Class: Arrow::Field

Inherits:
Object
  • Object
show all
Defined in:
lib/arrow/field.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, data_type, nullable = false) ⇒ Field #initialize(description) ⇒ Field

Creates a new Arrow::Field.

Overloads:

  • #initialize(name, data_type, nullable = false) ⇒ Field

    Examples:

    Create a field with DataTypes

    Arrow::Field.new("visible", Arrow::BooleanDataType.new)

    Create a field with data type description

    Arrow::Field.new("visible", :boolean)

    Create a field with name as ‘Symbol`

    Arrow::Field.new(:visible, :boolean)

    Parameters:

    • name (String, Symbol) —

      The name of the field.

    • data_type (Arrow::DataType, Hash, String, Symbol) —

      The data type of the field.

      You can specify data type as a description by ‘Hash`.

      See DataType.resolve how to specify data type description.

    • nullable (Boolean, nil) (defaults to: false) —

      (false) Whether the field may contain zero or more nulls.

      ‘nil` is processed as `true` (null may be contained).

  • #initialize(description) ⇒ Field

    Examples:

    Create a field with DataTypes

    Arrow::Field.new(name: "visible",
                 data_type: Arrow::BooleanDataType.new)

    Create a field with data type description

    Arrow::Field.new(name: "visible", data_type: {type: :boolean}

    Create a field with shortcut form

    Arrow::Field.new(name: "visible", type: :boolean)

    Parameters:

    • description (Hash) —

      The description of the field.

      Field description is a raw ‘Hash`. Field description must have `:name` and `:data_type` values. `:name` is the name of the field. `:data_type` is the data type of the field. You can use DataType or data type description as `:data_type` value.

      See DataType.resolve how to specify data type description.

      There is a shortcut for convenience. If field description doesn’t have ‘:data_type`, all keys except `:name` are processes as data type description. For example, the following field descriptions are the same:

      “‘ruby “visible”, data_type: {type: :boolean} “visible”, type: :boolean # Shortcut version “`

    Options Hash (description):

    • :name (String, Symbol) —

      The name of the field.

    • :data_type (Arrow::DataType, Hash) —

      The data type of the field. You can specify data type description by ‘Hash`.

      See DataType.resolve how to specify data type description.

    • :nullable (Boolean, nil) —

      Whether the field may contain zero or more nulls.

      ‘nil` is processed as `true` (null may be contained).



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# File 'lib/arrow/field.rb', line 113

def initialize(*args)
  n_args = args.size
  case n_args
  when 1
    description = args[0]
    name = nil
    data_type = nil
    data_type_description = {}
    nullable = nil
    description.each do |key, value|
      key = key.to_sym
      case key
      when :name
        name = value
      when :data_type
        data_type = DataType.resolve(value)
      when :nullable
        nullable = value
      else
        data_type_description[key] = value
      end
    end
    data_type ||= DataType.resolve(data_type_description)
  when 2
    name = args[0]
    data_type = args[1]
    if data_type.is_a?(Hash)
      data_type = data_type.dup
      nullable = data_type.delete(:nullable)
    else
      nullable = nil
    end
    data_type = DataType.resolve(data_type)
  when 3
    name = args[0]
    data_type = DataType.resolve(args[1])
    nullable = args[2]
  else
    message = "wrong number of arguments (given #{n_args}, expected 1..3)"
    raise ArgumentError, message
  end
  nullable = true if nullable.nil?

  initialize_raw(name, data_type, nullable)
end

Class Method Details

.try_convert(value) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/arrow/field.rb', line 22

def try_convert(value)
  case value
  when Hash
    begin
      new(value)
    rescue ArgumentError
      nil
    end
  else
    nil
  end
end