Class: Rocknab::Builder

Inherits:
Object
  • Object
show all
Defined in:
lib/rocknab/builder.rb

Overview

This is the DSL that is used to declare CNAB registers

Declaration:

class MyRegister < Rocknab::Builder
  text :txt_field, length: 4
  number :num_field, length: 2
end

To use the class:

register = MyRegister.new(txt_field: "text", num_field: 10)
register.build
=> "TEXT10"

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(**args) ⇒ Builder

Subclasses can be initialized with the arguments passed as a hash, just like a Struct.

Usage:

MyRegister.new(txt_field: "text", num_field: 10)



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# File 'lib/rocknab/builder.rb', line 28

def initialize(**args)
  args.each do |key, value|
    instance_variable_set("@#{key}", value)
  end
end

Class Method Details

.date(name, length: 14, default: 0, padding: 0) ⇒ Object

Declares that the generated content has a date field. The format is DDMMYYYYhhmmss.

Parameters:

- name: Name of the field accessors
- length: Fixed length of the field. Default is 14.
- default: Default value. Zeroes if not specified.
- padding: Padding character. Zeros, if not specified.

Tip: Use 10 as the length, if you only need the date.

Usage:

class MyRegister < Rocknab::Builder
  date :created_at, length: 14, default: "hello", padding: " "
end



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# File 'lib/rocknab/builder.rb', line 99

def self.date(name, length: 14, default: 0, padding: 0)
  metadata << Builders::Date.new(name, length, default, padding)
  attr_accessor(name)
end

.inherited(child) ⇒ Object 



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# File 'lib/rocknab/builder.rb', line 129

def self.inherited(child)
  child.instance_eval do
    class << self
      attr_accessor :metadata
    end
  end

  child.metadata = []
end

.length ⇒ Object

Returns the total length of the fields. Useful for validation purposes and testing.

Usage:

MyRegister.length
=> 240



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# File 'lib/rocknab/builder.rb', line 125

def self.length
  metadata.map(&:length).reduce(&:+)
end

.number(name, length: 1, default: 0, padding: 0) ⇒ Object

Declares that the generated content has a numeric field. This field should only be used for integers.

Parameters:

- name: Name of the field accessors
- length: Fixed length of the field
- default: Default value. Zero if not specified.
- padding: Padding character. Zeros, if not specified.

Usage:

class MyRegister < Rocknab::Builder
  number :my_num, length: 20, default: 1234, padding: 0
end



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# File 'lib/rocknab/builder.rb', line 78

def self.number(name, length: 1, default: 0, padding: 0)
  metadata << Builders::Number.new(name, length, default, padding)
  attr_accessor(name)
end

.padding(length: 1, char: " ") ⇒ Object

Declares that the generated content has a padding

Parameters:

- length: Fixed length of the field
- char: Character that will be used to pad the content.
        The default is whitespace.

Usage:

padding length: 10, char: "0"



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# File 'lib/rocknab/builder.rb', line 114

def self.padding(length: 1, char: " ")
  metadata << Builders::Padding.new(length, char)
end

.text(name, length: 1, default: " ", padding: " ") ⇒ Object

Declares that the generated content has a text field

Parameters:

- name: Name of the field accessors
- length: Fixed length of the field
- default: Default value. Empty if not specified.
- padding: Padding character. Whitespace, if not specified.

Usage:

class MyRegister < Rocknab::Builder
  text :my_field, length: 20, default: "hello", padding: " "
end



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# File 'lib/rocknab/builder.rb', line 59

def self.text(name, length: 1, default: " ", padding: " ")
  metadata << Builders::Text.new(name, length, default, padding)
  attr_accessor(name)
end

Instance Method Details

#build ⇒ Object

Builds the class according to the definition

Usage:

register.build
=> "TEXT10"



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# File 'lib/rocknab/builder.rb', line 40

def build
  self.class.metadata.map do |field|
    field.build(self)
  end.join
end