Module: Schema::ClassMethods

Defined in:
lib/taco/schema.rb

Instance Method Summary collapse

Instance Method Details

#schema_attr(name, opts) ⇒ Object

Raises:

  • (TypeError) 


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# File 'lib/taco/schema.rb', line 85

def schema_attr(name, opts)
  @schema_attrs ||= {}

  raise TypeError.new("attribute #{name}: missing or invalid :class") unless opts[:class].is_a?(Class)

  if opts[:default].nil?
    opts[:default] = case opts[:class].to_s # can't case on opts[:class], because class of opts[:class] is always Class :-)
    when 'String'
      ''
    when 'Fixnum'
      0
    when 'Time'
      lambda { Time.new }
    else
      raise ArgumentError.new("Sorry, no default default exists for #{opts[:class]}")
    end
  end

  unless opts[:default].is_a?(opts[:class]) || opts[:default].is_a?(Proc)
    raise TypeError.new("attribute #{name}: invalid :default")
  end

  if opts[:validate]
    unless opts[:validate].is_a?(Array) || opts[:validate].is_a?(Proc)
      raise ArgumentError.new("attribute #{name}: expecting Array or Proc for :validate")
    end

    if opts[:validate].is_a?(Array)
      raise TypeError.new("attribute #{name}: wrong type in :validate Array") unless opts[:validate].all? { |v| v.is_a?(opts[:class]) }
    end
  end

  raise ArgumentError.new("attribute #{name}: already exists") if @schema_attrs[name]

  @schema_attrs[name] = opts

  value_getter = if opts[:default].is_a?(Proc)
    %Q(
        opts = self.class.schema_attributes[:#{name}]
        value = opts[:default].call
        raise TypeError.new("attribute #{name}: expected type #{opts[:class]}, received \#{value.class}") unless opts[:class] == value.class
    )
  else
    %Q(value = #{opts[:default].inspect})
  end
  module_eval %Q(
                  def #{name}
                    if @#{name}.nil?
                      #{value_getter}
                      self.#{name}= value
                    end
                    @#{name}
                  end
                )

  unless opts[:coerce] == false # possible values are false=no-coerce, nil=default-coerce, Proc=custom-coerce
    case opts[:class].to_s # can't case on opts[:class], because class of opts[:class] is always Class :-)
    when 'Fixnum'
      unless opts[:coerce].is_a? Proc
        # the default coercion for Fixnum
        opts[:coerce] = lambda do |value|
          unless value.is_a?(Fixnum) # FIXME: this "unless value.is_a?(same class as 'when')" is copy-pasta.  fix it.
            raise TypeError.new("attribute #{name}: cannot coerce from \#{value.class}") unless value.is_a?(String)
            i = value.to_i
            raise TypeError.new("attribute #{name}: failed to coerce from \#{value}") unless i.to_s == value
            value = i
          end
          value
        end
      end
    when 'Time'
      unless opts[:coerce].is_a? Proc
        # the default coercion for Time
        opts[:coerce] = lambda do |value|
          unless value.is_a?(Time) # FIXME: this "unless value.is_a?(same class as 'when')" is copy-pasta.  fix it.
            raise TypeError.new("attribute #{name}: cannot coerce from \#{value.class}") unless value.is_a?(String)
            begin
              value = Time.parse(value)
            rescue ArgumentError
              raise TypeError.new("attribute #{name}: cannot coerce from \#{value.class}")
            end
          end
          value
        end
      end
    end

    coerce = 'value = opts[:coerce].call(value)' if opts[:coerce]
  end

  unless opts[:transform] == false # possible values are false=no-transform, nil=default-transform, Proc=custom-transform
    case opts[:class].to_s # can't case on opts[:class], because class of opts[:class] is always Class :-)
    when 'String'
      unless opts[:transform].is_a? Proc
        # the default transform for String: remove excess whitespace
        opts[:transform] = lambda { |s| s.strip }
      end
    when 'Time'
      unless opts[:transform].is_a? Proc
        # the default transform for Time: remove subsecond precision.  subsec precision is not recorded in to_s, so unless
        #                                 we scrub it out, the following happens:
        #                                 foo.a_time = Time.new
        #                                 Time.parse(foo.a_time.to_s) == foo.a_time # returns false most of the time!
        opts[:transform] = lambda { |t| Time.new t.year, t.mon, t.day, t.hour, t.min, t.sec, t.utc_offset }
      end
    end

    transform = 'value = opts[:transform].call(value)' if opts[:transform]
  end

  callback = %Q(
    if self.respond_to? :schema_attribute_change
      self.schema_attribute_change(:#{name}, @#{name}, value)
    end
  )

  setter_method = %Q(
    def #{name}=(value)
      opts = self.class.schema_attributes[:#{name}]
      #{coerce}
      raise TypeError.new("attribute #{name}: expected type #{opts[:class]}, received \#{value.class}") unless opts[:class] == value.class
      #{transform}
      #{callback}
      @#{name} = value
    end
  )
  module_eval setter_method
  module_eval "private :#{name}=" unless opts[:settable]
end

#schema_attr_expand(prefix) ⇒ Object

Raises:

  • (KeyError) 


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# File 'lib/taco/schema.rb', line 59

def schema_attr_expand(prefix)
  candidates = @schema_attrs.keys.select { |a| a.to_s.start_with? prefix }
  raise KeyError.new("no attribute is prefixed with #{prefix}") if candidates.size == 0
  raise KeyError.new("prefix #{prefix} is not unique") if candidates.size > 1
  candidates[0]
end

#schema_attr_remove(name) ⇒ Object

Raises:

  • (KeyError) 


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# File 'lib/taco/schema.rb', line 66

def schema_attr_remove(name)
  raise KeyError.new("attribute #{name}: does not exist in class #{self.name}") unless @schema_attrs.include? name
  @schema_attrs.delete(name)
  self.send(:remove_method, name)
  self.send(:remove_method, "#{name}=".to_s)
end

#schema_attr_replace(name, opts) ⇒ Object

Raises:

  • (KeyError) 


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# File 'lib/taco/schema.rb', line 73

def schema_attr_replace(name, opts)
  raise KeyError.new("attribute #{name}: does not exist in class #{self.name}") unless @schema_attrs.include? name
  schema_attr_remove(name)
  schema_attr(name, opts)
end

#schema_attr_update(name, opts) ⇒ Object

Raises:

  • (KeyError) 


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# File 'lib/taco/schema.rb', line 79

def schema_attr_update(name, opts)
  raise KeyError.new("attribute #{name}: does not exist in class #{self.name}") unless @schema_attrs.include? name
  raise KeyError.new("attribute #{name}: cannot update non-settable attribute") unless @schema_attrs[name][:settable]
  schema_attr_replace(name, @schema_attrs[name].merge(opts))
end

#schema_attributes ⇒ Object 



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# File 'lib/taco/schema.rb', line 55

def schema_attributes
  @schema_attrs
end