Module: Fend::Plugins::DataProcessing

Defined in:
lib/fend/plugins/data_processing.rb

Overview

By default, Fend provides methods for input and output processing.

class UserValidation < Fend
  #...

  def process_input(input)
    # symbolize input data keys
    symbolized_input = input.each_with_object({}) do |(key, value), result|
      new_key = key.is_a?(String) ? key.to_sym : key
      result[new_key] = value
    end

    # do some additional processing
  end

  def process_output(output)
    # filter output data
    whitelist = [:username, :email, :address]
    filtered_output = output.each_with_object({}) do |(key, value), result|
      result[key] = value if whitelist.include?(key)
    end

    # do some additional processing
  end
end

‘data_processing` plugin allows you to define processing steps in more

declarative manner:

   plugin :data_processing

   process(:input) do |input|
     # symbolize keys
   end

   process(:output) do |output|
     # filter
   end

You can define as much processing steps as you need and they will be executed in order in which they are defined.

## Built-in processings

You can activate built-in processings when loading the plugin:

# this will:
#   symbolize and freeze input data
#   stringify output data
plugin :data_processing, input: [:symbolize, :freeze],
                         output: [:stringify]

:symbolize : Symbolizes keys.

:stringify : Stringifies keys

:dup : Duplicates data

:freeze : Freezes data

All of the above support deeply nested data.

Built-in processings are executed before any user-defined ones.

## Data mutation

Fend will never mutate the raw input data you provide:

raw_input = { username: "john", email: "john@example.com" }
UserValidation.call(raw_input)

However, nothing can stop you from performing destructive operations (‘merge!`, `delete`, etc…) in custom processing steps. If you intend to mutate input/output data, make sure to use `:dup` processing, in order to ensure immutability.

Defined Under Namespace

Modules: ClassMethods, InstanceMethods Classes: Process

Constant Summary collapse

BUILT_IN_PROCESSINGS = 
{
  symbolize:   ->(data) { Process.symbolize_keys(data) },
  stringify:   ->(data) { Process.stringify_keys(data) },
  dup:         ->(data) { Process.duplicate(data) },
  freeze:      ->(data) { Process.frost(data) }
}.freeze

Class Method Summary collapse

Class Method Details

.configure(validation, options = {}) ⇒ Object

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# File 'lib/fend/plugins/data_processing.rb', line 93

def self.configure(validation, options = {})
  validation.opts[:data_processing] = {}
  validation.opts[:data_processing][:input] ||= []
  validation.opts[:data_processing][:output] ||= []

  return if options.empty?

  options.each do |data_ref, processings|
    processings.each_with_object(validation.opts[:data_processing][data_ref]) do |name, result|
      raise Error, "Built-in processing not found: ':#{name}'" unless BUILT_IN_PROCESSINGS.key?(name)

      result << BUILT_IN_PROCESSINGS[name]
    end
  end
end