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View Code? Open in Web Editor NEWA gem for using Multiple Table Inheritance with rails 3
A gem for using Multiple Table Inheritance with rails 3
== Welcome to Rails Rails is a web-application framework that includes everything needed to create database-backed web applications according to the Model-View-Control pattern. This pattern splits the view (also called the presentation) into "dumb" templates that are primarily responsible for inserting pre-built data in between HTML tags. The model contains the "smart" domain objects (such as Account, Product, Person, Post) that holds all the business logic and knows how to persist themselves to a database. The controller handles the incoming requests (such as Save New Account, Update Product, Show Post) by manipulating the model and directing data to the view. In Rails, the model is handled by what's called an object-relational mapping layer entitled Active Record. This layer allows you to present the data from database rows as objects and embellish these data objects with business logic methods. You can read more about Active Record in link:files/vendor/rails/activerecord/README.html. The controller and view are handled by the Action Pack, which handles both layers by its two parts: Action View and Action Controller. These two layers are bundled in a single package due to their heavy interdependence. This is unlike the relationship between the Active Record and Action Pack that is much more separate. Each of these packages can be used independently outside of Rails. You can read more about Action Pack in link:files/vendor/rails/actionpack/README.html. == Getting Started 1. At the command prompt, create a new Rails application: <tt>rails new myapp</tt> (where <tt>myapp</tt> is the application name) 2. Change directory to <tt>myapp</tt> and start the web server: <tt>cd myapp; rails server</tt> (run with --help for options) 3. Go to http://localhost:3000/ and you'll see: "Welcome aboard: You're riding Ruby on Rails!" 4. Follow the guidelines to start developing your application. You can find the following resources handy: * The Getting Started Guide: http://guides.rubyonrails.org/getting_started.html * Ruby on Rails Tutorial Book: http://www.railstutorial.org/ == Debugging Rails Sometimes your application goes wrong. Fortunately there are a lot of tools that will help you debug it and get it back on the rails. First area to check is the application log files. Have "tail -f" commands running on the server.log and development.log. Rails will automatically display debugging and runtime information to these files. Debugging info will also be shown in the browser on requests from 127.0.0.1. You can also log your own messages directly into the log file from your code using the Ruby logger class from inside your controllers. Example: class WeblogController < ActionController::Base def destroy @weblog = Weblog.find(params[:id]) @weblog.destroy logger.info("#{Time.now} Destroyed Weblog ID ##{@weblog.id}!") end end The result will be a message in your log file along the lines of: Mon Oct 08 14:22:29 +1000 2007 Destroyed Weblog ID #1! More information on how to use the logger is at http://www.ruby-doc.org/core/ Also, Ruby documentation can be found at http://www.ruby-lang.org/. There are several books available online as well: * Programming Ruby: http://www.ruby-doc.org/docs/ProgrammingRuby/ (Pickaxe) * Learn to Program: http://pine.fm/LearnToProgram/ (a beginners guide) These two books will bring you up to speed on the Ruby language and also on programming in general. == Debugger Debugger support is available through the debugger command when you start your Mongrel or WEBrick server with --debugger. This means that you can break out of execution at any point in the code, investigate and change the model, and then, resume execution! You need to install ruby-debug to run the server in debugging mode. With gems, use <tt>sudo gem install ruby-debug</tt>. Example: class WeblogController < ActionController::Base def index @posts = Post.all debugger end end So the controller will accept the action, run the first line, then present you with a IRB prompt in the server window. Here you can do things like: >> @posts.inspect => "[#<Post:0x14a6be8 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}>, #<Post:0x14a6620 @attributes={"title"=>"Rails", "body"=>"Only ten..", "id"=>"2"}>]" >> @posts.first.title = "hello from a debugger" => "hello from a debugger" ...and even better, you can examine how your runtime objects actually work: >> f = @posts.first => #<Post:0x13630c4 @attributes={"title"=>nil, "body"=>nil, "id"=>"1"}> >> f. Display all 152 possibilities? (y or n) Finally, when you're ready to resume execution, you can enter "cont". == Console The console is a Ruby shell, which allows you to interact with your application's domain model. Here you'll have all parts of the application configured, just like it is when the application is running. You can inspect domain models, change values, and save to the database. Starting the script without arguments will launch it in the development environment. To start the console, run <tt>rails console</tt> from the application directory. Options: * Passing the <tt>-s, --sandbox</tt> argument will rollback any modifications made to the database. * Passing an environment name as an argument will load the corresponding environment. Example: <tt>rails console production</tt>. To reload your controllers and models after launching the console run <tt>reload!