HungryForm

HungryForm is a gem for managing multipage forms. The main purpose of this gem is to give developers an easy DSL to build complex forms. Rails integration can be done via the hungryform-rails gem.

Usage

form = HungryForm::Form.new do
  page :first do
    text_field :first_name, required: true
    text_field :last_name, required: true
  end
  page :second do 
    text_field :address
    select_field :gender, options: { "M" => "Male", "F" => "Female" }, required: true
  end
  page :third do 
    text_field :occupation
    
    # Show this group only when the occupation field is not empty
    group :employment_history, dependency: { set: "third_occupation" } do
      html :before, value: "Employment history over the last 5 years"
      text_area :history, value: "Default value"
    end
  end 
end

if form.valid?
  form.to_json
end

Field Dependencies

Each element of HungryForm, including pages and groups, can have a dependency parameter. This parameter must be a hash, containing a tree of basic operations. The dependency tree eventually resolves into to a boolean result. Within this tree you can use and combine the following operators, creating complex dependencies that can involve multiple elements:

# val1 == val2
{ eq: ["val1", "val2"] }

# val1 > val2
{ gt: ["val1", "val2"] }

# val1 < val2
{ lt: ["val1", "val2"] }

# val1 is not empty
{ set: "val1" }

# Get the opposite result of the expression
{ not: { eq: [1, 1] } }

# Check if all the expressions are true
{ 
  and: [
    { eq: [1, 1] },
    { eq: [2, 2] }
  ] 
}

# Check if any of the expressions is true
{ 
  or: [
    { not: { eq: [1, 1] } },
    { eq: [2, 2] }
  ] 
}

If the dependency is resolved positively it makes the element visible. Otherwise the element will be hidden with all its validation rules omited. It is allowed to use element names or params keys as parameters inside expressions.

HungryForm::Form.new do
  page :about do
    text_field :age
    text_field :favourite_alcohol, required: true, dependency: { gt: ["about_age", 18] }
  end
end

Assigning values

To assign values to form fields pass them as a hash on form initialization. The params hash must consist of field names and their values. Please note, that the field names must contain the full path to the field, starting from the page name.

params = {
  "first_first_name" => "John",
  "first_last_name" => "Doe",
  "second_address" => "John's address",
  "third_occupation" => "Software engineer",
  "third_employment_history_history" => "John's employment history"
}

form = HungryForm::Form.new :params => params do
...
end

Assign a default value to a form field:

text_field :email, value: "john.doe@yahoo.com"

You can assign any attribute to the field and it will be included into the field attributes during rendering:

text_field :email, my_attribute: "attribute value"

Configuration

To configure the gem use the configuration block:

HungryForm.configure do |config|
  config.text_field maxlength: 100
end

text_field (or any other element name): Assign an attribute to all elements of this type

Validation

Each active element of a form can be assigned with validation rules.

required - accepts boolean or proc
validation - accepts proc

text_field :name, required: true
text_field :email, validation: ->(el) { "is unexpected email" unless el.value == "me@yahoo.com"  }

You can extend the list of validation rules by creating your own validation methods:

module HungryForm
  module Validator
    class << self
      def my_validation_method(element, rule)
        "is not #{rule}" unless element.value == rule
      end
    end
  end
end
  
  
text_field :vegetable, value: "tomato", my_validation_method: "potato" # => is not potato

Custom form fields

You can create your own field type by adding a new class into the HungryForm::Elements module. There are three base classes that you can choose to inherit from:

Base::Element - use this class when you don't need the field to have a value and validation. As an example it can be used for text/html output
Base::ActiveElement - use this class when you need the field to have a value and validation
Base::OptionsElement - this class inherits the Base::ActiveElement. Use it when you need to create an element with an options hash, like a dropdown

module HungryForm
  module Elements
    class MyField < Base::ActiveElement
      attr_accessor :my_param

      hashable :my_param
      
      def initialize(name, parent, resolver, options = {}, &block)
        self.my_param = options[:my_param] || true
        
        super
      end
      
      def valid?
        self.value == 'valid_value'
      end
    end
  end
end

form = HungryForm::Form.new do
  page :main do
    my_field :my_field_name, my_param: "Param Value"
  end
end

Contributing

Fork it ( https://github.com/andrba/hungryform/fork )
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create a new Pull Request

hungryform

Development

Runtime