Ruby pearls and gems for your daily routine coding tasks

This is a list of ruby pearls and gems, that help me in my daily routine coding tasks.

1. Retain only unique elements in an array:

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1. a = [1, 1, 2, 3, 4, 4, 5]  
2.   
3. a = a.uniq # => [1, 2, 3, 4, 5]  

a = [1, 1, 2, 3, 4, 4, 5]

a = a.uniq # => [1, 2, 3, 4, 5]

2. Command line options parsing:

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1. require 'optparse'  
2. class Optparser  
3.   
4. def self.parse(args)  
5.   options = {}  
6.   OptionParser.new do |opts|  
7.     opts.banner = "Usage: example.rb [options]"  
8.   
9.     opts.on("-v", "--[no-]verbose", "Run verbosely") do |v|  
10.      options[:verbose] = v  
11.     end  
12.   
13.    opts.on("-o", "--require OUTPUTDIR", "Output directory") do |o|  
14.      options[:output_dir] = o  
15.    end  
16.   
17.    options[:source_dir] = []  
18.      opts.on("-s", "--require SOURCEDIR", "Source directory") do |s|  
19.      options[:source_dir] << s  
20.    end  
21.   
22.    end.parse!  
23.   
24.    options  
25.   end  
26. end  
27.   
28. options = Optparser.parse(ARGV) #pp options  When executed with -h, this script will automatically show the options and exit.    

require 'optparse'
class Optparser

def self.parse(args)
  options = {}
  OptionParser.new do |opts|
    opts.banner = "Usage: example.rb [options]"

    opts.on("-v", "--[no-]verbose", "Run verbosely") do |v|
     options[:verbose] = v
    end

   opts.on("-o", "--require OUTPUTDIR", "Output directory") do |o|
     options[:output_dir] = o
   end

   options[:source_dir] = []
     opts.on("-s", "--require SOURCEDIR", "Source directory") do |s|
     options[:source_dir] << s
   end

   end.parse!

   options
  end
end

options = Optparser.parse(ARGV) #pp options  When executed with -h, this script will automatically show the options and exit.  

3. Delete a key-value pair in the hash map, where the key matches certain condition:

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1. hashMap.delete_if {|key, value| key == "someString" }  

hashMap.delete_if {|key, value| key == "someString" }

Certainly, you can use regular expression based matching for the condition or a custom function, say, on the 'key' value.


4. Interacting with mysql. I use mysql2 gem. Check out the documentation, it is pretty self-evident.

5. Working with Apache SOLR: rsolr and rsolr-ext are invaluable here:

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1. require 'rsolr'  
2. require 'rsolr-ext'  
3. solrServer = RSolr::Ext.connect :url => $solrServerUrl, :read_timeout => $read_timeout, :open_timeout => $open_timeout  
4.   
5. doc = {field1=>"value1", "field2"=>"value2"}  
6.   
7. solrServer.add doc  
8.   
9. solrServer.commit(:commit_attributes => {:waitSearcher=>false, :softCommit=>false, :expungeDeletes=>true})  
10. solrServer.optimize(:optimize_attributes => {:maxSegments=>1}) # single segment as output  

require 'rsolr'
require 'rsolr-ext'
solrServer = RSolr::Ext.connect :url => $solrServerUrl, :read_timeout => $read_timeout, :open_timeout => $open_timeout

doc = {field1=>"value1", "field2"=>"value2"}

solrServer.add doc

solrServer.commit(:commit_attributes => {:waitSearcher=>false, :softCommit=>false, :expungeDeletes=>true})
solrServer.optimize(:optimize_attributes => {:maxSegments=>1}) # single segment as output