Perform a Rails find() and iterate over the resulting records in groups

mcmire () — Mon, 05 May 2008 15:35:43 GMT



module ActiveRecord

  class Base

    # This method lets you iterate over the results of a .find, in groups.

    # (Basically an interface to LIMIT.)

    # Anything you can pass as options to .find, you can pass here. 

    # Example 1:

    #   Order.each_by(100, :conditions => { :cc_processed_at => nil }) do |order|

    #     # do stuff with order

    #   end

    # Example 2:

    #   Person.each_by(50, :order => 'name') do |person, index|

    #     # do stuff with person and index

    #   end

    # Pass :update => true in the options to print a message before each group is

    # fetched from the db.

    #

    # Author: Elliot Winkler 

    # Source: http://snippets.dzone.com/posts/show/5461

    def self.each_by(group_size, options={}, &blk)

      update = options.delete(:update) || false

      num_records = count(options.except(:from))

      return 0 if num_records == 0

      #raise "Number of records: #{num_records}"

      also_pass_offset = (blk.arity == 2)

      0.step(num_records, group_size) do |offset|

        find_options = { :offset => offset, :limit => group_size }.merge(options)

        if update

          if num_records == 1

            puts ">> Reading the only record."

          else

            start_offset = offset + 1

            end_offset   = offset + group_size

            end_offset   = num_records if num_records < end_offset

            puts ">> Reading records #{start_offset}-#{end_offset}."

          end

        end 

        find(:all, find_options).each do |record|

          also_pass_offset ? blk.call(record, offset) : blk.call(record)

        end

      end

      num_records

    end

  end

end

howmany

mcmire () — Tue, 11 Mar 2008 14:57:12 GMT



#!/usr/bin/perl

#==========================================================================================

# howmany -- a tool for determining how many different types of files are in a folder

#------------------------------------------------------------------------------------------

# Author: Elliot Winkler 

# Created: 11 Mar 2008

#==========================================================================================



my $dir = $ARGV[0] || ".";

my $cmd = "find $dir";

my @listing = sort grep { $_ } split /\n/, `$cmd`;



my %exts;

for (@listing) {

  my($ext) = /\.([a-z]+)$/;

  next unless $ext;

  $exts{lc $ext}++;

}



for (sort keys %exts) {

  print uc($_).": ".$exts{$_}."\n";

}

Example:


$ cd ~/docs

$ howmany

CSV: 3

DOC: 1

KEY: 1

PUB: 1

SQL: 1

TEXT: 1

TXT: 9

XCF: 2

XLS: 1

ZIP: 1

$ howmany ~/docs

CSV: 3

DOC: 1

KEY: 1

PUB: 1

SQL: 1

TEXT: 1

TXT: 9

XCF: 2

XLS: 1

ZIP: 1

Note: This only works on Linux/Unix, because it relies on a Linux/Unix-only command to pull up the list of files. A future update may include support for Windows, though it would be pretty easy to find out how to fix it.

DZone Snippets: Mcmire's Code Snippets

Perform a Rails find() and iterate over the resulting records in groups

howmany