Trouble on retrieving a constant's value stated in an initializer - ruby-on-rails

I am using Ruby on Rails 3.1 and I would like to understand why a constant's value stated in an initializer file sometimes is not retrieved as expected.
That is, in my ROOT_RAILS/config/initializers/initializer_name.rb file I have "simply" the following code:
CONSTANT_NAME = [
'value_one',
'value_two',
'value_three'
]
In a my view_file_name.js.erb file I have "simply" the following code:
<% logger.debug "#{CONSTANT_NAME.inspect}" %>
When I perform a HTTP request so to "trigger"/"run" the view_file_name.js.erb source code and then I go to check the log file, sometimes the CONSTANT_NAME is outputted, sometimes it isn't (in the latter case it outputs a [] value). I tried to restart the server many times but, after a while, the constant outputted to the log became [].
What is the problem? How can I solve that?
P.S.: I noted that the issue occurs mostly when I reload the page. This is a strange behavior and maybe there is something really subtle in my poor code that I can not fix. I think that the issue is related to the "process" to retrieve the CONSTANT_NAME value from the initializer file...

Related

How to extend the String class in a command line app?

I primarily work in Rails and I'm using a command line data conversion gem, "Mongify" and I am stumped about how to extend core classes in a Ruby cli app.
I want to extend the String class with an .is_date? method to check whether a string can be converted to a Date. I've got it working in the Rails Console,
I added a string.rb file to lib/ext with the following;
class String
def is_date?
begin
return true if Date.parse(self)
rescue
#do nothing
end
return false
end
end
Then in a Rails console I do a require 'ext/string' and it will work.
But I can't figure out how to get it to work in the Mongify cli app. I copied string.rb into the lib folder of the gem and I've tried adding require 'string' to a number of different files in the gem, but I keep getting undefined method errors.
Can someone point me in the right direction?
How about you require it from lib/mongify.rb like so:
require 'string/extensions.rb'
And then put your code in lib/string/extensions.rb
Let us know the exact undefined method errors you're getting in case this isn't the solution.
To help you with the debugging exercise that would give you the answer you need. Start by putting a breakpoint right before the place of the function call.
In the debugger, load the required document and then step past your breakpoint to the next one after the call has occurred.
Once you have this working, then start earlier in the stack trace – in a file that loaded before that one. Keep moving backwards until you get to a sufficiently early part in the load process of the gem, and make that be the place you load your code.

NoMethodError undefined method '-#' NoMethodError in Controller Ruby on Rails

Context:
I pulled the most recent code from the repository and tried to make sure that the changes I was about to push up were going to work with that version of the code. This is a Ruby on Rails application. Also worth noting is the fact that when running the main application that I pulled from on the web, this error does not show up. But if I run my branch or the main branch cloned onto my environment, the error always shows up for every url I try. So it is on my end.
Problem:
As soon as I go to localhost:3000, I get the following error:
NoMethodError in HomeController#index
undefined method `-#' for #<ActionDispatch::Response:0x64fd460>
What I've Tried:
I have asked my question on the #rubyonrails IRC channel and nobody was able to determine what was going on through the Full Trace (I haven't posted it here because I wasn't sure what was the best way to do that on here; it didn't look very good in the code block or block quote). I have looked at my HomeController's index method, which is defined as such:
def index
#groups = #current_user.groups
#things = Thing.where(:group_id => #groups.map{|e|e.id})
end
I have also Googled around and haven't found what I need to fix the problem.
What I've Learned So Far:
-# is an operator. Some people may receive a similar error in assuming that Ruby has the shortcut to
variable = variable + 1
that a lot of other languages have:
variable++
Here is an example of that case: Undefined method `+#' for false:FalseClass (NoMethodError) ruby
Question:
Does anyone have any further suggestions on how to find the issue here? Also, if I could easily put the Full Trace on here, formatted in an aesthetically pleasing manner, would someone tell me how? I'm at a loss with this one :(
Update (2/8/2013):
It seems that the issue does not necessarily reside in the HomeController nor home/index.html.erb View. I have attempted to access ANY url with a valid action and the same error occurs with "NoMethodError in..." changing to the corresponding [...]Controller#index.
Update (2/9/2013):
Since this error happens no matter what url I try to navigate to, I decided to look in the routes.rb file in the config folder. I ran my server through rubymine instead of the command line this time, which made it a little easier to read for me. I started looking through all the spit out and I noticed an interested line that consisted of:
["private-key looking thing"] [127.0.0.1] Started GET "/" for 127.0.0.1 at 2013-02-09 18:20:52 -0700
It seems like there is a syntactical error in routes.rb (that's my best guess at this point). This does not explain why this only is an issue on my local environment with the same code sets, but what else do I have to go off of?
Does anyone have any suggested things to be on the look out for while I sift through this file? Not really sure what to be looking for as far as errors are concerned. Rubymines inspection stuff converted all my double quotes to single quotes and doesn't really have anything else to complain about.
Thanks in advance,
Jake Smith
I am guessing it might as well be an syntactical error in the corresponding view page Home/index.html.haml .. I am suspecting there is unintended '-' in front of variable call. I tried to simulate a similar scenario in my rails platform and see following page on browser
undefined method `-#' for false:FalseClass
Correct lines of code
%h1 All Movies
= "filtervalue=#{#isFilterOld}"
= "Sortvalue=#{#isSortOld}"
Edited to simulate the error (observe the - in front of isFilterOld variable)
%h1 All Movies
= "filtervalue=#{-#isFilterOld}"
= "Sortvalue=#{#isSortOld}"
I have fixed the issue!
What fixed it:
Go to the directory where your gems are (for me that was C:\RailsInstaller\Ruby1.9.3\lib\ruby\gems\1.9.1)
Delete all gems except for bundler
Make sure you delete the gems from the /cache/, /gems/, and /specifications/ folders (I just deleted them from the /gems/ folder at first and bundle install indicated that it could still find the gems)
Run bundle install
Further Inquiry:
Does anybody have any idea why this worked? I don't know if at this point I can narrow down which gem was causing the issue because the app is working now (I can visit all the urls with corresponding views). If the issue comes up again, I will delete gems one by one to nail down which one was at least causing the issue for me. But if anyone has any insight on this, a more detailed answer would be greatly appreciated by many more people than just me, I think. Thanks to all who helped thus far!

