# Why all columns of joined table get instantiated as String? **URL:** \ **Category:** Rails\ **Created:** [March 4, 2010, 3:58pm UTC](https://www.ruby-forum.com/t/why-all-columns-of-joined-table-get-instantiated-as-string/184563 "2010-03-04T15:58:54Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![oshanter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/2acd7d/32.png) [@oshanter](https://www.ruby-forum.com/u/oshanter)\ **Post date:** [March 4, 2010, 3:58pm UTC](https://www.ruby-forum.com/t/why-all-columns-of-joined-table-get-instantiated-as-string/184563/1 "2010-03-04T15:58:54Z")
Been developing in Rails for about a month and I’m still working on grasping its subtleties. Can someone please shed some light on this simple scenario? ## Schema create\_table :books do |t| t.string :title t.integer :year end create\_table :pages do |t| t.integer :no t.references :book end ## Models Book has\_many :pages Page belongs\_to :book Then in Rails’ console: @pages = Page.all( :select =\> ‘pages.id, pages.no, books.year book\_year’, :joins =\> :book ) @pages.first.no.class #=\> Fixnum @pages.first.book\_year.class #=\> String What I don’t understand is why book\_year is a String instead of a Fixnum. Is it possible to get Book’s columns correctly instantiated? Thanks ---
**Author:** ![oshanter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/2acd7d/32.png) [@oshanter](https://www.ruby-forum.com/u/oshanter)\ **Post date:** [March 4, 2010, 5:41pm UTC](https://www.ruby-forum.com/t/why-all-columns-of-joined-table-get-instantiated-as-string/184563/2 "2010-03-04T17:41:04Z")
On Mar 4, 2:58 pm, Jack S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > What I don’t understand is why book\_year is a String instead of a > Fixnum. Is it possible to get Book’s columns correctly instantiated? Not that I know of. The typecasting stuff only knows about the columns of the model itself. Fred ---
**Author:** ![oshanter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/2acd7d/32.png) [@oshanter](https://www.ruby-forum.com/u/oshanter)\ **Post date:** [March 5, 2010, 3:07pm UTC](https://www.ruby-forum.com/t/why-all-columns-of-joined-table-get-instantiated-as-string/184563/3 "2010-03-05T15:07:00Z")
Thanks, Fred. I suppose I’ll stick with views and conversions. ---
**Author:** ![oshanter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/2acd7d/32.png) [@oshanter](https://www.ruby-forum.com/u/oshanter)\ **Post date:** [March 5, 2010, 7:17pm UTC](https://www.ruby-forum.com/t/why-all-columns-of-joined-table-get-instantiated-as-string/184563/4 "2010-03-05T19:17:11Z")
On Fri, Mar 5, 2010 at 9:07 AM, Jack S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Thanks, Fred. I suppose I’ll stick with views and conversions. Why not pages = Page.all(:include =\> :book) pages.first.book.year – Rick DeNatale Blog: [http://talklikeaduck.denhaven2.com/](http://talklikeaduck.denhaven2.com/) Twitter: [http://twitter.com/RickDeNatale](http://twitter.com/RickDeNatale) WWR: [http://www.workingwithrails.com/person/9021-rick-denatale](http://www.workingwithrails.com/person/9021-rick-denatale) LinkedIn: [http://www.linkedin.com/in/rickdenatale](http://www.linkedin.com/in/rickdenatale) ---
