Module: DataTransformer

Defined in:
lib/data_transformer.rb,
lib/data_transformer/version.rb

Constant Summary collapse

VERSION = 
"1.0.0"

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.tracing ⇒ Object

enable debug tracing



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# File 'lib/data_transformer.rb', line 5

def tracing
  @tracing
end

Class Method Details

.all(collection, rules) ⇒ Object

Transforms collection of objects according to rules. See rule examples in docs for DataTransformer#one



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# File 'lib/data_transformer.rb', line 32

def all(collection, rules)
  collection.map{|x| one(x, rules)}
end

.apply_rule(obj, rule) ⇒ Object 



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# File 'lib/data_transformer.rb', line 36

def apply_rule(obj, rule)
  apply_rules obj, Array(rule)
end

.apply_rules(object, rules) ⇒ Object 



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# File 'lib/data_transformer.rb', line 40

def apply_rules(object, rules)
  rules.reduce(object) do |obj, rule|
    p [obj, rule] if tracing
    case rule
    when Array
      obj.map{|x| apply_rules(x, rule)}
    when Symbol
      obj.send(rule)
    when Proc
      rule.(obj)
    when Hash
      rule.reduce({}) do |result, (k,v)|
        result.merge({k => apply_rule(obj, v)})
      end
    else
      raise ArgumentError, 'Only Symbol, Proc and Array or Hash of above are supported.'
    end
  end
end

.one(obj, rules) ⇒ Object

Transform Object to Hash according to rules. Rules is an array of elements of following type :foo => x.foo :bar => x.bar [:bar] => x.map(&:bar) [:bar :baz] => x.bar.baz [:bar [:baz]] => x.bar.map(&:baz) [:bar [:baz :quux]] => x.bar.map{|y| y.baz.quux}



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# File 'lib/data_transformer.rb', line 15

def one(obj, rules)
  rules.reduce({}) do |results,rule|
    case rule
    when Symbol
      results.merge(rule => apply_rule(obj, rule))
    when Hash
      ((key, value),) = rule.to_a
      results.merge(key => apply_rule(obj, value))
    else
      raise ArgumentError,
        'Only Symbol and Hash (with Symbols or Arrays) are supported as toplevel rules.'
    end
  end
end