How can I create activerecord models that are subsets of a certain model?

Posted by gsiener on Stack Overflow See other posts from Stack Overflow or by gsiener
Published on 2010-05-14T01:32:19Z Indexed on 2010/05/14 4:54 UTC
Read the original article Hit count: 222

Filed under:

activerecord

|

inheritance

|

ruby-on-rails

I've seen this before but can't figure out what the correct term is. Basically, I'd like to create models for a specific subset of table data. E.g. (these are not the real classes)

class Person < ActiveRecord::Base

class Man < Person
  <something here> :gender => 'male'

© Stack Overflow or respective owner

Related posts about activerecord

Rails & ActiveRecord: Appending methods to models that inherit from ActiveRecord::Base

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a standard ActiveRecord model with the following: class MyModel < ActiveRecord::Base custom_method :first_field, :second_field end At the moment, that custom_method is picked up by a module sent to ActiveRecord::Base. The functionality basically works, but of course, it attaches itself… >>> More
Rails ActiveRecord - Best way to perform an include?

as seen on Stack Overflow - Search for 'Stack Overflow'
I have three models: class Book < ActiveRecord::Base has_many :collections has_many :users, :through => :collections end class User < ActiveRecord::Base has_many :collections has_many :books, :through => :collections end class Collection < ActiveRecord::Base belongs_to… >>> More
Getting types of the attributes in an ActiveRecord object

as seen on Stack Overflow - Search for 'Stack Overflow'
I would like to know if it is possible to get the types (as known by AR - eg in the migration script and database) programmatically (I know the data exists in there somewhere). For example, I can deal with all the attribute names: ar.attribute_names.each { |name| puts name } .attributes just… >>> More
Changing ActiveRecord attribute value in before_save hook

as seen on Stack Overflow - Search for 'Stack Overflow'
I needed to fix the encoding of an ActiveRecord attribute and decided to do it in a before_save hook. And at this point I noticed an unexpected feature. When I wanted to change the value of the attribute, simple using the attribute_name=XY did not work as I expected. Instead of that I needed to use… >>> More
Conditions with whitespaces in activerecord find

as seen on Stack Overflow - Search for 'Stack Overflow'
So i am trying to do this Order.find :all, :conditions => "org = 'test org'" what ends up firing is SELECT * FROM `orders` WHERE (org = 'test org') the whitespace in the argument gets stripped. what am i missing.. im really stumped here. please help! >>> More

Related posts about inheritance

Single Table Inheritance (Database Inheritance design options) pros and cons and in which case it us

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I study about today about 2 database design inheritance approaches: 1. Single Table Inheritance 2. Class Table Inheritance In my student opinion Single Table Inheritance make database more smaller vs other approaches because she use only 1 table. But i read that the more favorite approach… >>> More
How to use Private Inheritence aka C++ in C# and Why not it is present in C#

as seen on Stack Overflow - Search for 'Stack Overflow'
I know that private inheritance is supported in C++ and only public inheritance is supported in C#. I also came across an article which says that private inheritance usually defines a HAS-A relationship and kind of an aggregation relationship between the classes. EDIT: C++ code for private inheritance: The… >>> More
[PHP] Singleton class and using inheritance

as seen on Stack Overflow - Search for 'Stack Overflow'
I have am working on a web application that makes use of helper classes. These classes hold functions to various operation such as form handling. Sometimes I need these classes at more than one spot in my application, The way I do it now is to make a new Object. I can't pass the variable, this will… >>> More
Difference between Inheritance and Composition

as seen on Stack Overflow - Search for 'Stack Overflow'
Are Composition and Inheritance are the same? If I want to implement the composition pattern, how can I do that in Java? >>> More
C# Interface Inheritance (Basics)

as seen on Stack Overflow - Search for 'Stack Overflow'
Why does the following produce a compiler error: public interface OwnSession : ISession { } [...] OwnSession s = SessionFactory.OpenSession(); // compiler error (in german unfortunately) [...] "SessionFactory" returns a "ISession" on "OpenSession()" (NHibernate) >>> More