Class: Formant::FormObject

Inherits:
Object
  • Object
show all
Includes:
ActiveModel::Model, ActiveModel::Validations::Callbacks
Defined in:
lib/formant.rb

Overview

Base class for Form objects.

See www.reinteractive.net/posts/158-form-objects-in-rails (among others) for more info on form objects for more details.

This is a simplified implementation of form objects that focuses on collecting input in a PORO, specifying any special parsing and transformation on fields upon input (i.e., before validation), and special formatting/transformation on fields for display/output and redisplay of forms.

Class Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Class Attribute Details

.format_fields ⇒ Object

Returns the value of attribute format_fields.



32
33
34
 
# File 'lib/formant.rb', line 32

def format_fields
  @format_fields
end

.parse_fields ⇒ Object

Returns the value of attribute parse_fields.



32
33
34
 
# File 'lib/formant.rb', line 32

def parse_fields
  @parse_fields
end

Class Method Details

.parse(field_name, options = {}) ⇒ Object

Directive to add a parse rule for the specified attribute. Parse rules let you apply any special parsing/transformation logic on the form’s attributes upon input. The parsing rules are applied automatically prior to validation.

Usage example:

class MyForm < FormObject

...
parse :appointment_time, as: :datetime
parse :phone, as: :phone_number
parse :price, as: :currency
parse :email, to: :strip_whitespace
...

end

The above example specifies that the appointment_time attribute should be parsed with the parse_datetime method (which converts the datetime string into an ActiveSupport::TimeWithZone object), and that the # phone attribute should be parsed with the parse_phone_number method (which normalizes the phone number into a standard format).



59
60
61
62
63
64
 
# File 'lib/formant.rb', line 59

def self.parse(field_name, options={})
  self.parse_fields ||= []
  parse_type = options[:as] || options[:to]
  raise "no parse type provided" if parse_type.blank?
  self.parse_fields << [ field_name, "parse_#{parse_type}", options ]
end

.reformat(field_name, options = {}) ⇒ Object

Directive to add a reformat rule for the specified attribute. These let you apply any special formatting/normalization logic on the form’s attributes upon output. Typically you want to do this when you have to redisplay a form.

The format rules are triggered when the FormObject#reformatted! method is invoked, which modifies the attribute in place.

Usage example:

class MyForm < FormObject

...
reformat :appointment_time, as: :datetime, format: :day_date_time
reformat :phone, as: :phone_number, country_code: 'US'
...

end

The above example specifies that the appointment_time attribute should be reformatted with the format_datetime method (using the format specified in the locale file with the :day_date_time key), and that the phone attribute should be parsed with the parse_phone_number method, and a fixed country_code of ‘US’



90
91
92
93
 
# File 'lib/formant.rb', line 90

def self.reformat(field_name, options={})
  self.format_fields ||= []
  self.format_fields << [ field_name, "format_#{options[:as]}", options ]
end

Instance Method Details

#reformatted! ⇒ Object

Triger any formatting rules specified with the reformat directive. The attributes are reformatted and mutated in place.

Returns an instance of the form object.



101
102
103
104
105
106
107
 
# File 'lib/formant.rb', line 101

def reformatted!
  self.class.format_fields.each do |field_name, format_method, options|
    formatted_value = send(format_method, get_field(field_name), options)
    set_field(field_name, formatted_value)
  end
  self
end

#to_params ⇒ Object

Return all the attributes as a params hash.



112
113
114
115
116
117
118
119
 
# File 'lib/formant.rb', line 112

def to_params
  attrs = Hash.new
  instance_variables.each do |ivar|
    name = ivar[1..-1]
    attrs[name.to_sym] = instance_variable_get(ivar) if respond_to? "#{name}="
  end
  attrs
end