I have a Rails application, and I'm trying to export data, but directly through Pry because I only need to do it once.
Is this possible with Pry? I looked at the documentation but doesn't seem like there's an easy way to dump console data anywhere.
I have a hash, with nested hashes/objects, which I need to send over to a 3rd party for work with an API. They need a dump of the data so they can set up the receiving end of my call. I'm just going to do this in Ruby now, but it would have made more sense to dump the data through PRY, rather than edit my ruby object to dump the data, which I only need once.
If you can start the server from a local command-line, or SSH to the host and run an instance there, you can use Pry for this. Basically you need to add these lines to your code at the appropriate place:
require 'pry-debugger'; binding.pry
which will stop your code and put you at the Pry prompt. At that point you can enter something like:
require 'json'
File.write('test.data', hash.to_json)
Read the Pry.debugger documentation for information about using Pry with remote Rails sessions, which might work better for you.
You can also export any string into a file (here output.txt):
x = 'something funky'
.echo '#{x}' > output.txt
Just be careful with quotes in the string. These may lead to problems in the shell.
Related
I'm wondering if it's possible to start a Byebug session giving a starting point from a Rails console. I know I can insert a byebug statement wherever I want and start debugging, but I'd like to do something like this:
Byebug.start do
# entry point
User.find(12).problematic_method
end
Thanks.
I opened the class and override the problematic_method inside the Rails console and added the byebug statement where I wanted it. This way I don't have to change the running production code (I forgot to mention above I want to debug in production).
This workaround will be enough for my purposes. The only problem is that you don't have the debug code listing available for that method, but its fine.
That is not possible. What you can do, is write your code inside a .rb file and debug that file/script using byebug.
is a very beginner question but even tho i cannot find any helpful documentation online.
I'm working on Discourse application which is Ruby on Rails + Ember based.
I need to print out in my terminal (not in my view!) the value of a variable.
I try:
debugger
put varName
logger.debug varName
but none of them print anything in my console.
What i need to do is stop my console from running and print a value.
Like debugger; would do in javascript.
How can i do this simple task?
1) not sure if this change anything but the .rb file i try to debug is a "services".
2) yes, i read about pry, i installed it and add to my file:
require 'pry'
binding.pry
But i don't see anything happening in the console.
I'm using system(" ") on the rails console to execute an application that takes inside a file, processes it and outputs another file.
The application also logs statistics for said file on the terminal before closing.
My objective is to save those logged statistics as variables inside rails, although I'm not exactly sure how I can do that.
How can I save the logged statistics inside rails variables?
I don't think the system method is the best method to use here, as I think this would either return true or false. However to get back the value, you should try to use the backticks
statistics = `method to call on computer`
let me know if that works
Is there an easy way to log all method calls in a Rails app?
My main use for this would be in testing (and in debugging tests). I want to have more of a history than a stacktrace provides (for instance, when running rspec with the '-b' option).
It's easy to do. Just add 5 lines of code into your script/server:
#!/usr/bin/env ruby
set_trace_func proc {
|event, file, line, id, binding, classname|
if event == "call" or event == "return"
printf "%8s %s:%-2d %10s %8s\n", event, file, line, id, classname
end
}
require File.expand_path('../../config/boot', __FILE__)
require 'commands/server'
It's described at http://phrogz.net/ProgrammingRuby/ospace.html#tracingyourprogramsexecution
Your application will become quite slow and you might get more output than you want. You can easily add more conditions on file/class/function names to avoid printing unwanted stuff.
Perftools might give you what you're looking for. It analyzes the entire process and can give you a graphical view that looks something like this. Rack perftools profiler is a rubygem that uses perftools and makes it easy to integrate with a Rails application, so I would recommend going with that if you want to try it.
Firstly stacktrace IS every method call that was on the stack at the time an error occurred, what other history could you want besides this?
Secondly, to answer your question, no there is no easy way to log all method calls. You could up your log level all the way to debug which should give you more stuff in the logs, but this will only be things that someone has actually chosen to log, unrelated to method calls.
It probably wouldn't be that difficult to patch ruby in such a way that every method call will print some log statements before and after the method execution, but this will once again be similar to what a stack trace would give you anyway and potentially less since you won't get line numbers etc.
If you want more info than the stack trace, logging is the way most people would do it.
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.