Class: Rack::Reducer::Reduction

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/reducer/reduction.rb

Overview

call ‘reduce` on a params hash, filtering data via lambdas with matching keyword arguments

Instance Method Summary collapse

Constructor Details

#initialize(dataset, *filters) ⇒ Reduction

Returns a new instance of Reduction.



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# File 'lib/rack/reducer/reduction.rb', line 12

def initialize(dataset, *filters)
  @dataset = dataset
  @filters = filters
  @default_filters = filters.select do |filter|
    filter.required_argument_names.empty?
  end
end

Instance Method Details

#apply(params) ⇒ Object

Run @filters against the params argument

Parameters:

  • params (Hash, ActionController::Parameters, nil) —

    a Rack-compatible params hash

Returns:

  • @dataset with the matching filters applied



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# File 'lib/rack/reducer/reduction.rb', line 24

def apply(params)
  if !params || params.empty?
    return @dataset if @default_filters.empty?

    filters = @default_filters
    symbolized_params = {}
  else
    filters = @filters
    symbolized_params = params.to_unsafe_h.symbolize_keys
  end

  filters.reduce(@dataset) do |data, filter|
    next data unless filter.satisfies?(symbolized_params)

    data.instance_exec(
      **symbolized_params.slice(*filter.all_argument_names),
      &filter
    )
  end
end