This gem was built for create text files based in fixed columns.
gem install typecaster
The Typecaster can be used for two things. To create text files based on positions and read text files based on some descriptor.
Given you need generate a text with the following format:
column name | size | starting | ending | type |
name | 10 | 0 | 9 | string |
price | 8 | 10 | 17 | number |
code | 6 | 18 | 23 | string |
Here's how to use it:
module StringTypecaster
def self.call(value, options)
value.to_s.ljust(options[:size], " ")
end
end
module NumerTypecaster
def self.call(value, options)
value.to_s.rjust(options[:size], "0")
end
end
class ProductFormatter
include Typecaster
attribute :code, :size => 6, :position => 3, :caster => StringTypecaster
attribute :name, :size => 10, :position => 1, :caster => StringTypecaster
attribute :price, :size => 8, :position => 2, :caster => NumberTypecaster
end
product = ProductFormatter.new(:name => 'Coca', :price => '25.0', :code => '6312')
puts product.to_s # => 'Coca 000025.06312 'And you also can group the attributes with common options using with_options method passing a block
class ProductFormatter
include Typecaster
with_options :caster => StringTypecaster do
attribute :code, :size => 6, :position => 2
attribute :name, :size => 10, :position => 1
end
attribute :price, :size => 8, :position => 3, :caster => NumberTypecaster
endYou can parse a collection with values. This collection can be any object that responds to []. (Hash and ActiveRecord objects are more common). See:
module StringTypecaster
def self.call(value, options)
value.to_s.ljust(options[:size], " ")
end
end
module NumerTypecaster
def self.call(value, options)
value.to_s.rjust(options[:size], "0")
end
end
class ProductFormatter
include Typecaster
output_separator ";"
attribute :code, :size => 6, :position => 3, :caster => StringTypecaster
attribute :name, :size => 10, :position => 1, :caster => StringTypecaster
attribute :price, :size => 8, :position => 2, :caster => NumberTypecaster
end
product = ProductFormatter.new([{:name => 'Coca', :price => '25.0', :code => '6312'}, {:name => 'Coca', :price => '25.0', :code => '6312'}])
puts product.to_s # => 'Coca ;000025.0;6312 \nCoca ;000025.0;6312 'You can change the output separator
module StringTypecaster
def self.call(value, options)
value.to_s.ljust(options[:size], " ")
end
end
module NumerTypecaster
def self.call(value, options)
value.to_s.rjust(options[:size], "0")
end
end
class ProductFormatter
include Typecaster
output_separator ";"
attribute :code, :size => 6, :position => 3, :caster => StringTypecaster
attribute :name, :size => 10, :position => 1, :caster => StringTypecaster
attribute :price, :size => 8, :position => 2, :caster => NumberTypecaster
end
product = ProductFormatter.new(:name => 'Coca', :price => '25.0', :code => '6312')
puts product.to_s # => 'Coca ;000025.0;6312 'Given a file with products like that:
Coca 000025.06312
Pepsi 000023.06313
module StringTypecaster
def self.call(value, options)
value.to_s.ljust(options[:size], " ")
end
end
module NumerTypecaster
def self.call(value, options)
value.to_s.rjust(options[:size], "0")
end
end
class ProductFormatter
include Typecaster
attribute :code, :size => 6, :position => 3, :caster => StringTypecaster
attribute :name, :size => 10, :position => 1, :caster => StringTypecaster
attribute :price, :size => 8, :position => 2, :caster => NumberTypecaster
end
products = ProductFormatter.parse_file(File.open('your_file_path', 'r'))
puts products.inspect # => [{:name => 'Coca', :price => '25.0', :code => '6312'}, {:name => 'Pepsi', :price => '23.0', :code => '6313'}]Given a file like that:
0SOME IMPORTANT TEXT 000001
119999FOO BAR 000002
110000XPTO BAR 000003
109901JOAO BAR 000004
939900 000005
Each row in that file was identified by a number 0 for header, 1 for the records inside and 9 for footer, each row has 27 chars, to read then you must implement the parsers for each row type.
module StringTypecaster
def self.parse(text)
text.strip
end
end
module IntegerTypecaster
def self.parse(text)
text.to_i
end
end
class MyFileHeader
include Typecaster
with_options :caster => StringTypecaster do
attribute :identifier, :size => 1, :position => 1
attribute :text, :size => 20, :position => 2
end
attribute :sequential, :size => 5, :position => 3, :caster => IntegerTypecaster
end
class MyFileRow
include Typecaster
with_options :caster => StringTypecaster do
attribute :identifier, :size => 1, :position => 1
attribute :name, :size => 15, :position => 3
end
with_options :caster => IntegerTypecaster, :size => 5 do
attribute :amount, :position => 2
attribute :sequential, :position => 4
end
end
class MyFileFooter
include Typecaster
with_options :caster => StringTypecaster do
attribute :identifier, :size => 1, :position => 1
attribute :blanks, :size => 15, :position => 3
end
with_options :caster => IntegerTypecaster do
attribute :total, :size => 5, :position => 2
attribute :sequential, :size => 6, :position => 4
end
end
class MyFileParser
include Typecaster::Parse
parser :header, :with => MyFileHeader, :identifier => '0'
parser :rows, :with => MyFileRow, :identifier => '1', :array => true
parser :footer, :with => MyFileFooter, :identifier => '9'
end
MyFileParser.parse(File.new('my_file.txt'))Its results in a hash, with keys the following keys: header, rows and footer. The key 'rows' will be an array.
- Fork the project.
- Make your feature addition or bug fix.
- Add tests for it.
- Commit, do not mess with rakefile, version, or history.
- Send me a pull request.
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