I'm currently trying to develop my first ruby gem and I'm already stuck. I used the "bundle gem" command to create the basic structure and read some tutorials but what I can't find is how to integrate ActiveRecord.
Where do I create my migrations?
Do I create the "db/migrations" folder within the lib folder or at the root?
And do I have to do anything in the Rakefile (I found some questions where the answer was something like "you have to create your own [my_gem]:db:migrate" or something like that.)
All I need is a way to create a gem, which defines ActiveRecord models (including the migrations of course), which can then be used by a rails app.
Any help on that one would be greatly appreciated!
Greetings, Flo
When building a gem to integrate with a rails project, you want to build a railtie engine. If you are using rails 3.0.x, use enginex, if you are using rails 3.1 you should be use the new generator:
rails g plugin new your-plugin-name
Then, inside your gem, you can just define models, inside the app/models/ folder and they will automatically be picked up.
Migrations is somewhat harder: for rails 3.1 it is ok if you define them in the correct folder, in rails 3.0 you will have to manually generate a task to copy the migrations to your code-base. Check this link where I answered that very question.
For more information on rails engines check this and this article.
getting the functionality of ActiveRecord can be done by:
require "rubygems"
require "active_record"
class User < ActiveRecord::Base
end
This should work.
Related
I've got some helper code (monkey patches) I tend to carry around from rails project to rails project via simply copying files or pasting code into the initializers folder.
I think a clean way to deploy different categories of my initalizer code would be to simply add gems to my project Gemfile that would do the equivalent of this for me. I'm not very skilled at creating gems or the deeper side of ruby on rails engineering so I just wanted to know if this were possible before I got started with it.
Yes, this is definitely possible. It should be probably enough to make a simple gem, put your monkey-patches there and require them in the gem entry point (e.g., if the gem is called foobar, then bundler will require lib/foobar.rb by default).
There is a guide on creating gems available in Bundler docs. In case you need to interact with Rails application configuration, you can take a look at Rails Engines.
Hi have an existing rails 4 app which is using a MySQL database.
I now need to add code that creates dynamically a new table for every object and its attributes.
I decided to use a No SQL solution for this. Initially I wanted to use Mongo DB since I was familair with this. However, my company supports only Cassandra/redis/solr. So I have to pick one of these.
I chose Cassandra but Im not finding any tutorials or examples on how to use it with an existing rails app with a MySQL DB.
I found this ORM for rails-Cassandra but no idea how to make it work with an existing Active record - mysql system.
Any ideas would be very appreciated.
Apologize this post has no code. But I couldnt find any answers for this issue on SO so please excuse if any mistakes.
thanks
ActiveRecord and Cequel will be independent.
As shown in their docs you extend a model's functionality by including the Cequel::Record module.
include Cequel::Record
In order to use it in rails you (obviously) need to add the proper gem in your Gemfile
gem 'cequel'
and create the configuration for the project
bundle exec rake cequel:keyspace:create
After that, you will have a config/cequel.yml from where you will define your settings (as you did in config/database.yml for your MySQL)
MySQL models will still use the ActiveRecord
class Foo < ActiveRecord::Base
...
end
while Cassandra ones will use the Cequel
class Bar
include Cequel::Record
...
end
Mac OS X 10.7.3 Lion,
Ruby 1.9.2,
Rails 3.2.2,
Sass 3.2.3
Following this tutorial:
http://activeadmin.info/documentation.html
Following this video tutorial
http://www.youtube.com/watch?v=tAxlrHcEg9U
I add the activeadmin gem, run bundle install, then run
rails generate active_admin:install
rails generate active_admin:resource POST
Only after creating the app/admin/posts.rb and trying to run either
db migrate
rails server
fails with the error
uninitialized constant Post NameError
with out that posts.rb file i am able to run the admin interface error free.
I tried moving the sass-rails gem out side of the :assets in my gem file and re-running bundle install as suggested in another question, but to no avail I still have the error
according to the getting started active admin tutorial "Post" is suppose to be a module name so i assume the code above is calling a class method (ActiveAdmin as the class, register as the method) and sending the module as a parameter and the block do end
Regardless the error is implying that RoR doesn't know what Post is. As if it does not exist. Being new to rails i do not know how to navigate well, meaning i do not even know where this ActiveAdmin source file is in order to dig through it for a method Post
Thank you for the consideration and your time, I appreciate it.
The linked tutorial assumes that you have already created a model named Post (and have run rake db:migrate to link it to the database). The purpose of the rails generate active_admin:resource Post command is to tell ActiveAdmin that you want it to consider the Post model in part of what it does.
Historically, you'll see models like Post and User in Rails a lot -- these are the commonly used examples of creating a blogging application (a user can create blog posts).
So, whatever models you have in your application can be registered with ActiveAdmin by replacing Post with the name of your model.
Another note: while generators like this tend to be forgiving, a Post is a model that is defined in post.rb and is linked to a SQL table called posts. Be careful with things like upper- and lower-case, and singular and plurals. In Rails they all fit together in a special way.
I want to learn how to create a rubygem with a generator etc.
When I create a gem, do I create a separate project?
The reason being, since it will have generators and hook into the lifecycle of a Rails 3 application, I want to create a test rails 3 application at the same time to see how things are working etc.
Can someone outline what I should do to do this?
For example, I'm using git, so what I want to do is, when I run a generator for my gem and it doesn't do what I want, I can then easily rollback to the previous version using git.
This will be a simple gem, just trying to get a feel for things and how I can hook into various parts of rails etc.
Use bundler to create the new Gem with the following command:
bundle gem foogem
Then go to the Gemfile of the application you're going to use and add something like the following:
gem 'foogem', :path =>'/path/to/foogem'
In this way you can easily test your gem inside your rails project.
I'm currently working on a couple of different gems both of which mainly consist of rails view helpers.
My problem is that some of these helpers require rendered rails templates to test the output - but I am unsure of the best way to stub a template, without a rails application. I presume that I should be able to leverage rspec-rails in some capacity, but i've been having trouble getting that to work without a rails app present.
Am I approaching this the wrong way? What's the current best-practice to test rails-specific features (in particular - things that happen only in the view) during gem development?
I use the excellent enginex gem, which helps you in setting up a gem skeleton with an embedded rails application for testing. This way you can easily test any rails dependency inside that application. To generate rspec tests run it as follows (default is test-unit):
enginex -t rspec your-gem-name
What I did to incorporate this into my gem, was run this inside some test folder, and copied the necessary files over to my gem. As an example, you could check it out inside my cocoon gem.
Hope this helps.