Rails: "Stack level too deep" error when calling "id" primary key method

This is a repost on another issue, better isolated this time.
In my environment.rb file I changed this line:
config.time_zone = 'UTC'
to this line:
config.active_record.default_timezone = :utc
Ever since, this call:
Category.find(1).subcategories.map(&:id)
Fails on "Stack level too deep" error after the second time it is run in the development environment when config.cache_classes = false. If config.cache_classes = true, the problem does not occur.
The error is a result of the following code in active_record/attribute_methods.rb around line 252:
def method_missing(method_id, *args, &block)
...
if self.class.primary_key.to_s == method_name
id
....
The call to the "id" function re-calls method_missing and there is nothing that prevents the id to be called over and over again, resulting in stack level too deep.
I'm using Rails 2.3.8.
The Category model has_many :subcategories.
The call fails on variants of that line above (e.g. Category.first.subcategory_ids, use of "each" instead of "map", etc.).
Any thoughts will be highly appreciated.
Thanks!
Amit
Even though this is solved, I just wanted to chime in on this, and report how I fixed this issue. I had the same symptoms as the OP, initial request .id() worked fine, subsequent requests .id() would throw an the "stack too deep" error message. It's a weird error, as it generally it means you have an infinite loop somewhere. I fixed this by changing:
config.action_controller.perform_caching = true
config.cache_classes = false
to
config.action_controller.perform_caching = true
config.cache_classes = true
in environments/production.rb.
UPDATE: The root cause of this issue turned out to be the cache_store. The default MemoryStore will not preserve ActiveRecord models. This is a pretty old bug, and fairly severe, I'm not sure why it hasn't been fixed. Anyways, the workaround is to use a different cache_store. Try using this, in your config/environments/development.rb:
config.cache_store = :file_store
UPDATE #2: C. Bedard posted this analysis of the issue. Seems to sum it up nicely.
Having encountered this problem myself (and being stuck on it repeateadly) I have investigated the error (and hopefully found a good fix). Here's what I know about it:
It happens when ActiveRecord::Base#reset_subclasses is called by the dispatcher between requests (in dev mode only).
ActiveRecord::Base#reset_subclasses wipes out the inheritable_attributes Hash (where #skip_time_zone_conversion_for_attributes is stored).
It will not only happen on objects persisted through requests, as the "monkey test app" from #1290 shows, but also when trying to access generated association methods on AR, even for objects that live only on the current request.
This bug was introduced by this commit where the #skip_time_zone_conversion_for_attributes declaration was changed from base.cattr_accessor to base.class_inheritable_accessor. But then again, that same commit also fixed something else.
The patch initially submitted here that simply avoids clearing the instance_variables and instance_methods in reset_subclasses does introduce massive leaking, and the amounts leaked seem directly proportional to complexity of the app (i.e. number of models, associations and attributes on each of them). I have a pretty complex app which leaks nearly 1Mb on each request in dev mode when the patch is applied. So it's not viable (for me anyways).
While trying out different ways to solve this, I have corrected the initial error (skip_time_zone_conversion_for_attributes being nil on 2nd request), but it uncovered another error (which just didn't happen because the first exception would be raised before getting to it). That error seems to be the one reported in #774 (Stack overflow in method_missing for the 'id' method).
Now, for the solution, my patch (attached) does the following:
It adds wrapper methods for #skip_time_zone_conversion_for_attributes methods, making sure it always reads/writes the value as an class_inheritable_attribute. This way, nil is never returned anymore.
It ensures that the 'id' method is not wiped out when reset_subclasses is called. AR is kinda strange on that one, because it first defines it directly in the source, but redefines itself with #define_read_method when it is first called. And that is precisely what makes it fail after reloading (since reset_subclasses then wipes it out).
I also added a test in reload_models_test.rb, which calls reset_subclasses to try and simulate reloading between requests in dev mode. What I cannot tell at this point is if it really triggers the reloading mechanism as it does on a live dispatcher request cycle. I also tested from script/server and the error was gone.
Sorry for the long paste, it sucks that the rails lighthouse project is private. The patch mentioned above is private.
-- This answer is copied from my original post here.
Finally solved!
After posting a third question and with help of trptcolin, I could confirm a working solution.
The problem: I was using require to include models from within Table-less models (classes that are in app/models but do not extend ActiveRecord::Base). For example, I had a class FilterCategory that performed require 'category'. This messed up with Rails' class caching.
I had to use require in the first place since lines such as Category.find :all failed.
The solution (credit goes to trptcolin): replace Category.find :all with ::Category.find :all. This works without the need to explicitly require any model, and therefore doesn't cause any class caching problems.
The "stack too deep" problem also goes away when using config.active_record.default_timezone = :utc

