We are currently using Ruby 1.9.3, Rails 3.1 (i know, we're working hard to upgrade all our applications).
We're using a module (let's call it 'OurModule' to add a method (let's call it 'OurAddOnMethod' to a model defined in a gem (let'd call that 'GemModel'). We have that module file living in the 'config/initializers' directory.
That file defines the module, and then calls this to include it in the model:
# Include the extension
GemModel.send(:include, OurModule)
When developing, things work well mostly, but periodically we will get an error that basically says "Undefined method 'OurAddOnMethod' in 'GemModel'". Restarting the server resolves the issue (for a while).
I'm assuming this is happening because the models are reloaded periodically with changes made in the development environment, and it appears that the initializers do not also get reloaded at that time..? It seems like this may not be the best way to set things up; it is quite frustrating to deal with.
Can anyone enlighten me on a better way to achieve this?
I ended up using wrapping the code in the following, and keeping it in initializers:
ActionDispatch::Callbacks.to_prepare do
# configure stuff or initialize
end
I feel really bad, i completely missed this question that seems to completely cover mine (linking to the answer that i used):
https://stackoverflow.com/a/8636163/287516
Related
As far as I know module attributes evaluated during compilation time. I was trying to follow this post about mocking API in Elixir:
defmodule Example.User do
#github_api Application.get_env(:example, :github_api)
def get(username) when is_binary(username) do
#github_api.make_request(:get, "/users/#{username}")
end
end
And I'm wondering if that's gonna work in production at all. As far as I understand when this module is compiled there's no access to the Application. So my question is: can I use module attributes to store some config values that come from Application.get_env?
You absolutely can. As long as the application was compiled using MIX_ENV specified to environment you want the application running under, and as long as that call evaluates to what you expect for that environment, it'll all work fine.
For a deeper look at how module attributes are affected by compilation for an almost identical case as what you've described, take a look at this blog post here.
I have a feeling this is a dumb one, but I've spent some time trying to figure it out and googling it, and to no avail. I'm trying to use a Ruby Gem in a Controller. I have included it in my Gemfile, run bundle install, seen it show up in my gems list, restarted my local server. But somehow whenever I try to call the gem ( rails_rrdtool ) It just tells me
uninitialized constant RrdgraphsController::RRD
app/controllers/rrdgraphs_controller.rb:22:in `show'
The spot in my code where it wigs is when I'm calling
RRD.graph
It's as though it doesn't know where the heck the gem is... However, I can use require to import it successfully into an irb session. So I know that it works, it's just not getting in there some how...
Bundler should be handling the inclusion of the gem I assume. Am I calling it in the wrong place?
This looks like a namespacing issue. Your error says it is looking for the constant inside of the current class: RrdgraphsController::RRD when it should be looking for a class outside of the current context.
Try prefixing the class name with a double colon to fully define the location of the class.
::RRD.graph #rest of your code
There's a good analogy of what this does in this other accepted answer. Basically it creates an absolute path so Ruby doesn't have to guess.
A simple question. Does this version support generators?
I wanted to test out using it and follow along with Ryan Bates screen cast which I uses a different version.
I've been playing with tables today and want to see how this works using the generator with a scaffold generated model and all its components.
Running rails g bootstrap:themed returns
Could not find generator bootstrap:themed
So I tried to reinstall with rails g install:bootstrap
Error similar which lead me to try to find if it supports these commands.
Thanks
It doesn't need generators for asset files, since we hook into the asset pipeline through the use of a Rails Engine - configuration options are available through the use of variables (use this as a reference, Sass variables are actually $x rather than #x and need to be defined before importing bootstrap), Sass' #extend, and Bootstrap's #makeRow and #makeColumn mixins, along with the other Bootstrap mixins.
Themed scaffold would be interesting but generally would be a pain to maintain - view scaffolding tends to get ripped apart pretty quickly anyway. Perhaps a 'sane' application.html.erb layout generator could be useful.
So yeah, we currently have no generators, don't need an asset one, themed scaffold probably not coming soon unless someone is interested enough to do the work on it, potentially a layout generator in the pipeline.
Checkout
https://github.com/decioferreira/bootstrap-generators
Seems to be what you are asking for.
-Rick
So I have a Rails 3.0 Engine (gem).
It provides a controller at app/controllers/advanced_controller.rb, and a corresonding helper at app/helpers/advanced_helper.rb. (And some views of course).
So far so good, the controller/helper/views are just automatically available in the application using the gem, great.
But I want to let the local application selective over-ride helper methods from AdvancedHelper in the engine (and ideally be able to call 'super'). That's a pretty reasonable thing to want to allow, right, a perfectly reasonable (and I'd think common) design?
