Friday, November 14, 2014

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:

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

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

2. Command line options parsing:

require 'optparse'
class Optparser

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

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

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

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



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:

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:

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

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