# Include with two references of one model of the same table **URL:** \ **Category:** Rails\ **Created:** [January 9, 2006, 10:18pm UTC](https://www.ruby-forum.com/t/include-with-two-references-of-one-model-of-the-same-table/51978 "2006-01-09T22:18:44Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![adambeazley](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/5f9b8f/32.png) [@adambeazley](https://www.ruby-forum.com/u/adambeazley)\ **Post date:** [January 9, 2006, 10:18pm UTC](https://www.ruby-forum.com/t/include-with-two-references-of-one-model-of-the-same-table/51978/1 "2006-01-09T22:18:44Z")
Hey guys, ``` I just came across this oddity, not sure what to make of it yet, but ``` I think it might be incorrect behavior. When doing a @inst.find(:all, :include =\> [“hometeam”, “awayteam”] …) hometeam and awayteam are two references from a belongs\_to that is of the same model and of the same table. I will get a pgerror stating that “matches”, which is the table that these fk’s loop back to is being ambiguously referenced. The SQL spit out showed only one select on “matches” where I think should be two selects on two aliases of “matches”. Heres some code below to better understand what I’m talking about. class Match \< ActiveRecord::Base belongs\_to :hometeam, :class\_name =\> “TeamsSeason”, :foreign\_key =\> “hometeam\_id” belongs\_to :awayteam, :class\_name =\> “TeamsSeason”, :foreign\_key =\> “awayteam\_id” end class TeamsSeason \< ActiveRecord::Base has\_many :hometeam, :class\_name =\> “Match”, :foreign\_key =\> “hometeam\_id”, :dependent =\> :destroy has\_many :awayteam, :class\_name =\> “Match”, :foreign\_key =\> “awayteam\_id”, :dependent =\> :destroy def self.find\_all\_played id find(:all, :include =\> [“hometeam”, “awayteam”]) end end Heres a sample of the error… |PGError: ERROR: table name “matches” specified more than once : SELECT matches.“awayteam\_goals” AS t2\_r1, matches.“season\_id” AS t1\_r7, teams\_seasons.“division\_id” AS t0\_r6, matches.“hometeam\_goals” AS t2\_r2, matches.“league\_id” AS t1\_r8, matches.“awayteam\_id” AS t2\_r3, matches.“venue\_id” AS t1\_r9, matches.“hometeam\_id” AS t2\_r4, matches.“matchtime\_start” AS t2\_r5, matches.“id” AS t1\_r0, matches.“matchtime\_stop” AS t2\_r6, matches.“awayteam\_goals” AS t1\_r1, teams\_seasons.“id” AS t0\_r0, matches.“season\_id” AS t2\_r7, matches.“hometeam\_goals” AS t1\_r2, teams\_seasons.“team\_id” AS t0\_r1, matches.“league\_id” AS t2\_r8, matches.“awayteam\_id” AS t1\_r3, teams\_seasons.“season\_id” AS t0\_r2, matches.“venue\_id” AS t2\_r9, matches.“division\_id” AS t1\_r10, matches.“hometeam\_id” AS t1\_r4, teams\_seasons.“coach\_id” AS t0\_r3, matches.“division\_id” AS t2\_r10, matches.“id” AS t2\_r0, matches.“played” AS t1\_r11, matches.“matchtime\_start” AS t1\_r5, teams\_seasons.“manager\_id” AS t0\_r4, matches.“played” AS t2\_r11, matches.“matchtime\_stop” AS t1\_r6, teams\_seasons.“league\_id” AS t0\_r5 FROM teams\_seasons LEFT OUTER JOIN matches ON matches.hometeam\_id = teams\_seasons.id LEFT OUTER JOIN matches ON matches.awayteam\_id = teams\_seasons.id WHERE (teams\_seasons.division\_id = 1) | I’d like to know if this is an incorrect implementation detail or just a _don’t\_do\_that_ problem =) ## – Adam B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Integrum Technologies, LLC Phone: +1 602 792 1270 Mobile: +1 480 580 7091 ---
**Author:** ![adambeazley](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/5f9b8f/32.png) [@adambeazley](https://www.ruby-forum.com/u/adambeazley)\ **Post date:** [January 28, 2006, 11:36pm UTC](https://www.ruby-forum.com/t/include-with-two-references-of-one-model-of-the-same-table/51978/2 "2006-01-28T23:36:57Z")
I am having the same probem… My code looks like this class Flight \< ActiveRecord::Base belongs\_to :airport\_of\_orgin, :class\_name =\> “Airport”, :foreign\_key =\> “orignal\_airport\_id” belongs\_to :airport\_of\_destine, :class\_name =\> “Airport”, :foreign\_key =\> “destination\_airport\_id” end Is there any method to solve is problem? regards, Leon. ---
**Author:** ![adambeazley](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/5f9b8f/32.png) [@adambeazley](https://www.ruby-forum.com/u/adambeazley)\ **Post date:** [January 29, 2006, 12:16am UTC](https://www.ruby-forum.com/t/include-with-two-references-of-one-model-of-the-same-table/51978/3 "2006-01-29T00:16:12Z")
Chad F. on irc suggest to use :joins to solve the problemm… using joins… look out for his book [http://www.pragmaticprogrammer.com/titles/fr\_rr/](http://www.pragmaticprogrammer.com/titles/fr_rr/) regards, Leon… ---
