The last couple of times that I've used 'rails generate scaffold [ModelName]' everything has been generated except that the controller is blank. It contains no methods at all. It's easy enough to copy that in from other sources, but I'm wondering what is going on.
The only unique thing about this application for me is that it's using the ActiveAdmin gem.
Any suggestions for how I could get this working as expected again?
+1 to hajpoj, but there are a couple additional steps you could use to troubleshoot.
What does rails generate scaffold_controller give you? My first suggestion to be to isolate the controller generator and go from there.
Following that, I would actually look in the Rails generator code at the point of controller generation and work backwards from there. Here is (I believe) the entry point, from there, you can follow the code to where things are failing. This is, obviously, not the easiest path, but would probably teach you a lot about the rails internals.
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 am new user to ruby on rails.
I have some question please give the answer as early as possible
1) Is it possible to create web application without using *rails new application_name* command? means creating required folder and file manually?
2) I want to create application without using scaffold and generator, so everything is created manually...I searched but not get a link to do it...
You really should be using rails new (appname) to generate your project directory.
From there, you do not need to generate a scaffold. If you want to go slightly less abstract and create some things manually you can use rails generate resource (resource name).
If you want to go even less abstract then that, you can use rails generate model (model name) and rails generate controller (controller name) and rails generate migration (migration name). Within this level of abstraction, you can specify options such as methods you want the model to have or columns you want the migration to add.
And the least abstract(most manual) would be if you make these files yourself (like actually going in and creating new folders/files for models, controllers, etc.)
So on an order from most abstract to least:
1) generate scaffold
2) generate resource
3) generate model/controller/migration
4) creating the files/folders without rails
Most developers are usually working with the #2, #3, or #4 layers (remember it is always a tradeoff between eliminating a lot of time off by not having to manually create the same code over and over again and flexibility).
rails new app-name creates tons of files and folders which are necessary for the app to run. You would waste tons of time writing them yourself. Read as "reinventing the wheel".
You can simply create a controller and view file. Add the corresponding route. Start the server. Voila. You will have it. Most intro-articles showcase Scaffold to show the power of Rails i.e how much can be achieved with few lines of code.
I have a Rails app which contains a single controller(with a method) and a single view page .I would like to avoid all the unnecessary files in my app to keep this in a simple way. I need an app with controller,routes and views. So how should I scaffold my Rails 3 app, so that it contains only a minimal information?
If you are working on a real simple app, probably you the best fit would be sinatra
That is not rails, but implement with ruby.
HTH
You can manually create the files, especially when you only need a small portion of what the scaffold would create.
1) Add a statics_controller.rb to the app/controller directory. If you literally only need one page, you can simply use the index action (name your method index).
2) Add an index.html.erb (or .haml) to the app/views/statics/ directory.
3) In your config/routes.rb add the line get '/statics' => 'static#index'. You can append , as: 'your_preferred_url if you want to define your own url.
In all of the above, replace "static" with whatever name you think is appropriate. You would also need to add a model and migration if you plan to interact with a backend database.
I personally feel its good to not use scaffolding initially when you are new to rails so that you fully understand what they are doing. Scaffolding is not really doing anything fancy or magical. Its often just creating empty files in the correct directories (like I outlined above).
You can use the rails scaffold to be very specific in which part of MVC you create. For example,
$ rails generate controller Comments
or
$ rails generate model Comment commenter:string body:text post:references
I would highly recommend reading the entire Rails Getting Started Guide. But there is a specific section on generating a controller with scaffold.
Since Rails 6.1. running rails new --minimal gives you an application without all the bells and whistles like action mailer, action mailbox, action text, action job, active storage, action cable, ... and the accompanying configuration and stub files. It then has an ApplicationRecord, ApplicationController and the basics for an HTML view.
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 am learning Ruby on Rails so I'm sure I'll find this out sooner or later.
Why would the scaffold method be deprecated in version 2 of Rails?
The scaffold method went against the spirit of scaffolding, which is meant to give you a starting point that you are supposed to build upon for your own needs. By generating the scaffold dynamically, there is nothing for you to edit.
The new way with the scaffold generator lets you edit the scaffolded files so you can use it to build what you actually need.
I am assuming you are referring to Dynamic Scaffolding, as the scaffold generator is still around and going strong.
David Heinemeier Hansson is on record as saying that Dynamic Scaffolding looked great in demos, but since the whole point of Dynamic Scaffolding was to teach people to use rails, abstracting it away in a single line of code was more a curse then a blessing, as no one uses Dynamic Scaffolding in production code . . . just for demos and tutorials.
If you have a copy of AWDWR handy, you can read about his whole explanation on about p81 in the latest(3rd) edition (I didn't want to copy paste).
You can still:
script/generate scaffold model_name
to generate your scaffolded model.
There is however still a Rails plugin out there that will do just what the scaffold method did before. It's called ActiveScaffold.
Because people thought it was supposed to be used for production, which would be a horrible idea. Instead you generate a scaffold which you can then easily edit and get it production ready from there.