations in rails. Task: get number of unread articles. Database structure: A. Users has\_many :activity has\_many :article, :through =\> :activity B. Activity belongs\_to :user belongs\_to :article C. Articles (user\_id,feed\_id,is\_read) has\_many :reading has\_many :user, :through =\> :reading belongs\_to :feed Any article that is in this table has been read and the “is\_read” field has been set to true. D. Feeds has\_many :article How do I go about getting the number of unread articles for a given user and feed? Any help will be greatly appreciated. Thanks in advance. Best, Farhan Sent from my iPhone ---
**Author:** ![Farhan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/b2d939/32.png) [@Farhan](https://www.ruby-forum.com/u/Farhan)\ **Post date:** [July 26, 2007, 6:35pm UTC](https://www.ruby-forum.com/t/through-associations/110472/2 "2007-07-26T18:35:01Z")
Farhan wrote: > Hi, > > I’m a total noob to rails. I’m working my way through my first app and > I desperately need help with through associations in rails. Through associations can be a bit complex for a beginner. Are you sure you don’t want to start with something simpler? Have you worked through the tutorial in AWDWR yet? > Task: get number of unread articles. > > Database structure: > A. Users > has\_many :activity > has\_many :article, :through =\> :activity Well, for starters, you should always use plurals with has\_many relationships. So, “has\_many :activities, has\_many :articles, :through =\> :activities”, etc. AWDWR would have taught you this, and many other fundamental concepts. > B. Activity > belongs\_to :user > belongs\_to :article good. But I’m not sure I understand the purpose of this model. What’s an “activity” as it relates to a user and an article? > C. Articles (user\_id,feed\_id,is\_read) > has\_many :reading > has\_many :user, :through =\> :reading > belongs\_to :feed Again, “:has\_many :readings” > Any article that is in this table has been read and the “is\_read” > field has been set to true. What table? Articles? I think you forgot to post a description of your “Reading” model. > D. Feeds > has\_many :article :articles > How do I go about getting the number of unread articles for a given > user and feed? Not sure I can really help here without a better understanding of the purpose of the Activity model and the structure of your Reading model. > Any help will be greatly appreciated. > > Thanks in advance. > > Best, > Farhan > – > [http://www.5valleys.com/](http://www.5valleys.com/) ---
**Author:** ![Farhan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/b2d939/32.png) [@Farhan](https://www.ruby-forum.com/u/Farhan)\ **Post date:** [July 26, 2007, 7:03pm UTC](https://www.ruby-forum.com/t/through-associations/110472/3 "2007-07-26T19:03:04Z")
Hi John, Thanks for replying. I’m will be getting the AWDWR book this evening. Okay; so I made the changes to pluralize the associations for has\_many. Thanks for the tip; makes the code more readable. I actually made a couple of typos in the “Database Structure”. I had changed the name of the “readings” to “activity” (now “activities”). The new database structure is as follows with the changes you requested: Database structure: A. Users has\_many :activities has\_many :articles, :through =\> :activities B. Activity (user\_id,feed\_id,is\_read) belongs\_to :user belongs\_to :article C. Articles has\_many :activities has\_many :users, :through =\> :activities belongs\_to :feed D. Feeds has\_many :articles The activity model will keep track of all read articles for the user. That is when a user reads an article it gets added to the “activities” table. This table has the user\_id, article\_id, and the is\_read columns. Any article that is added to the activity model has the is\_read column set to “true”. Hope this helps; otherwise let me know and I will provide more information. Thanks, Farhan ---
**Author:** ![Farhan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/b2d939/32.png) [@Farhan](https://www.ruby-forum.com/u/Farhan)\ **Post date:** [July 26, 2007, 8:01pm UTC](https://www.ruby-forum.com/t/through-associations/110472/4 "2007-07-26T20:01:10Z")
John, Thank you. I will try this two liner solution. Yes, in B the activity table has the “article\_id” and not “feed\_id”, sorry. Thank you for your patience, Farhan ---
**Author:** ![Farhan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/b2d939/32.png) [@Farhan](https://www.ruby-forum.com/u/Farhan)\ **Post date:** [July 26, 2007, 7:41pm UTC](https://www.ruby-forum.com/t/through-associations/110472/5 "2007-07-26T19:41:08Z")
insha wrote: > requested: > C. Articles > columns. Any article that is added to the activity model has the > is\_read column set to “true”. > > Hope this helps; otherwise let me know and I will provide more > information. > > Thanks, > Farhan Alright, first… at B. above, you say the activity table has a “feed\_id” column, but below you say it’s “article\_id”. I 'm going to plow forward with the second and ignore the first, since that what it should be. Ok, so now we want to get all the _read_ articles for a particular user. Add something like this to your User class. has\_many :readings, :class\_name =\> ‘Activity’, :conditions =\> ‘is\_read = 1’ has\_many :read\_articles, :through =\> :readings I hope that helps. – [http://www.5valleys.com/](http://www.5valleys.com/) ---
**Author:** ![Farhan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/b2d939/32.png) [@Farhan](https://www.ruby-forum.com/u/Farhan)\ **Post date:** [July 26, 2007, 10:09pm UTC](https://www.ruby-forum.com/t/through-associations/110472/6 "2007-07-26T22:09:24Z")
Here’s another scenario, since I’m getting confused: I have the following Models: A = User (name) B = Feed (name) C = Article (feed\_id, title) D = Reading (user\_id, article\_id, is\_read) What would be the simplest/easiest way to associate, using :through associations, these models so that I can easily do the following: 1. Get all articles that a user _has_ read 2. Get all articles that a user has _not_ read Best, Farhan