Ok, I was poking around github's rails activemodel stuff for the heck of it.
Link: https://github.com/rails/rails/tree/master/activemodel
When I saw this code included in their README.rdoc
class Person
include ActiveModel::AttributeMethods
attribute_method_prefix 'clear_'
define_attribute_methods :name, :age
attr_accessor :name, :age
def clear_attribute(attr)
send("#{attr}=", nil)
end
end
person = Person.new
person.clear_name
person.clear_age
Thought that above code was pretty cool as I wasn't familiar with this. Only have seen something like this with dynamic find method, sort of.
So wanted to run it, but I don't know how to run it outside of the context of ROR framework.
How do I go about doing that?
Thanks.
If this question is dumb, let me know? (nicely, please).
Asking because I've heard that people run ORM outside of ROR framework, so, that's why I'm asking this question in the first place. Let me know if I misunderstood this.
You could always run it in an IRB as it's a ruby method not specific to Rails.
http://ruby-doc.org/core-2.1.1/Object.html#method-i-sendirb
For doing Active Record Like Models you could use this gem http://rubygems.org/gems/activemodel, or this gem https://github.com/solnic/virtus.
First create one dummy application in Rails,then open rails console using this command rails c and you past the code then you could verify.
or
Inside application lib directory create one file with .rb extension now open console and you can verify.
More info click here
Related
I'm new to Ruby on Rails and I'm looking at an application that has a variable called current_teacher. I cannot seem to find where this is set. Everywhere I look the code seems to read from it but where is it set. Is this one of those things that Rails does for you. There is a mode and a table called teachers, so I'm sure this has something to do with it.
I'm very confused by statements like the following, can someone tell me how Rails does this?
if current_teacher.can_request_fieldtrip
Suppose you have a controller like :
class ClientsController < ApplicationController
def new
if current_teacher.can_request_fieldtrip
# code
end
end
end
Here is debugging tips :
(a) put this in your Gemfile and do bundle install :
`gem 'pry-rails', :group => :development`
(b) Put the line binding.pry just before the if statement.
(c) Start rails server using rails s.
(d) Hit the browser like http://localhost:3000/new
(e) Now you will be in the Pry console. Just do in the console,
method(:current_teacher).source_location
And the above line tell you where the method has been defined.
Documentation of Method#source_location
Returns the Ruby source filename and line number containing this method or nil if this method was not defined in Ruby (i.e. native)
Rails does not support authentication by itself, however there are a lot of 'add-ons' that rails can use. These 'add-ons' are called gems. This can be a little confusing because you can't actually see their code inside your project folder.
If you open a file called "Gemfile" (it should be in your project folder) you can see a list of gems that you use. Try searching their names on google, you will probably find official web page that contains it's documentation. That way can learn what they do and how to use them.
current_teacher method smells like "Devise" gem
https://github.com/plataformatec/devise
I'm not sure about can_request_fieldtrip, this could be a custom method defined in Teacher model.
I have already read The Basics Of Creating Rails Plugins and several other articles, but I can't find how to supply a model with a gem.
Say, I want to make a gem for tagging (yes, I know about acts_as_taggable_on gem, I need different functionality). So, I want the model Tag to be bundled in the gem. I found no tutorial explaining that.
Of course I tried to reverse-engineer acts_as_taggable_on gem to understand how does it work, but it brought even more confusion: the tutorial I mentioned above says that I should have a dummy app in my gem, in order to test the gem. BUT, acts_as_taggable_on has no such dummy application! How how does it get tested, then?
About the model: ok, I see the file lib/acts_as_taggable_on/tag.rb that seems to be a Tag model:
module ActsAsTaggableOn
class Tag < ::ActiveRecord::Base
# ..........................
end
end
I see that file lib/acts-as-taggable-on.rb requires tag:
require "acts_as_taggable_on/tag"
So I've applied the same approach (assume my plugin is named dftags) :
I have added file lib/dftags/tag.rb:
module Dftags
class Tag < ::ActiveRecord::Base
# attr_accessible :title, :body
end
end
And my lib/dftags.rb looks like this:
module Dftags
end
require "dftags/tag"
I have specs tag_spec.rb:
require 'spec_helper'
describe Tag do
let(:tag) { Tag.new(name: "") }
it { should validate_presence_of :name }
end
And when I run bundle exec rspec spec/, I got error unitialized constant Tag (NameError).