**Author:** ![oshanter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/2acd7d/32.png) [@oshanter](https://www.ruby-forum.com/u/oshanter)\ **Post date:** [March 6, 2010, 2:01am UTC](https://www.ruby-forum.com/t/why-all-columns-of-joined-table-get-instantiated-as-string/184563/5 "2010-03-06T02:01:37Z")
On Fri, Mar 5, 2010 at 2:12 PM, Jack S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > :conditions =\> “books.library\_id = #{1}” > ) > > AR will generate: > SELECT pages.id, pages.no FROM “pages” INNER JOIN “books” ON “books”.id > = “pages”.book\_id WHERE (books.library\_id = 1) > > So the join has already been done. Wouldn’t :include make a redundant > query? Then just change the joins to include: Page.all( :include =\> :book, :conditions =\> [“books.library\_id = ?”, 1] ) ## Which will both allow you to refer to the books fields in the where clause, and return an collection of object graphs rather than page object corrupted with fields they shouldn’t have. Rick DeNatale Blog: [http://talklikeaduck.denhaven2.com/](http://talklikeaduck.denhaven2.com/) Twitter: [http://twitter.com/RickDeNatale](http://twitter.com/RickDeNatale) WWR: [http://www.workingwithrails.com/person/9021-rick-denatale](http://www.workingwithrails.com/person/9021-rick-denatale) LinkedIn: [http://www.linkedin.com/in/rickdenatale](http://www.linkedin.com/in/rickdenatale) ---
**Author:** ![oshanter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/2acd7d/32.png) [@oshanter](https://www.ruby-forum.com/u/oshanter)\ **Post date:** [March 6, 2010, 6:49pm UTC](https://www.ruby-forum.com/t/why-all-columns-of-joined-table-get-instantiated-as-string/184563/6 "2010-03-06T18:49:54Z")
Rick Denatale wrote: > Then just change the joins to include: > > Page.all( > :include =\> :book, > :conditions =\> [“books.library\_id = ?”, 1] > ) > > Which will both allow you to refer to the books fields in the where > clause, and return an collection of object graphs rather than page > object corrupted with fields they shouldn’t have. That’s true, but I lose control over :select Page.all( :select =\> ‘pages.id, pages.no’, :include =\> :book, :conditions =\> [“books.library\_id = ?”, 1] ) …will generate: SELECT “pages”.“id” AS t0\_r0, “pages”.“no” AS t0\_r1, “pages”.“book\_id” AS t0\_r2, “pages”.“created\_at” AS t0\_r3, “pages”.“updated\_at” AS t0\_r4, “books”.“id” AS t1\_r0, “books”.“title” AS t1\_r1, “books”.“year” AS t1\_r2, “books”.“library\_id” AS t1\_r3, “books”.“created\_at” AS t1\_r4, “books”.“updated\_at” AS t1\_r5 FROM “pages” LEFT OUTER JOIN “books” ON “books”.id = “pages”.book\_id WHERE (books.library\_id = 1) The real “books” and “pages” have decimal and large text columns that are not always needed. ---
**Author:** ![oshanter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/2acd7d/32.png) [@oshanter](https://www.ruby-forum.com/u/oshanter)\ **Post date:** [March 6, 2010, 8:48pm UTC](https://www.ruby-forum.com/t/why-all-columns-of-joined-table-get-instantiated-as-string/184563/7 "2010-03-06T20:48:17Z")
On 6 March 2010 17:49, Jack S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > The real “books” and “pages” have decimal and large text columns that > are not always needed. Could be worth considering extracting those fields into another table and have a 1:1 link… a little messy, but saves you returning lots of data when you only need a small part of it. ---
**Author:** ![oshanter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/2acd7d/32.png) [@oshanter](https://www.ruby-forum.com/u/oshanter)\ **Post date:** [March 5, 2010, 8:12pm UTC](https://www.ruby-forum.com/t/why-all-columns-of-joined-table-get-instantiated-as-string/184563/8 "2010-03-05T20:12:34Z")
Rick Denatale wrote: > Why not > > pages = Page.all(:include =\> :book) I usually need to filter by, let’s say, a certain library: @pages = Page.all( :select =\> ‘pages.id, pages.no’, :joins =\> :book, :conditions =\> “books.library\_id = #{1}” ) AR will generate: SELECT pages.id, pages.no FROM “pages” INNER JOIN “books” ON “books”.id = “pages”.book\_id WHERE (books.library\_id = 1) So the join has already been done. Wouldn’t :include make a redundant query?