Problem is, I can't seem to find any way to make it work. If the application defines it's own app/helpers/advanced_helper.rb (AdvancedHelper), then the one from the engine never gets loaded at all -- so that would work if you wanted to replace ALL the helper methods in there (without calling super), but not if you just want to over-ride one.
So that kind of makes sense actually, so I pick a different name. Let's call my local one ./app/helpers/local_advanced_helper.rb (LocalAdvancedHelper). This helper DOES get loaded, if I put a method in there that wasn't in the original engine's AdvancedHelper, it is available to views.
But if I put a method in there with the same name as one in the engine's AdvancedHelper... my local one NEVER gets called. It's like the AdvancedHelper (from engine) is earlier in the call chain than the LocalAdvancedHelper (from app). Indeed, if I turn on the debugger, and look at helpers.ancestors, that's exactly what's going on, they're in the reverse order I'd want in the ancestor chain. So AdvancedHelper (from engine) could theoretically call 'super' to call up to LocalAdvancedHelper (from app) -- but that of course wouldn't make a lot of sense to do, you'd never want to do that.
But what I would want to do... I can't do.
Anyone have any ideas, is there any way to provide this design, which seems perfectly reasonable to me, where an app can selectively over-ride a helper method from an Engine?
Anyone have any explanation of why it's working the way it is? I tried looking at actual Rails source code, but got lost pretty quick, the code around this stuff is awfully abstract split amongst a bunch of places.
This is pretty esoteric question, I'm pessimistic anyone will have any ideas, I hope you surprise me!
== Update
Okay, in order to understand what part of Rails code is being called where, I put a "def self.included ; debugger ; end" on each of my helpers, then in the debugger I can raise an exception to see a stack trace.
That still isnt' really helping me get to the bottom of it, the Rails code jumps all over the place and is pretty confusing.
But it's clear that a helper with the 'standard' name (ie WidgetHelper for WidgetController) is called by different rails code, to include in the 'master' view helper module for a given controller, than other helpers are. I'm wondering if I give the helper a different name, then manually include it in my controller with ("helper OtherNamedAdvancedHelper"), if that will change the load order.
We can use Module#class_eval to override.
In main app,
MountedEngineHelper.class_eval do
def advanced_helper
...
end
end
In this way other methods defined in engine helper are still available.
Thanks for your elaboration. I think this really is a problem. And it is still present in Rails 3.2.3, so I filed an issue.
The least-smelling workaround I came up with is to do a "half alias method chain":
module MountedEngineHelper
def advanced_helper
...
end
end
module MyHelper
def advanced_helper_with_extra_behavior
advanced_helper
extra_behavior
end
end
The obvious drawback is that you have to change your templates so that your helper is called. At least, you make the existence of extra behavior explicit there.
These release notes from Rails4 seem enticingly related to this problem, and potentially note it's been fixed:
http://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#helpers-loading-order
This is what I'm doing:
extract contents of my JRE's rt.jar
extract src.zip of my JDK (same version)
Now, if I copy Runtime.java from the extracted src folder and compile it using javac.exe without any modifications and then put it in the extracted rt folder to finally put everything back in a jar file using jar.exe, everything works as expected. The JRE runs fine.
However, if I make the slightest change to Runtime.java and compile it and put it in rt.jar, the JRE crashes whenever I attempt to start it. This is an example of a slight change that causes the silent crash:
/** Don't let anyone else instantiate this class */
private Runtime() {
System.out.println("This is a test.");
}
Instead of:
/** Don't let anyone else instantiate this class */
private Runtime() {}
Could anyone tell me why this is causing my JRE to crash?
Thanks in advance.
It's possible that System.out has not been initialised at the time that the Runtime() constructor runs. Usually console output is not considered a "slight" change, but at the wrong time it can invoke way too much stuff that may not be set up at all yet.
You're doing this all wrong. You can't distribute that modified JRE for a start, so it is only useful inside your organization . Install a SecurityManager and don't grant your codebase any of the RuntimePermissions you're trying to protect against.
#Tom - I advise you NOT to try to do this:
You cannot distribute the modified rt.jar file without violating the Sun binary license.
Even if you did, you would not be allowed to call it Java.
As you are finding, there are lots of complications that arise when you make changes, particularly when those changes might interfere with the JVM's behind the scenes initialization. And when things blow up during initialization, the JVM often cannot report the problem in an intelligible way.
If you do succeed in making the modified rt.jar work for one JRE, there is no guarantee that the same hacks will work for a different version.
Nobody in their right mind would knowingly use a modified JVM (especially one modified by a third-party) in a production app.
EDIT : judging from your other questions, I guess you are trying to reverse engineer or modify some third party Java application with a custom launcher. If you provided more information on what you were really trying to do, we might be able to suggest the right way to do it ... rather than using "desperate measures" such as modifying the JRE.
That's pretty strange, as I did the same trick with many classes in rt.jar in past.
Can you provide us with the crashed process output?