It seems I missed something important. Plus, again, I have dummy app for testing, but acts_as_taggable_on doesn't; so, the testing approach should be different..
So, the questions:
How can I supply a model with gem?
How can I test my gem without dummy app?
Are there some advanced docs about writing rails gems? Actually I tried to check out one more famous gem: devise, but the ruby-fu and rails-fu of the authors is too strong for me to understand it. Where do people learn all of it?
How can I test my gem without dummy app?
The dummy app is only a helper that allows you to use your normal rails testing workflow when building a gem / plugin. You could run the tests without a dummy app but you would need a lot more manual work.
acts_as_taggable_on is pretty much active_record only with the exception of a single helper (as far as I can tell from a quick glance). The author therefore decided that the overhead of maintaining the dummy app was not worth the effort and is setting up active_record by hand. See here https://github.com/mbleigh/acts-as-taggable-on/blob/master/spec/spec_helper.rb#L24 how he establishes the connection to the database.
This code would not be necessary when using a dummy app as rails is taking care of it.
The same is true for the helper. Instead of using the test methods provided by rails he creates a new Class that includes the helper and uses an instance of this class to test it (h/acts-as-taggable-on/blob/master/spec/acts_as_taggable_on/tags_helper_spec.rb#L11).
I have a Rails app that uses a gem called ActsAsTaggableOnSteroids, which is a Rails Engine. Specifically, I'm using PavelNartov's fork of the gem. But nevermind that.
I need to add specific functionality to the Tag model, which is supplied by the engine.
But, according to my understanding of Rails engines and the magical loading functionality in Rails, if I put a file called "tag.rb" in my models directory, then it will completely replace the one from the Engine.
Ideally, I would be able to do something like:
class Tag < ActsAsTaggable::Tag
# my stuff
end
...but alas, that doesn't work because the model supplied by the engine is not namespaced.
So, I came up with this nightmare, which I put in app/models/tag.rb:
path = ActsAsTaggable::Engine.config.eager_load_paths.grep(/models/).first
require File.join(path, 'tag')
Tag.class_eval { include TagConcern }
But there has to be a better way! I feel like I'm missing something. I'd prefer not to add this strangeness to my app if possible.
Just require the file by looking up the path of the gem's model:
require File.join(Gem::Specification.find_by_name("bborn-acts_as_taggable_on_steroids").gem_dir, 'app/models/tag')
Tag.class_eval do
# ...
end
I'm using the Rails gem SimpleForm, but I think my question may be applicable to any gem.
https://github.com/plataformatec/simple_form
It has a lot of great features and customization, but I'm looking to go a bit further. For example, I really wish the markup generated had no default classes inserted into it, but I'd still like the ability to insert my own manually. I found that I could remove some of the classes by commenting out lines in the gem files. However this is outside of my project-- I would want a DRY solution that will stay with my project when I deploy to production, preferably without having to pack all of my gems.
I imagine this is a common situation that could apply to any gem, and I should be able to override any gem wholly or partially probably by adding customs files in my project that override the gem... but I'm not sure how.
Any help would be appreciated! Thanks.
Are you talking about monkey patching? Say your gem has a class in a file
# simple_form_gem/lib/some_file.rb
class A
def some_method
puts 'A'
end
end
If you want to change the output of #some_method then you can create an initializer file and do
# config/initializers/my_monkey_patch_for_simple_form_gem.rb
class A
def some_method
puts 'duck punching'
end
end
Your monkey patch will only affect A#some_method, and not other methods in A. Just make sure the output of your monkey patch won't break something else in the gem.
