Examples of dependency injection using the u-case gem

01.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'u-case', '~> 4.2.1'
end

require 'json'

module ReportFormatters
  HTML = -> data { %[<ul>#{data.map { |product, amount| "<li>#{product}: #{amount}</li>" }.join}</ul>] }
  JSON = -> data { data.to_json }
  PlainText = -> data { data.to_s }
end

class FetchReportData < Micro::Case
  def call!
    Success result: { data: { onions: 31, potatoes: 24, eggs: 10 } }
  end
end

class GenerateReport < Micro::Case
  attributes :data, :formatter
  
  def call!
    return Failure() unless data || formatter

    Success result: { report: formatter.call(data) }
  end
end

FetchReportData
  .call
  .then(GenerateReport, formatter: ReportFormatters::HTML)
  .on_success { |result| p result[:report] }

02.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'u-case', '~> 4.2.1'
end

require 'json'

module ReportFormatters
  HTML = -> data { %[<ul>#{data.map { |product, amount| "<li>#{product}: #{amount}</li>" }.join}</ul>] }
  JSON = -> data { data.to_json }
end

class FetchReportData < Micro::Case
  def call!
    Success result: { data: { onions: 31, potatoes: 24, eggs: 10 } }
  end
end

class GenerateReport < Micro::Case
  attributes :data, :formatter
  
  def call!
    return Failure() unless data || formatter

    Success result: { report: formatter.call(data) }
  end
end

GenerateReportAsJSON = Micro::Cases.flow([
  FetchReportData,
  [GenerateReport, formatter: ReportFormatters::JSON]
])

GenerateReportAsJSON.call.on_success { |result| p result[:report] }

03.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'u-case', '~> 4.2.1'
end

require 'json'

module ReportFormatters
  HTML = -> data { %[<ul>#{data.map { |product, amount| "<li>#{product}: #{amount}</li>" }.join}</ul>] }
  JSON = -> data { data.to_json }
end

class GenerateReport < Micro::Case
  attributes :data, :formatter
  
  def call!
    return Failure() unless data || formatter

    Success result: { report: formatter.call(data) }
  end
end

class GenerateReportAsHTML < Micro::Case
  attribute :data

  def call!
    call(GenerateReport, formatter: ReportFormatters::HTML)
  end
end

GenerateReportAsHTML
  .call(data: { onions: 31, potatoes: 24, eggs: 10 })
  .on_success { |result| p result[:report] }