ReportLogic

This gem provides an easy way to generate reports' logic. You can organize the way your data needs to be grouped, converted and organized, regardless how you are going to display it afterwards. I use this to export the same report in various formats, like XLS and PDF, using the same Report object.

Installation

gem install report_logic

Using Bundler:

gem 'report_logic'

Usage

The goal here is to provide an easy way to extract report's logic to a Plain Old Ruby Object. The report is defined by doing this:

# Create a class inheriting from ReportLogic::Base
class MyReport < ReportLogic::Base

  # Create as many sessions as you need. Sessions group fields that you can
  # then display later.
  session :header do
    field 'ID'    # `field` creates a ReportLogic::Field in the session,
                  # which `name` will be the value passed to it.
    field 'Name'
  end

  # If you call `collection_session`, it will become a matrix, instead of
  # an array of Field. For each object in the collection given to the
  # constructor, the block will be yielded with it so you can define what Fields
  # will compose the matrix.
  collection_session :row do |record|
    value record.id     # `value` creates a ReportLogic::Field in the session,
                        # which `value` will be the value passed to it.
    value record.name
  end
end

And that's the basics. Now, to show this report:

report = MyReport.new(MyModel.all)

# Printing a title
puts 'MY REPORT'

# Printing the headers
report.header.each do |field|
  print field.name
  print ' | '
end
puts

# Printing the rows
report.row.each do |row|
  row.each do |field|
    print field.value
    print ' | '
  end
  puts
end

This output is not pretty, but it shows how simple it is to read a report and output it in any ways you want. You could use ERB to generate HTML or XLS outputs in Rails, or even Prawn to generate PDF's.

Decorators

This gem uses the Decorator Pattern to allow you to modify a Field before printing. To do so, pass the decorator as a parameter to the field. It can be any object, it just needs to respond to call. It can be a simple block.

class MyDecorator
  def call(name)
    "=> #{name}"
  end
end

class MyReport < ReportLogic::Base
  collection_session :row do |record|
    field 'Name', record.name, decorate_name: MyDecorator.new,
                               decorate_value: ->(value) { " - #{value}" }
  end
end

MyModel = Struct.new(:name)
collection = [MyModel.new('John')]

MyReport.new(collection).row.each do |row|
  row.each do |field|
    puts field.name
    puts field.value
  end
end
#=> => Name
#=>  - John

If you need to apply multiple decorators on the same field, just pass an array.

Contributing

Do you have an idea or a bug fix to add to the gem? Please do!

Fork it
Make your changes and commits
Create a pull request