Class: JsonDataExtractor::Extractor

Inherits:
Object
  • Object
show all
Defined in:
lib/json_data_extractor/extractor.rb

Overview

does the main job of the gem

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(json_data, modifiers = {}) ⇒ Extractor

Returns a new instance of Extractor.

Parameters:

  • json_data (Hash, String)
  • modifiers (Hash) (defaults to: {}) 

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# File 'lib/json_data_extractor/extractor.rb', line 10

def initialize(json_data, modifiers = {})
  @data = json_data.is_a?(Hash) ? json_data.to_json : json_data
  @modifiers = modifiers.transform_keys(&:to_sym)
  @results = {}
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.


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# File 'lib/json_data_extractor/extractor.rb', line 6

def data
  @data
end

#modifiers ⇒ Object (readonly)

Returns the value of attribute modifiers.


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# File 'lib/json_data_extractor/extractor.rb', line 6

def modifiers
  @modifiers
end

Instance Method Details

#add_modifier(modifier_name, callable = nil, &block) ⇒ Object

Parameters:

  • modifier_name (String, Symbol)
  • callable (#call, nil) (defaults to: nil) —

    Optional callable object

Raises:

  • (ArgumentError) 

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# File 'lib/json_data_extractor/extractor.rb', line 18

def add_modifier(modifier_name, callable = nil, &block)
  modifier_name = modifier_name.to_sym unless modifier_name.is_a?(Symbol)
  modifiers[modifier_name] = callable || block

  return if modifiers[modifier_name].respond_to?(:call)

  raise ArgumentError, 'Modifier must be a callable object or a block'
end

#extract(schema) ⇒ Object

Parameters:

  • schema (Hash) —

    schema of the expected data mapping


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# File 'lib/json_data_extractor/extractor.rb', line 28

def extract(schema)
  schema.each do |key, val|
    element = JsonDataExtractor::SchemaElement.new(val.is_a?(Hash) ? val : { path: val })

    extracted_data = JsonPath.on(@data, element.path) if element.path

    if extracted_data.nil? || extracted_data.empty?
      # we either got nothing or the `path` was initially nil
      @results[key] = element.fetch_default_value
      next
    end

    # check for nils and apply defaults if applicable
    extracted_data.map! { |item| item.nil? ? element.fetch_default_value : item }

    # apply modifiers if present
    extracted_data = apply_modifiers(extracted_data, element.modifiers) if element.modifiers.any?

    # apply maps if present
    @results[key] = element.maps.any? ? apply_maps(extracted_data, element.maps) : extracted_data

    @results[key] = resolve_result_structure(@results[key], element)
  end

  @results
end