</tt> More information about irb can be found at: link:http://www.rubycentral.org/pickaxe/irb.html == dbconsole You can go to the command line of your database directly through <tt>rails dbconsole</tt>. You would be connected to the database with the credentials defined in database.yml. Starting the script without arguments will connect you to the development database. Passing an argument will connect you to a different database, like <tt>rails dbconsole production</tt>. Currently works for MySQL, PostgreSQL and SQLite 3. == Description of Contents The default directory structure of a generated Ruby on Rails application: |-- app | |-- assets | |-- images | |-- javascripts | `-- stylesheets | |-- controllers | |-- helpers | |-- mailers | |-- models | `-- views | `-- layouts |-- config | |-- environments | |-- initializers | `-- locales |-- db |-- doc |-- lib | `-- tasks |-- log |-- public |-- script |-- test | |-- fixtures | |-- functional | |-- integration | |-- performance | `-- unit |-- tmp | |-- cache | |-- pids | |-- sessions | `-- sockets `-- vendor |-- assets `-- stylesheets `-- plugins app Holds all the code that's specific to this particular application. app/assets Contains subdirectories for images, stylesheets, and JavaScript files. app/controllers Holds controllers that should be named like weblogs_controller.rb for automated URL mapping. All controllers should descend from ApplicationController which itself descends from ActionController::Base. app/models Holds models that should be named like post.rb. Models descend from ActiveRecord::Base by default. app/views Holds the template files for the view that should be named like weblogs/index.html.erb for the WeblogsController#index action. All views use eRuby syntax by default. app/views/layouts Holds the template files for layouts to be used with views. This models the common header/footer method of wrapping views. In your views, define a layout using the <tt>layout :default</tt> and create a file named default.html.erb. Inside default.html.erb, call <% yield %> to render the view using this layout. app/helpers Holds view helpers that should be named like weblogs_helper.rb. These are generated for you automatically when using generators for controllers. Helpers can be used to wrap functionality for your views into methods. config Configuration files for the Rails environment, the routing map, the database, and other dependencies. db Contains the database schema in schema.rb. db/migrate contains all the sequence of Migrations for your schema. doc This directory is where your application documentation will be stored when generated using <tt>rake doc:app</tt> lib Application specific libraries. Basically, any kind of custom code that doesn't belong under controllers, models, or helpers. This directory is in the load path. public The directory available for the web server. Also contains the dispatchers and the default HTML files. This should be set as the DOCUMENT_ROOT of your web server. script Helper scripts for automation and generation. test Unit and functional tests along with fixtures. When using the rails generate command, template test files will be generated for you and placed in this directory. vendor External libraries that the application depends on. Also includes the plugins subdirectory. If the app has frozen rails, those gems also go here, under vendor/rails/. This directory is in the load path.
Just trying to order by a predecessor column. Is there an easy way to do this? cause I keep getting the "no such column" error.
Thanks!
Just downloaded the gem and made some test on the console.
I get an error when I try to get values of attributes of the parent table (posts).
I launch the following command: @posts = BlogPost.where("posts.title = 'test'") and here is the error message I get:
ERROR: missing FROM-clause entry for table "posts"
LINE 1: SELECT "blog_posts".* FROM "blog_posts" WHERE (posts.title ...
Is that a known issue?
It's a perfomance issue.
It sends cyclic update request on model update,
I have Product model as a predecessor and Movie as a heir.
When I update movie it sends 4 request to DB instead of 2.
Here is a simple example to reproduce:
mov.name = 'a_new_name'
mov.save
(0.2ms) UPDATE "products" SET "name" = 'one', "updated_at" = '2011-09-01 14:17:55.933125' WHERE "products"."id" = 2
SQL (0.1ms) UPDATE "movies" SET "updated_at" = '2011-09-01 14:17:55.934588' WHERE "movies"."id" = 2
SQL (0.0ms) UPDATE "products" SET "updated_at" = '2011-09-01 14:17:55.935150' WHERE "products"."id" = 2
SQL (0.0ms) UPDATE "movies" SET "updated_at" = '2011-09-01 14:17:55.935528' WHERE "movies"."id" = 2
Environment:
DB: SQLIte3
Rails: 3.1
Hi,
and thank for your gem. I've 2 classes : Media (predecessor) and Image(heir). I'm trying to destroy a media's instance (destroy) through the Image.destroy method.
