Suppose you want a hash with keys from an array and values from another array, use something like
ruby> ids = [1,2,3,4]
=> [1, 2, 3, 4]
ruby> names = ['Dan Brown', 'Stella', 'Parker']
=> ["Dan Brown", "Stella", "Parker"]
ruby> Hash[ids.zip names]
=> {1=>"Dan Brown", 2=>"Stella", 3=>"Parker", 4=>nil}
We can use a memcached server for centralized caching in our application. This server is handling all caching mechanisms. Rails is using the gem memcache-client by default. But here I am using the dalli gem. Because it is better than memcache-client, but one thing to say is I am not experienced this. By reading documents, I have concluded that. You just go through this dalli gem link, https://github.com/mperham/dalli. This is a super caching mechanism by Rails in production environments. The Only thing we need to do is
config.action_controller.perform_caching = true
Add the following in your gem file and do bundle install
$ gem 'dalli', '2.0.2' $ bundle install
$ sudo apt-get install memcached
$ sudo /etc/init.d/memcached start
config.cache_store = :dalli_store, 'YOUR_PRODUCTION_PUBLIC_DNS:11211',
{ :namespace => "app-YOUR_HOST", :expires_in => 1.day, :compress => true }
Here ‘YOUR_PRODUCTION_PUBLIC_DNS:11211’ is saying where your memcached server is running. Public DNS and the port number of the memcached server.
Take the rails console and experiment something like the following to know the MemCacheStore cache mechanism is working. If you are in localhost then do
ruby-1.9.2-p290 :003 > cache = Dalli::Client.new('localhost:11211')
=> #0}, @ring=nil>
ruby-1.9.2-p290 :004 > cache.set('testing', 1234)
=> true
ruby-1.9.2-p290 :006 > cache.get('testing')
=> 1234
Now you are ready to go
Suppose you have a need that is to download a file from amazon s3, that stored in http://s3.amazonaws.com//file.doc, if it is not accessable to public you will not get.
You can get an idea about Authenticated read by reading the following
(Reference: http://www.bucketexplorer.com/documentation/amazon-s3–access-control-list-details.html)
Amazon S3 allows users to store their objects in Buckets. All Buckets and Objects are associated with Access control policies. ACL is a mechanism which decides who can access what. ACL is the set of permissions of read,write and update on Object as well as Bucket on the basis of these ACLs user can perform operation of upload new files, delete existing objects.
Bucket ACLs are completely independent of Object ACLs. It means that ACLs set on a bucket can be different of ACLs set on any object, contained in bucket.
Amazon grants permission to four types of users:
So if you want private files from Amazon s3 access by, giving the correct url by giving the access key id and secret access key.
Eg:http://s3.amazonaws.com//file.docAWSAccessKeyId=EOKJGAKIAIHHMD3HP5OLLME5N4A&Signature=0ipwRz3sss6xnfAbebtigAGNOysdfdf1sDpKCl0%3D
If anyone access this url they can get the files. So here comes the use of expiring a request url. Create a url with access key id and secret access key and expires this after some seconds say 10 seconds.
Eg: http://s3.amazonaws.com//file.doc?AWSAccessKeyId=EOKJGAKIAIHHMD3HP5OLLME5N4A&Expires=1325481379&Signature=0ipwRz3sss6xnfAbebtigAGNOysdfdf1sDpKCl0%3D
aws-s3 is a Ruby library for Amazon’s Simple Storage service’s (S3) REST API. AWS::S3::Base is the abstract super class of all classes who make requests against S3.
AWS::S3::Base.establish_connection!(:access_key_id => '...', :secret_access_key => '...') The :access_key_id and:secret_access_key are the two required connection options.
ruby-1.9.2-p290 :058 > f = File.open(“my_file.txt”, “w”)
=>
ruby-1.9.2-p290 :059 > f.write(“This is the first line of my file\n”)
=> 34
ruby-1.9.2-p290 :060 > f.close
=> nil
ruby-1.9.2-p290 :061 > f = File.open(“my_file.txt”, “r”)
ruby-1.9.2-p290 :062 > f.read
=> “This is the first line of my file.\n”
ruby-1.9.2-p290 :063 > lines = IO.readlines(“my_file.txt”)
ruby-1.9.2-p290 :063 > puts lines.first
This is the first line of my file.
