[Cascade]

The main goal of this gem is to provide some kind of template for parsing files. Usually, file parsing process consists of the following steps:

1. Retrieve info from file
2. Distinguish content from each file line
3. Parse each column with corresponding parser
4. Generate some kind of data record
5. Save obtained record
6. Handle errors
7. Generate report

Cascade pretends to simplify main part of this step to save your time.

Install the cascade-rb package from Rubygems:

gem install cascade-rb

or add it to your Gemfile for Bundler:

gem 'cascade-rb'

Require gem files

require 'cascade'

Provide enumerable object for parsing and run it!

Cascade::DataParser.new(data_provider: Csv.open("data_test.csv")).call

Parsing file description should have the following structure (example)

mapping:
  name: type

There are already several defined field parsers (types):

• currency
• boolean
• string

Feel free to add new field parsers through PR.

There is a lot of DI in this gem, so, you can replace each component of the parser. Let's assume you want to parse JSON files instead of CSV, save this to ActiveRecord model, and you need Date fields parsing, ok! Writing new data provider:

class ParserJSON
  def open(file)
    JSON.parse(File.read(file))["rows"]
  end
end

Writing new data saver:

class PersonDataSaver
  def call(person_data)
    Person.create!(person_data)
  end
end

considering that there is no much logic even better

 PERSON_SAVER = -> (person_data) { Person.create!(person_data) }

Writing date parser:

class DateParser
  def call(value)
    Date.parse(value)
  end
end

or you can always use lambdas for such logic

DATE_PARSER = -> (value) { Date.parse(value) }

Provide all this stuff into data parser

Cascade::DataParser.new(
  data_provider: ParserJSON.new.open("data_test.csv"),
  row_processor: Cascade::RowProcessor.new(ext_parsers: { date: DateParser.new }),
  data_saver: PERSON_SAVER
 ).call

And that's all!