I'm messing around with rails 2.3 templates and want to be able to use the app name as a variable inside my template, so when I use...
rails appname -m path/to/template.rb
...I want to be able to access appname inside template.rb. Anyone know how to do this?
Thanks
I was looking for an answer to this question. unfortunately the answer above (#root) doesn't seem to work in Rails 3.
Here's the variables you can access in Rails 3 app templates (even easier):
#app_name
#app_path
Thanks for the answers. Mike Woodhouse, you were so close. Turns out, all you need to do to access the appname from inside your rails template is...
#root.split('/').last
The #root variable is the first thing created when initializing templates and is available inside your rails templates. RAILS_ROOT does not work.
In Rails 3, use the app_name attribute.
See the documentation for the Rails::Generators::AppGenerator.
I ran into a similar problem, none of the variables listed above were available to me in Rails 4. I found that #name was available while running
rails plugin new engines/dummy -m my_template.rb
There are other useful variables available from within the template. You can see for yourself and play around by utilizing pry. Inside my template I added
require 'pry'; binding.pry
and then ran ls to show a list of available instance variables
ls -i
instance variables:
#_initializer #app_path #behavior #destination_stack #extra_entries #name #output_buffer #shell
#_invocations #args #builder #dummy_path #gem_filter #options #rails_template #source_paths
#after_bundle_callbacks #author #camelized #email #in_group #original_name #shebang
There's probably a more straightforward way, but this seems to work:
RAILS_ROOT.split('/').last
EDIT: Bleah - this got voted down once, and the voter was right. If I'd read the question more carefully, I'd have noticed the 2.3 and template.rb elements. Apologies.
I suspect that RAILS_ROOT won't have been created at the point that you need the app name. Looking at ruby\lib\ruby\gems\1.8\gems\rails-2.2.2\bin\rails, however, almost the first thing that happens is this:
app_path = ARGV.first
It's used at the end of the script to allow a chdir and freeze to be done if needed - I didn't know I could insta-freeze at creation, so I learned something new at least. ARGV then gets used here:
Rails::Generator::Scripts::Generate.new.run(ARGV, :generator => 'app')
which quickly gets us to the place where ARGV is really handled:
rails-2.3.1\lib\rails_generator\scripts.rb
where I see
Rails::Generator::Base.instance(options[:generator], args, options).command(options[:command]).invoke!
Somewhere below here is probably where the templating gets handled. I'm afraid I'm at a very early stage with 2.3 and templating is an area that I haven't looked at yet.
Does that help any better than my first effort?
RAILS_ROOT will give you the absolute path to your root directory. Your app name will be the portion of the string after the final '/' which you can grab in any number of ways.
EDIT: Not quite enough to get the job done. Mike and Dan iron it out below.
I believe the preferred way now is to call Rails.root and no longer RAILS_ROOT. Apparently someone on planet rails has an aversion to uppercase or some similar important reason. As of 2.3.5 they both appear to work.
I was getting error
`template': undefined local variable or method `app_name'
ruby 1.9.2p290, rails 3.2.11, thor 0.18.0, Windows
but with rails 2.3 generator:
class DynanavGenerator < Rails::Generators::Base
(can't be sure whether this error happened under rails 3.0.9 or earlier)
changed class definition to be:
class DynanavGenerator < Rails::Generators::NamedBase
which then gave:
No value provided for required arguments 'name'
I then added a 'name' ("something" below):
rails generate dynanav something --force
which gave the original error, so I then added:
def app_name
#name.titleize
end
to the class and all was well.
As of Rails 4 (maybe earlier versions?), use Rails.application.class to get the application name. For example, if your app is named Fizzbuzz, here are a few ways you might access it:
rails(development)> Rails.application.class
=> Fizzbuzz::Application
rails(development)> Rails.application.class.name
=> "Fizzbuzz::Application"
rails(development)> Rails.application.class.parent
=> Fizzbuzz
rails(development)> Rails.application.class.parent.to_s
=> "Fizzbuzz"