Module: IknowParams::Parser

Extended by:
ActiveSupport::Concern
Included in:
HashParser
Defined in:
lib/iknow_params/parser.rb

Overview

IknowParams::Parser provides a mix-in for ActiveRecord controllers to parse input parameters.

Defined Under Namespace

Classes: HashParser, ParseError

Constant Summary collapse

PARAM_REQUIRED = 
Object.new
BLANK = 
Object.new

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.parse_hash(hash, &block) ⇒ Object 



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# File 'lib/iknow_params/parser.rb', line 27

def parse_hash(hash, &block)
  HashParser.new(hash).parse(&block)
end

.parse_value(value, **args) ⇒ Object 



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# File 'lib/iknow_params/parser.rb', line 31

def parse_value(value, **args)
  HashParser.new({ sentinel: value }).parse_param(:sentinel, **args)
end

.parse_values(values, **args) ⇒ Object 



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# File 'lib/iknow_params/parser.rb', line 35

def parse_values(values, **args)
  HashParser.new({ sentinel: values }).parse_array_param(:sentinel, **args)
end

.register_serializer(name, serializer) ⇒ Object

Allow serializers to register themselves



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# File 'lib/iknow_params/parser.rb', line 146

def self.register_serializer(name, serializer)
  define_method(:"parse_#{name.underscore}_param") do |param, default: PARAM_REQUIRED|
    parse_param(param, with: serializer, default: default)
  end
  define_method(:"parse_#{name.underscore}_array_param") do |param, default: PARAM_REQUIRED|
    parse_array_param(param, with: serializer, default: default)
  end
end

Instance Method Details

#parse_array_param(param, with: nil, default: PARAM_REQUIRED, dump: false) ⇒ Object

Parse an array-typed param using the provided serializer for each member element.



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# File 'lib/iknow_params/parser.rb', line 89

def parse_array_param(param, with: nil, default: PARAM_REQUIRED, dump: false)
  serializer =
    case with
    when String, Symbol
      IknowParams::Serializer.for!(with)
    else
      with
    end

  vals = params[param]

  parses =
    if vals.nil?
      raise ParseError.new("Required parameter '#{param}' missing", param, nil) if default == PARAM_REQUIRED
      default
    elsif !vals.is_a?(Array)
      raise ParseError.new("Invalid type for parameter '#{param}': '#{vals.class.name}'", param, vals)
    elsif serializer.present?
      vals.map do |val|
        begin
          serializer.load(val)
        rescue IknowParams::Serializer::LoadError => ex
          raise ParseError.new("Invalid member in array parameter '#{param}': '#{val.inspect}' - #{ex.message}", param, val)
        end
      end
    else
      vals
    end

  if dump && parses != BLANK
    parses.map! { |v| serializer.dump(v) }
  end

  parses
end

#parse_param(param, with: nil, default: PARAM_REQUIRED, dump: false) ⇒ Object

Parse the specified parameter, optionally deserializing with the provided IKnowParams::Serializer. If the parameter is missing and no default is provided, raises a ParseError.

If BLANK is provided as a default, return a placeholder object that can be later stripped out with remove_blanks

If dump is true, use the serializer to re-serialize any successfully parsed argument back to a canonical string. This can be useful to validate and normalize the input to another service without parsing it. A serializer must be passed to use this option.



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# File 'lib/iknow_params/parser.rb', line 51

def parse_param(param, with: nil, default: PARAM_REQUIRED, dump: false)
  serializer =
    case with
    when String, Symbol
      IknowParams::Serializer.for!(with)
    else
      with
    end

  parse =
    if !params.has_key?(param)
      raise ParseError.new("Required parameter '#{param}' missing", param, nil) if default == PARAM_REQUIRED
      default
    else
      val = params[param]
      if serializer.present?
        begin
          serializer.load(val)
        rescue IknowParams::Serializer::LoadError => ex
          raise ParseError.new("Invalid parameter '#{param}': '#{val.inspect}' - #{ex.message}", param, val)
        end
      else
        val
      end
    end

  if dump && parse != BLANK
    begin
      parse = serializer.dump(parse)
    rescue NoMethodError => ex
      raise ParseError.new("Serializer '#{serializer}' can't dump param '#{param}' #{val.inspect} - #{ex.message}", param, val)
    end
  end

  parse
end

#remove_blanks(arg) ⇒ Object

Convenience method to make it simpler to build a hash structure with optional members from parsed data. This method recursively traverses the provided structure and removes any instances of the sentinel value Parser::BLANK.



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# File 'lib/iknow_params/parser.rb', line 129

def remove_blanks(arg)
  case arg
  when Hash
    arg.each do |k, v|
      if v == BLANK
        arg.delete(k)
      else
        remove_blanks(v)
      end
    end
  when Array
    arg.delete(BLANK)
    arg.each { |e| remove_blanks(e) }
  end
end