In the documentation for Rails::Plugin (for Rails 3), I'm reading the following:
"... you actually cannot declare a Rails::Engine inside your Plugin, otherwise it would cause the same files to be loaded twice. This means that if you want to ship an Engine as gem it cannot be used as plugin and vice-versa."
Can anyone be more specific about exactly what files get loaded twice? I have declared a plugin/gem as Engine, and it works fine also being put inside vendor/plugins (and I'd like to keep it this way), in spite of the statement above. I simply want some clarity on why (and whether) this is not a good thing to do.
Thank you!
I don't have an exact answer myself, but this subject is covered in this resource which I have found helpful:
https://gist.github.com/e139fa787aa882c0aa9c
Related
First, I am fairly new to Ruby/RoR and so you'll have to forgive me for any wrong terminology, but hopefully I'll get my point across.
I built an ruby app that I am needing to add an extremely simple UI layer using rails. Read up on a previous post of mine that explains the project thoroughly to give you good an idea of what it does. Specifically take a look at the tree outline that I pasted in so you see the existing file structure for the project.
What I need to know, is how to convert this existing project into a rails app? My experience in building something with rails has always started out with rails new app_name, but never anything like this. Any tips would be appreciated.
I saw your parser script, and it is not a daemon (a program that keeps running indefinitely in the background), right?
If I'm right, then you have several options:
The easiest option
Just build a rails application using rails new app_name, and inside some controller action, make a system call to run your script
class SomeController
def some_action
succeeded = system(:ruby, '/path/to/main.rb', '/path/to/some.txt')
# Do some rendering stuff here based on the result of the system call
end
end
This approach is somehow nasty for me, and it's not performant because each system call reads your ruby script and compiles or interprets it then runs it.
The harder option
Refactor your script so that it's features can be wrapped into a gem.
Then you install that gem, require it in your rails app, and use it.
I saw your original ruby script is almost there, it shouldn't be that hard to make it become a gem.
Rails is just "something" on top of Ruby. Especially, you can use any plain ruby objects inside of Rails, anywhere, and this is nothing unusual (google "PORO").
In your case, I would make a simple Rails app in the way you have mentioned yourself with rails new. Then trivially refactor your existing code until you have a simple, standalone class that does what you need to be done but takes its input/output from simple ruby data structures (i.e., method arguments, return values, no global state, no file operations). Then you can use that class from inside your Rails controller (taking input from a HTML form, rendering output to HTML), and also from inside your script (reading input from a file or STDIN, rendering output to STDOUT).
Where you put that class is up to you. In the MVC paradigm, it is not "C" or "V", and one could argue about whether it's "M". So put it into app/models/ or lib/, whatever you like more.
These were great answers and I'm sure they would have worked perfectly. However, they were a little bit more complex than what I was looking for.
What I ultimately ended up doing was just cd into the directory above where the ruby app was located and then just simply ran rails new app_name. Rails will ask if you'd like to overwrite any files that exist already. From there I just integrated my script into the controller actions and created the views.
I'm building a social network and have been using the gem community_engine but have been having trouble implementing the large amount of customization that I need for my app. I figure this will make it easier for me to override and add methods, as well as help me to better understand and learn from the code since I will be able to actually see all of it in action.
So far in my attempt I downloaded the source code, added the default bin directory and config files that were missing, as well ass all the gem dependencies.
What else do I need to do to get the app to work? I realize that there may still be a lot and that it might not be easy to explain, but at the very least is there any sort of documentation out there that might help me understand how to convert the gem to a Rails application?
Heres the community_engine repo: https://github.com/bborn/communityengine
Because this idea may draw some criticism, I'll add that I was originally building the app without any huge plugins accept for devise however I'm running out of time to finish this.
More stuff I've tried:
Moving files to a new rails app, got server to run but encountered many seemingly random errors, fixed a few but more just seem to pop up that I cant figure out:
I also took a look at http://guides.rubyonrails.org/plugins.html but this gem seems to go beyond that.
I would suggest that you clone the gem and begin copying files from the gem into your a new Rails application.
The engine gem probably has a similar structure to a Rails application, so you should be able to move the files from the corresponding folder to the same folder in your Rails root folder.
You may need to move gem files out of modules, change namespaces etc. Relevant folders to look at files you'll want to include might include app/ config/ db/, any gem dependencies in Gemfile or the gemspec file, as well as spec/ or test/.