AR.to_json Works in Console, Fails in Browser

I have this block of code:
users = Array.new
users << User.find(:all, :conditions => ["email like ?", "%foo%"])
users << User.find(:all, :conditions => ["name like ?", "%bar%"])
users.flatten!
users.uniq!
puts users.to_json :include => [:licenses]
When I run it using script/console, it returns exactly what you would think it should, a JSON representation of the Array of users that I found, flattened, and uniquified. But running that same line of code as part of a search_for_users method, I get this error
TypeError in ControllerName#search_for_users
wrong argument type Hash (expected Data)
and the line referenced is the line with the .to_json call.
It's baffling me because the code is verbatim the same. The only difference is that when I'm running it in the console, I'm entering the conditions manually, but in my method, I'm pulling the query from params[:query]. But, I just tried hardcoding the queries and got the same result, so I don't think that is the problem. If I remove the :include, I don't see the error, but I also don't get the data I want.
Anyone have any idea what the issue might be?
There are a few plugins and gems that can cause .to_json to fail if included in your controller. I believe that the Twitter gem is one of them (ran into a problem with this awhile back).
Do you have "include [anything]" or "require [anything]" in this controller?
If not, I'd suggest temporarily removing any plugins you're using to troubleshoot, etc.
Finally, what happens if you replace that entire controller action with simply:
%w(1 2 3 4 5).to_json
That should help you pin down what is failing.
Whenever code in tests or the console behaves different from production environment (which is a guess... you might be running your site in development mode), this calls for a load order issue. In production environment, all the models and controllers are preloaded, in other environments they are loaded lazily when needed.
Start your console with RAILS_ENV=production ./script/console and see if you can reproduce the error this way.
As cscotta mentioned, there are a couple of gems and librarys, that can interfere with .to_json, first to mention the functionality, that you get when you require 'json'. I personally ran into several issues with that.
Hope this helps
Seb

How to determine the value of a controller variable during execution in Ruby on Rails?

What is the best way for me to determine a controller variable's value during execution?
For example, is there a way I can insert a break in the code, and cause the value of the variable to be output to the screen (or the log)?
Yes. The easiest way is to raise the value as a string. Like so: raise #foo.to_s
Or, you can install the debugger (gem install ruby-debug), and then start the development server with the --debugger flag. Then, in your code, call the debugger instruction.
Inside the debugger prompt, you have many commands, including p to print the value of a variable.
Update: here's a bit more about ruby-debug.
If you have a controller instance variable named #foo, then in your controller you can simply do something like:
logger.debug "#foo is: #{#foo}"
Additionally, you can output the value in your view template using:
<%= debug #foo %>
I prefer using the inspect method like so:
raise #foo.inspect
It has more information than to_s, like the attribute values.
Summary from Jordi Bunster, John Topley, and Jaryl:
I. Quick and dirty way:
raise #foo.inspect
in your controller. Or
<% raise #foo.inspect %>
in your view.
II. Proper logging to you development.log:
logger.debug "#foo == #{#foo.inspect}"
III. Full-fledged debugging:
Install the debugger (gem install ruby-debug), and then start the development server with the --debugger flag. Then, in your code, call the debugger instruction.
Inside the debugger prompt, you have many commands, including p to print the value of a variable.
Raising an exception is the fastest way if you just need to look at a value, but it's worth the time to learn how to use the debugger properly. It's rare that you would only need to just see the value of a variable, you are likely trying to find a bug in your code, and that's what a debugger is for.
Sending the info to the development log is slower than either of the other two options here so far if you learn how to use the debugger (who wants to read through log files). Use the logger for production, you are going to want to see what the value was when somebody calls you up and says everything is broken.
Well, I usually prefer the standard error output
$stderr.print("whatever")
Its simple and does the job.
Add pry-moves to Gemfile: gem 'pry-moves'
Insert binding.pry where you want to stop
Type variable's name to see its value
Then continue by typing c, move to next line with n or perform other debugging actions until you will resolve the issue.

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