# Single Table Inheritance questions

**URL:** <https://www.ruby-forum.com/t/single-table-inheritance-questions/85333>\
**Category:** Rails\
**Created:** [February 12, 2007, 7:52pm UTC](https://www.ruby-forum.com/t/single-table-inheritance-questions/85333 "2007-02-12T19:52:51Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Lorin\_Rivers](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/cc9497/32.png) [@Lorin\_Rivers](https://www.ruby-forum.com/u/Lorin_Rivers)\
**Post date:** [February 12, 2007, 7:52pm UTC](https://www.ruby-forum.com/t/single-table-inheritance-questions/85333/1 "2007-02-12T19:52:51Z")

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I’m a rails noob and I’ve been playing around with creating an app  
that will display services provided at various schools.

At first, I had a schools table, then I decided that I wanted an  
agencies table as well. They share many attributes (address, etc) and  
differ only in a few (level, e.g., elementary, middle, etc). So I  
decided I would use organizations as my base. I have a “type” column.

I started by generating a scaffold: Organization Admin.

In my organization model, I added School \< Organization and Agency \<  
Organization.

That gives me generic organizations admin stuff, but there’s no “type”  
field in the new organization form.

I tried generating a scaffold for School Admin, but since there’s no  
table for schools, rails didn’t like that.

So if I want create a new school entry, how should I go about that?

Thanks!

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**Author:** ![Lorin\_Rivers](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/cc9497/32.png) [@Lorin\_Rivers](https://www.ruby-forum.com/u/Lorin_Rivers)\
**Post date:** [February 12, 2007, 8:22pm UTC](https://www.ruby-forum.com/t/single-table-inheritance-questions/85333/2 "2007-02-12T20:22:58Z")

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Hi,

I am fairly much a noob myself here but this is the way I have done it.

I did a script/generate controller for each of my subclasses and copied  
in  
the  
views to the corresponding directories. Then copy in all the methods  
from  
the base  
class controller to the subclass controllers. Edit all the references  
from  
Organisation to  
school in your School controller and that should do it.

Rails will handle the type column for you, you won’t have to set its  
value.

Hope that helps,

Keith

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**Author:** ![Lorin\_Rivers](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/cc9497/32.png) [@Lorin\_Rivers](https://www.ruby-forum.com/u/Lorin_Rivers)\
**Post date:** [February 12, 2007, 8:43pm UTC](https://www.ruby-forum.com/t/single-table-inheritance-questions/85333/3 "2007-02-12T20:43:01Z")

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Thanks, but I’m still not clear on how I would create a new school in  
my app. Right now, there’s a “new organization” link on the admin page  
(created by the scaffold command). What do I need to do to make a “new  
school” and “new agency” link (and have them do the right mojo with  
the “type” attribute).

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<div class="post-metadata">

**Author:** ![Lorin\_Rivers](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/cc9497/32.png) [@Lorin\_Rivers](https://www.ruby-forum.com/u/Lorin_Rivers)\
**Post date:** [February 12, 2007, 8:53pm UTC](https://www.ruby-forum.com/t/single-table-inheritance-questions/85333/4 "2007-02-12T20:53:05Z")

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Ok, it depends on how you are using scaffold. Do you have scaffold  
:organisation in your organisation  
controller or did you run script/generate scaffold organisation?

If you did the latter you probably have a folder under views called  
Organisations, if you create a school  
controller it will need a folder under views called schools. You will  
need a  
list, show, edit, new rhtml file  
for each function in that folder.

To create links between these you will need to add some navigation code  
to  
your layouts. You can either do this by  
creating a nav partial or by using the same layout for all three  
controllers  
and placing the nav in the layout. If you made a partial called  
\_nav.rhtml  
and placed it in views/shared you could call it from each layout file  
like  
so:  
\<%= render :partial =\> ‘shared/nav’ %\>

If you want to use the one layout with each controller you put a link in  
the  
controller like this,

layout ‘global’

where you have a layout file called global.rhtml in your views/layouts  
folder.

Keith

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<div class="post-metadata">

**Author:** ![Lorin\_Rivers](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/cc9497/32.png) [@Lorin\_Rivers](https://www.ruby-forum.com/u/Lorin_Rivers)\
**Post date:** [February 12, 2007, 11:44pm UTC](https://www.ruby-forum.com/t/single-table-inheritance-questions/85333/5 "2007-02-12T23:44:26Z")

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Your right and to be honest I’m not sure.

As I said I’m pretty much a noob myself with only about 6 weeks of  
Rails.

But this is what has worked for me.

Keith

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<div class="post-metadata">

**Author:** ![Lorin\_Rivers](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/cc9497/32.png) [@Lorin\_Rivers](https://www.ruby-forum.com/u/Lorin_Rivers)\
**Post date:** [February 12, 2007, 11:37pm UTC](https://www.ruby-forum.com/t/single-table-inheritance-questions/85333/6 "2007-02-12T23:37:26Z")

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Is it possible to do all this without duplicating everything. Doesn’t  
sound very DRYish…