A useful link about ruby File manupulation is given below
Install ‘roo’ gem
$ sudo gem install ‘roo’
take the ruby console
$ irb
for example take an xlxs file and try to open
ruby-1.9.2-p290 :003 > require ‘roo’
if you get an error like
/home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo.rb:6: warning: already initialized constant VERSION
/home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo.rb:7: warning: already initialized constant LIBPATH
/home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo.rb:8: warning: already initialized constant PATH
LoadError: no such file to load — zip/zipfilesystem
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo/openoffice.rb:3:in `’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo.rb:71:in `’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from (irb):3
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/bin/irb:16:in `’
ruby-1.9.2-p290 :004 >
Then install the ‘rubyzip2’ gem
$ gem install rubyzip2
and open the file
ruby-1.9.2-p290 :003 > file = Excelx.new(“/home/prescience-toshiba/Documents/abhilash.raw.xlsx”)
output:
=> {[1, 1]=>”Name”, [1, 2]=>”Email Id”, [1, 3]=>”Alternate Number”, [1, 4]=>”Date of Birth”, [1, 5]=>”Mobile No.”, [1, 6]=>”Functional Area”, [1, 7]=>”Area of Specialization”, [1, 8]=>”Industry”, [1, 9]=>”Resume Title”, [1, 10]=>”Key Skills”, [1, 11]=>”Work Experience”, [1, 12]=>”Current Employer”, [1, 13]=>”Previous Employer”, [1, 14]=>”Current Salary”, [1, 15]=>”Level”, [1, 16]=>”Current Location”, [1, 17]=>”Preferred Location”, [1, 18]=>”Course(Highest Education)”, [1, 19]=>”Name”, [1, 20]=>”Email Id”, [1, 21]=>”Alternate Number”, [1, 22]=>”Date of Birth”, [1, 23]=>”Mobile No.”, [1, 24]=>”Functional Area”, [1, 25]=>”Area of Specialization”, [1, 26]=>”Industry”, [1, 27]=>”Resume Title”, [1, 28]=>”Key Skills”, [1, 29]=>”Work Experience”, [1, 30]=>”Current Employer”, [2, 1]=>”Rahel Robert”, [2, 2]=>”rtrobert@yahoo.com”, [……………………..
ruby-1.9.2-p290 :003 > require ‘roo’
/home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo.rb:6: warning: already initialized constant VERSION
/home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo.rb:7: warning: already initialized constant LIBPATH
/home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo.rb:8: warning: already initialized constant PATH
LoadError: no such file to load — zip/zipfilesystem
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo/openoffice.rb:3:in `’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/gems/ruby-1.9.2-p290@rails31rc/gems/roo-1.10.0/lib/roo.rb:71:in `’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require’
from (irb):3
from /home/prescience-toshiba/.rvm/rubies/ruby-1.9.2-p290/bin/irb:16:in `’
ruby-1.9.2-p290 :004 >
Instead of roo do
ruby-1.9.2-p290 :004 > require ‘roo/excel’
This works fine. If you want zip gem then install it.
$ gem install rubyzip2
Then do
ruby-1.9.2-p290 :001 > require ‘roo’
=> true
Open your .bashrc file.
And replace the following line
[ -z “$PS1” ] && return
with
if [[ -n “$PS1” ]]; then
Now add this to the last line of the file
if [[ -s $HOME/.rvm/scripts/rvm ]] ; then source $HOME/.rvm/scripts/rvm ; fi
fi
This loads RVM into a shell session.
If already have rvm then
Update rvm
if this shows error like ‘downloaded does not match it’s md5 checksum’
then run
For ruby 1.9.2 we want the packages it lists under the MRI & ree section. Let’s install those now.
Do rvm list known to know all ‘Ruby implementation made available through RVM’
Then install latest stable release of ruby
You can see the ruby versions installed and currently using ruby version by
To list default ruby
You can change it by
for default : rvm –default 1.9.2-p180
Install rails stable release and then rails 3.1
Start by creating our gemsets
See available gem sets by
If any confusion with rails31 gemset delete it
And create rails31rc
As a best practice, remember to always use one gemset per project*.
Now we have multiple gem set installed. Now set the different gem set for ruby versions.
Install Rails 3.0.7
Select the gemset for Rails 3.1
for default $ rvm use 1.9.2-p180@rails31rc –default
if not found
Switching from one project to another, from a client to a personal project, from testing the release candidate to developing using the latest stable version, always having to manually switch from using a gemset to another can impact productivity. The project .rvmrc files can increase the development speed by setting up our project’s ruby environment when we switch to the project root directory.