**Author:** ![adambeazley](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/5f9b8f/32.png) [@adambeazley](https://www.ruby-forum.com/u/adambeazley)\ **Post date:** [January 29, 2006, 2:13am UTC](https://www.ruby-forum.com/t/include-with-two-references-of-one-model-of-the-same-table/51978/4 "2006-01-29T02:13:37Z")
Yes, doing the joins manually is the best solution right now until AR figures out how to detect identical tables and alias them automatically. Bob S. [http://www.railtie.net/](http://www.railtie.net/) * * * From: removed\_email\_address@domain.invalid [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] On Behalf Of Leon L. Sent: Saturday, January 28, 2006 3:15 PM To: removed\_email\_address@domain.invalid Subject: Re: [Rails] Include with two references of one model of the same table Chad F. on irc suggest to use :joins to solve the problemm… using joins… look out for his book [http://www.pragmaticprogrammer.com/titles/fr\_rr/](http://www.pragmaticprogrammer.com/titles/fr_rr/) regards, Leon… On 1/28/06, Leon L. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: I am having the same probem… My code looks like this class Flight \< ActiveRecord::Base belongs\_to :airport\_of\_orgin, :class\_name =\> “Airport”, :foreign\_key =\> “orignal\_airport\_id” belongs\_to :airport\_of\_destine, :class\_name =\> “Airport”, :foreign\_key =\> “destination\_airport\_id” end Is there any method to solve is problem? regards, Leon. On 1/9/06, Adam B. \< removed\_email\_address@domain.invalid [mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) \> wrote: Hey guys, ``` I just came across this oddity, not sure what to make of it yet, but ``` I think it might be incorrect behavior. When doing a @inst.find(:all, :include =\> [“hometeam”, “awayteam”] …) hometeam and awayteam are two references from a belongs\_to that is of the same model and of the same table. I will get a pgerror stating that “matches”, which is the table that these fk’s loop back to is being ambiguously referenced. The SQL spit out showed only one select on “matches” where I think should be two selects on two aliases of “matches”. Heres some code below to better understand what I’m talking about. class Match \< ActiveRecord::Base belongs\_to :hometeam, :class\_name =\> “TeamsSeason”, :foreign\_key =\> “hometeam\_id” belongs\_to :awayteam, :class\_name =\> “TeamsSeason”, :foreign\_key =\> “awayteam\_id” end class TeamsSeason \< ActiveRecord::Base has\_many :hometeam, :class\_name =\> “Match”, :foreign\_key =\> “hometeam\_id”, :dependent =\> :destroy has\_many :awayteam, :class\_name =\> “Match”, :foreign\_key =\> “awayteam\_id”, :dependent =\> :destroy def self.find\_all\_played id find(:all, :include =\> [“hometeam”, “awayteam”]) end end Heres a sample of the error… |PGError: ERROR: table name “matches” specified more than once : SELECT matches.“awayteam\_goals” AS t2\_r1, matches.“season\_id” AS t1\_r7, teams\_seasons.“division\_id” AS t0\_r6, matches.“hometeam\_goals” AS t2\_r2, matches.“league\_id” AS t1\_r8, matches.“awayteam\_id” AS t2\_r3, matches.“venue\_id” AS t1\_r9, matches.“hometeam\_id” AS t2\_r4, matches.“matchtime\_start” AS t2\_r5, matches.“id” AS t1\_r0, matches.“matchtime\_stop” AS t2\_r6, matches.“awayteam\_goals” AS t1\_r1, teams\_seasons.“id” AS t0\_r0, matches.“season\_id” AS t2\_r7, matches.“hometeam\_goals” AS t1\_r2, teams\_seasons.“team\_id” AS t0\_r1, matches.“league\_id” AS t2\_r8, matches.“awayteam\_id” AS t1\_r3, teams\_seasons.“season\_id” AS t0\_r2, matches.“venue\_id” AS t2\_r9, matches.“division\_id” AS t1\_r10, matches.“hometeam\_id” AS t1\_r4, teams\_seasons.“coach\_id” AS t0\_r3, matches.“division\_id” AS t2\_r10, matches.“id” AS t2\_r0, matches.“played” AS t1\_r11, matches.“matchtime\_start” AS t1\_r5, teams\_seasons.“manager\_id” AS t0\_r4, matches.“played” AS t2\_r11, matches.“matchtime\_stop” AS t1\_r6, teams\_seasons.“league\_id” AS t0\_r5 FROM teams\_seasons LEFT OUTER JOIN matches ON matches.hometeam\_id = teams\_seasons.id LEFT OUTER JOIN matches ON matches.awayteam\_id = teams\_seasons.id WHERE (teams\_seasons.division\_id = 1) | I’d like to know if this is an incorrect implementation detail or just a _don’t\_do\_that_ problem =) ## – Adam B. \ Integrum Technologies, LLC Phone: +1 602 792 1270 Mobile: +1 480 580 7091 * * * Rails mailing list removed\_email\_address@domain.invalid [http://lists.rubyonrails.org/mailman/listinfo/rails](http://lists.rubyonrails.org/mailman/listinfo/rails) – First they laugh at you, then they ignore you, then they fight you. Then you win. – Mahatma Karamchand Gandhi