Beyond that I think there's no silver bullet answer to your question, you're just going to have to work through problems until you have this up and running, and perhaps ask subsequent questions if you hit on an obstacle that you don't get beyond.
I think what you're looking for is a way to hook your Rails Engine into a rails app. The Hooking Into an Application section of the Getting Started with Rails Engines guide should be exactly what you're looking for.
Here are two additional resources on Rails Engines.
A Guide to Rails Engines in the Wild
Rails::Engine - Ruby on Rails API
I am developing my first rails site (yup, i am a rails idiot).
I'm writing a blog, and i got to the comments part.
I installed acts-as-commentable-with-threading ( GitHub ), i made and ran the migration like the install instructions said.
I have added acts_as_commentable to my Posts model and i have a Comments controller
When i add
#comment = Comment.build_from(params[:id],1, params[:body] )
I get the error.
undefined method `build_from' for #
Clearly i am doing something terribly wrong, and i don't really get the example. What should i be feeding to build_from? Can somebody explain this plugin step by step? :)
Or is there an easier way to get simple threaded comments?
Did you by chance define your own comment model? If so that is going to completely override the model from the plugin that defines build_from in the first place. I ended up getting around this by creating a module with the extra stuff I wanted then creating an initializer to include it, which works perfectly.
As an aside, the first parameter to build_from needs to be the actual commentable object the comment is to be connected to, not just an id.
I'm currently using this plugin in production and can assure you it works :)
Besides the reason of not restarting server (btw you shouldn't use nginx + passenger for development, simple mongrel or thin will do the job better in this case) I can think of two more:
You didn't install plugin (or something wrong happened during installing). However this is unlikely as you could run migration ok right?
You have comment model in app/models and rails doesn't load it from plugin. In this case you might want to try requiring file with plain old require.
I'm developing a ruby module that I include in my rails app. I want it to be reloaded automatically when it changes. I've done extensive googling, and looked at the various questions here that discuss it, but they all seem out of date or wrong.
How do I get an external module to be reloaded in rails when it changes? I've tried adding its name to ActiveSupport::Dependencies.unloadable_constants, but after I type reload! in the console, I can no longer refer to that symbol without a NameError: uninitialized constant foo, even if I do another require 'foo_module'. Does anyone know how to get this working?
Note: here is one possible dup, but note in the comments to the 'answer' that it never solved the problem for modules. There's also this question which has a dead link in the answer, and finally this one, which also doesn't solve it.
I found how to do this:
Make sure FooModule is in lib/foo_module.rb.
Use require_dependency to require your external library in lib/foo_module.rb.
These steps are both required, and no others are required.
There are two separate problems here.
The simpler of which is that you are using require, when you want load.
require will evaluate the code in a file once, no matter how many times that file/module is required.
load will evaluate the code in a file each time that file is loaded.
require is preferred to load used so that the files are not evaluated multiple times when many files depend on them.
The short version is that load can be used to reload modules that have already been loaded by require.
The more complicated problem is automatically reloading a module on change.
One of the possible duplicates listed in the question links to here. Which suggests prefixing any code that depends on your module with a conditional load of your module if it has changed since loading. You'll need to use a global variable to keep track of when a file was loaded.
N.B.: this should not be used on a production server, but should be fine on a development server or console.
I spent sometimes to research this issue as well.
Here's my findings on how to auto-reload require files in Rails without restarting server.
The solution is now available as a Ruby gem require_reloader.
I am testing AlumniOnRails (http://rubyforge.org/frs/?group_id=2959&release_id=17170) which is based on Rails 1.2.6 (I know it's outdated) and managed to get it up, installed the required gems, created and migrated the data and most of the basic alumni functionalities are up but one, the part that is broken seems to be missing a library and yet I can't seem to find it after a few reasonable searches.
The logger shows no such file to load -- collections/sequenced_hash with a line within the controller having the code of require 'collections/sequenced_hash which is quite obvious that the sequence_hash library is missing.
A few searches on Google shows a few references, one with the closest pointer is http://collections.rubyforge.org/classes/SequencedHash.html but unfortuntely the source link is dead. Does anyone keep this kind of old file or point me to somewhere it is? Thank you
Somebody answered this over ruby forum and it works:
gem install collections