The rule of thumb here is to use a .rvmrc file for each project, for both development and deployment.*
if you go to your app folder ‘$ cd myapp’ then you can see like
There are three types of .rvmrc files
1) system : on /etc/rvmrc
2) user : $HOME/.rvmrc
3) Project : .rvmrc
with mysql as database
If u get error like
“”” home/user/.rvm/gems/ruby-1.9.2-p180@rails31rc4/gems/execjs-1.1.2/lib/
execjs/runtimes.rb:43:in `autodetect’: Could not find a JavaScript
runtime. See https://github.com/sstephenson/execjs for a list of
available runtimes. (ExecJS::RuntimeUnavailable) “””
Then you need a javascript engine to run your code…
try installing rubyracer (Embeds the V8 Javascript interpreter into Ruby.)
in your Gemfile add
gem ‘therubyracer’
and do bundle install
Start unicorn server
This program has a major method ‘search in file’ that accepts a folder path as a parameter. Next initialize whatever variables we want.
Then calls a method ‘iterate_through_dir’ which has two parameters in ruby and one in python, ‘folder path’ and instance variable ‘file_array’. In python we initialized a gobal variable ‘file_array’. But in ruby ‘@file_array’ is an instance variable. This method finds file paths of files included in the folder we have given, say ‘sample_folder’. Using the class method ‘glob’ in ruby and os module’s listdir in python we can find all the files and folders that inside sample_folder. Next check it is a file or a folder. If it is a folder we need to iterate through that folder(use recursion ) and get the file paths of files inside the folder. Else it is a file push that file path into our instance array ‘file_array’.
def iterate_through_dir(dir_path, file_array)
file_paths = Dir.glob(dir_path + “/*”)
file_paths.each do |f|
if File.file?(f)
file_array.push(f)
else
iterate_through_dir(f, file_array)
end
end
end
def iterate_through_dir(dir_path):
file_paths = os.listdir(dir_path)
for i in file_paths:
path_to_dir = dir_path + “/” + i
if os.path.isdir(path_to_dir) == True:
iterate_through_dir(path_to_dir)
else:
file_array.append(path_to_dir)
Now we got all the file paths of files inside the nested folder sample_folder in @file_array / file_array. Take each element in the @file_array / file_array, and open that file in read mode. Call ‘f.read’ in ruby and ‘f.read()’ in python to get the file contents as a string.
———
@file_array.each do |file_path|
f = File.open(file_path, ‘r’)
file_contents_in_string = f.read
———
———
———
for i in file_array:
f = open(i, ‘r’)
file_content = f.read()
———
———
Then call ruby-‘.match’, python – ‘re.search'(import regular expression module first -import re) on file content string to find the string inside the file. If you find the string then put it in an array. If you can’t find then put it in an another array. Before that find the file extensions to get the different type of files and append that file paths to different arrays.
———
if (file_contents_in_string[0..500].match(“your string”))
files_has_string << file_path
else
file_extension = File.basename(file_path).split(‘.’)[1]
if file_extension == ‘rb’
rb_files_has_no_string << file_path
elsif file_extension == ‘erb’
erb_files_has_no_string << file_path
else
unknown_files << file_path
end
end
end
———
if re.search(‘find_this_string’, file_content[0:500]):
files_has_string.append(i)
else:
& file_extension = os.path.basename(i).split(‘.’)[1]
& if if file_extension == ‘rb’:
rb_files_no_string.append(i)
elif file_extension == ‘erb’:
erb_files_no_string.append(i)
else:
unknown_files.append(i)
At last call the print_results method to print results.
——–
print_results(@file_array, rb_files_has_no_string, erb_files_has_no_string, unknown_files)
end
print search_in_file(“/your/path/to/nested/folder”)
——–
print_results(rb_files_no_string, erb_files_no_string, unknown_files)
print search_in_file(“/your/path/to/nested/folder”)
The method ‘print_results’ accepts four arrays and prints the results accordingly.
If you have an array,
array = [1,2,3,6,3,”A”,3,1,”A”, 5,6,”A”,7,7] then do
array.uniq = [1, 2, 3, 6, “A”, 5, 7]
very easy in ruby right?!!
To know about sphinx type
$ search
If you are getting error when starting sphinx make sure that the ‘indexer’,’searchd’,’search’ is under /usr/local/bin or under where sphinx specifies.
You are now ready to go…
The Rails Drop 