Actually, the "predecessor" class is destroyed by "heir".destroy but the reciprocal isn't working.
Could you indicate me how could I fix this issue ?
Thx
Hello,
First, thank you for this tool which is very easy to use.
I met a problem with 'Resque' and 'Heritage' -> https://github.com/defunkt/resque
I have a class SoapMonitor which inherites Monitor.
require 'snmp'
class SoapMonitor < ActiveRecord::Base
attr_accessible :name, :description, :host, :port, :wsdl_filename
acts_as_heir_of :monitor
validates_presence_of :name, :host
end
A class with a perform method ( Job that worker have to execute)
require 'resque'
require 'soapmonitor'
class Update_SoapMonitor
@queue = :SoapMonitor_queue
def self.perform(webio_id)
ActiveRecord::Base.verify_active_connections!
soapm = SoapMonitor.find(webio_id)
puts soapm.wsdl_filename #This is OK (Attribute from SoapMonitor)
puts soapm.host #This is not OK (Attribute from Monitor)
end
end
soapm.host returns me :
Class
Update_SoapMonitor
Arguments
"1"
Exception
SystemStackError
Error
stack level too deep
/usr/lib/ruby/gems/1.8/gems/heritage-0.3.1/lib/heritage/active_record/acts_as_heir.rb:57:in `predecessor_without_build'
/usr/lib/ruby/gems/1.8/gems/heritage-0.3.1/lib/heritage/active_record/acts_as_heir.rb:58:in `predecessor'
/usr/lib/ruby/gems/1.8/gems/heritage-0.3.1/lib/heritage/active_record/acts_as_heir.rb:20:in `host'
/usr/lib/ruby/gems/1.8/gems/savon-0.9.9/lib/savon/client.rb:165:in `send'
/usr/lib/ruby/gems/1.8/gems/savon-0.9.9/lib/savon/client.rb:165:in `method_missing'
/var/www/html/MyApp/app/models/soapMonitor.rb:32:in `create_soap_client'
/usr/lib/ruby/gems/1.8/gems/savon-0.9.9/lib/savon/client.rb:159:in `instance_eval'
/usr/lib/ruby/gems/1.8/gems/savon-0.9.9/lib/savon/client.rb:159:in `evaluate'
/usr/lib/ruby/gems/1.8/gems/savon-0.9.9/lib/savon/client.rb:147:in `process'
/usr/lib/ruby/gems/1.8/gems/savon-0.9.9/lib/savon/client.rb:34:in `initialize'
/var/www/html/MyApp/app/models/soapMonitor.rb:31:in `new'
/var/www/html/MyApp/app/models/soapMonitor.rb:31:in `create_soap_client'
/var/www/html/MyApp/app/models/soapMonitor.rb:80:in `get_value'
/var/www/html/MyApp/app/models/soapMonitor.rb:41:in `version'
/var/www/html/MyApp/app/workers/Update_SoapMonitor.rb:28:in `perform'
Do you have any suggestions to help me ?
Bests Regards,
I'm able to create child objects without satisfying the validation on the parent object.
When I try to create the parent object directly without the required field, I get the validation error like I'm supposed to. However, no complaints when I create the child object without the required parent field set.
NameError: uninitialized constant Heritage::ActiveRecord::ActsAsHeir::Post
Hi,
Thanks for the great gem.
I couldn't figure out how to implement associations when the type of the heir is unknown.
Example: I want to do something like:
class Post < ActiveRecord::Base
acts_as_predecessor
belongs_to :site
end
class BlogPost < ActiveRecord::Base
acts_as_heir_of :post
end
class ImagePost < ActiveRecord::Base
acts_as_heir_of :post
end
class Site < ActiveRecord::Base
has_many :posts #could be BlogPost or ImagePost
def create_some_posts
post1 = BlogPost.create
posts << post1
post2 = ImagePost.create
posts << post2
end
end
How should I fix this code? Please advise. Thanks!
Hi,
When i try use your software to inherit my im_image table from im_file model, i received the following error
Expected /Users/hsobral/sistemas/imager/app/models/im_file.rb to define Im_file
I founded this two lines using capitalize. I think the right would be to use the camelize
self._predecessor_klass = Object.const_get(predecessor_symbol.to_s.capitalize)
...
has_one :predecessor, :as => :heir, :class_name => predecessor_symbol.to_s.camelize, :autosave => true, :dependent => :destroy
Thanks.
Henrique
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