Category Archives: ruby on rails

Ruby on Rails programming tips

git and dreamhost : refusing to update checked out branch: refs/heads/master

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Problem
After dreamhost decided to move my account that hosted the git repository to a new server, first time I’ve tried to push some changes to the git repository I was faced with the followng error:

Counting objects: 13, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (7/7), done.
Writing objects: 100% (7/7), 699 bytes, done.
Total 7 (delta 6), reused 0 (delta 0)
error: refusing to update checked out branch: refs/heads/master
error: By default, updating the current branch in a non-bare repository
error: is denied, because it will make the index and work tree inconsistent
error: with what you pushed, and will require 'git reset --hard' to match
error: the work tree to HEAD.
error:
error: You can set 'receive.denyCurrentBranch' configuration variable to
error: 'ignore' or 'warn' in the remote repository to allow pushing into
error: its current branch; however, this is not recommended unless you
error: arranged to update its work tree to match what you pushed in some
error: other way.
error:
error: To squelch this message and still keep the default behaviour, set
error: 'receive.denyCurrentBranch' configuration variable to 'refuse'.
To ssh://dh_user@dh_domain/home/repository_path/projects/project.git

Solution
After searching and finding out various solutions to solve the problem, none of which was specific to a server move, I’ve tried the following:

  • Followed the steps here to set up a new repository project_asm.git
  • went to local project changed the config file to add the new remote repository
  • issued git push new_remote master
  • make a code change and then git push

And everything should work as normal again.

Rails – Mysql::Error: Got error 28 from storage engine

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Problem
Trying to access your rails application in your development pc, you get the error:

Mysql::Error: Got error 28 from storage engine

in your console.

Solution
It turns out that this specific error is a MySQL error, indicating that you have run out of space in the partition that the MySQL server stores its files (/var/lib/mysql).
Looking at the folder there, you can see a very large file called ibdata1.
This file holds all the information about your InnoDB tables and transactions in your MySQL. According to other posts after a Google search, it seems that this file cannot be reduced in size either by removing/truncating your tables or deleting databases that you don’t need. There are quite a few solutions out there if you really need to keep a backup of your databases, but if you only using your database for development and you DON’T NEED (!!) your data or tables, you can move this big ibdata1 to another partition for backup and restart your mysql, that will create a new file.

Testing Active_Mailer with GMail in development

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Problem
You want to test your email configuration and be able to send emails in your development environment, using a GMail account in a Rails application using 2.3.2.

Solution
Start your console in your development environment:

./script/console

Add the following replacing your GMail details:


ActionMailer::Base.smtp_settings = {
:enable_starttls_auto => true,
:address => "smtp.gmail.com",
:port => 587,
:domain => "your_gmail_domain",
:authentication => :plain,
:user_name => "your_gmail_user_name",
:password => "your_gmail_password"}

Add a simple email class:


class MyMailer < ActionMailer::Base def test_email @recipients = "an_address_to_sent_to@domain.com" @from = "address_from@your_google_domain.com" @subject = "test from dev console" @body = "this is the body" end end

and to finally test the email:


MyMailer::deliver_test_email

if it doesn't return with an error but with something like:


TMail::Mail port=#TMail::StringPort:id=0x..fdab4cee0 bodyport=#TMail::StringPort:id=0x..fdab4a9ec

then it should be working so add the configuration to your environments/development.rb

config.action_mailer.smtp_settings { ... }

Deploying a Rails project in a server that hosts the git repository

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Problem
You want to deploy your project in a server (dreamhost), that also hosts your git repository. When you try to do that by only setting the set_repository, you get errors like ‘permission denied, please try again’, even though if you try to checkout the git repository on your server works.

Solution
Set your :repository as a file in your host as in:
set :repository, "file:///home/username/git_on_server/projects/repo_name.git"

Then also set up your local_repository, as in:
set :local_repository, "user_name@server_domain_name:/home/username/git_on_server/projects/repo_name.git"

Rails Passenger Staging environment problem in Dreamhost

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Problem
You want to deploy your rails application using Passenger in Dreamhost, but on a staging environment. It doesn’t work just changing your Capistrano recipe or your environment files, as the default environment for passenger is ‘production’.

Solution
Looking at the Passenger documentation here, there are four different ways of achieving that by changing the RailsEnv option. If you don’t want to change the Apache configuration files, and as long as the option AllowOverride is on (which should be on Dreamhost), then you would need to create an .htaccess file in your application’s public folder with the following:

RailsEnv staging

God gem problem unpacking with Rails 2.3.2

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Problem
When using the god gem in a Rails 2.3.2 application, when you unpack (freeze) the god gem with :

sudo rake gems:unpack

it creates the god drectory in vendor/gems with root owner, and group permissions.

Solution
Remember to change owner and group for the folder

sudo chown -R user_name vendor/gems/god-0.11.0
sudo chown -R user_name vendor/gems/god-0.11.0

Help! I’m getting the message “libMagickWand.so.1: cannot open shared object file: No such file or directory” I know ImageMagick is installed! What should I do?

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Problem
Cannot install RMagick as there is an error about nob being able to find some shared libraries.

Solution
After reading the RMagick installation FAQ it seem there is a problem with the LD_LIBRARY_PATH that cannot find the needed libraries as they are installed in /usr/local/lib instead of /usr/lib.
Doing a quick search revealed that people suggest that the LD_LIBRARY_PATH shouldn’t be changed, for various reasons.
So, the quick solution is to create a couple of symbolic links for the libraries that cannot be found, ie:

sudo ln -s /usr/local/lib/libMagickWand.so.4 /usr/lib/libMagickWand.so.4
ln -s /usr/local/lib/libMagickCore.so.4 /usr/lib/libMagickCore.so.4

Rails find case sensitive search

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Problem
You want to use find in Rails for a case sensitive search. For example in your authentication logic you have something to find the user to login as in:
u=User.find_by_login(‘username’)
If you don’t want to limit the available logins with case insensitive validation in the model, then the above code will not work if you have ‘Username’ and ‘username’ as available logins, as the find will only return one of them.

Solution
Change the find method to use the BINARY keyword in your database (only used with MySQL), as in the following:
u=User.find(:first, :conditions => [“BINARY login = ?”, login])

406 Not Acceptable – Princely – Dreamhost

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Problem
You get a ‘406 Not Acceptable’ response from the web server when you try to use the princely plugin for generating pdf on a Ruby on Rails application hosted on dreamhost.

Solution
Having tried the ‘Extra Web Security’ settings in dreamhost Web panel, and setting them on/off did not get very far.
Also setting up an .htaccess file didn’t seem to make any difference.
So the mod_security settings did not seem to be the cause of the problem.
Having a look at the apache error log files which in the case of the dreamhost ps are in /usr/local/dh/apache2/logs/apache2-ps_name it turns out that the problem was that the path for the prince binary was not setting up correctly in the file vendor/plugins/princely/lib/prince.rb on line 26.
A quick hack to make it work until finding the reason for the problem is to hardcode the path to the prince binary, so:
@exe_path = `which prince`.chomp
if @exe_path.nil?
@exe_path=’/usr/local/bin/prince’
end

Could not load SystemTimer gem, falling back to Ruby’s slower/unsafe timeout library: no such file to load — system_timer

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Problem
You have the error showing up after starting either the server (./script/server) or the console (./script/console).
For my particular case it started appearing after installing the Rails 3.0 beta3 version, and in an application developed with Rails 2.3.2.

Solution
Just install the system_timer gem:
sudo gem install system_timer