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749

answers:

3

We've all seen the brilliant complex forms railscast where Ryan Bates explains how to dynamically add or remove nested objects within the parent object form using Javascript.

Has anyone got any ideas about how these methods need to be modified so as to work with Haml Formtastic?

To add some context here's a simplified version of the problem I'm currently facing:

# Teacher form (which has nested subject forms) [from my application]

- semantic_form_for(@teacher) do |form|
  - form.inputs do
    = form.input :first_name
    = form.input :surname
    = form.input :city
    = render 'subject_fields', :form => form 
    = link_to_add_fields "Add Subject", form, :subjects   

# Individual Subject form partial [from my application]

- form.fields_for :subjects do |ff| 
  #subject_field
    = ff.input :name
    = ff.input :exam
    = ff.input :level
    = ff.hidden_field :_destroy
    = link_to_remove_fields "Remove Subject", ff 

# Application Helper (straight from Railscasts)

  def link_to_remove_fields(name, f)
    f.hidden_field(:_destroy) + link_to_function(name, "remove_fields(this)")
  end

  def link_to_add_fields(name, f, association)
    new_object = f.object.class.reflect_on_association(association).klass.new
    fields = f.fields_for(association, new_object, :child_index => "new_#{association}") do |builder|
      render(association.to_s.singularize + "_fields", :f => builder)
    end
    link_to_function(name, h("add_fields(this, \"#{association}\", \"#{escape_javascript(fields)}  \")"))
  end

#Application.js (straight from Railscasts)

  function remove_fields(link) {
  $(link).previous("input[type=hidden]").value = "1";
  $(link).up(".fields").hide();
  }

function add_fields(link, association, content) {
  var new_id = new Date().getTime();
  var regexp = new RegExp("new_" + association, "g")
  $(link).up().insert({
    before: content.replace(regexp, new_id)
  });
  }

The problem with implementation seems to be with the javascript methods - the DOM tree of a Formtastic form differs greatly from a regular rails form.

I've seen this question asked online a few times but haven't come across an answer yet - now you know that help will be appreciated by more than just me!

Jack

+3  A: 

You're on the right track:

...the DOM tree of a Formtastic form differs greatly from a regular rails form.

To adapt Ryan's example for formtastic, it's helpful to be reminded that the semantic_fields_for helper is similar to the semantic_form_for helper, which outputs the inputs in list form.

To keep things as close to the Railscast code as possible, you'll need to:

  • enclose the collection of nested fields in a wrapper (I use a div with the subjects CSS ID.)
  • enclose the nested fields in a ul/ol wrapper (I applied a nested-fields CSS class.)

Here's what your files should like.

Teacher form (with nested Subject fields):

- semantic_form_for(@teacher) do |form|
  - form.inputs do
    = form.input :first_name
    = form.input :surname
    = form.input :city

    %h2 Subjects
    #subjects
      - form.semantic_fields_for :subjects do |builder|
        = render :partial => "subject_fields", :locals => { :f => builder }
      .links
        = link_to_add_fields "Add Subject", form, :subjects

Subject fields partial (for nested Subject):

%ul.nested-fields
  = f.input :name
  = f.input :exam
  = f.input :level
  = link_to_remove_fields "Remove Subject", f

ApplicationHelper:

def link_to_remove_fields(name, f)
  f.hidden_field(:_destroy) + link_to_function(name, "remove_fields(this)")
end

def link_to_add_fields(name, f, association)
  new_object = f.object.class.reflect_on_association(association).klass.new
  fields = f.fields_for(association, new_object, :child_index => "new_#{association}") do |builder|
    render(association.to_s.singularize + "_fields", :f => builder)
  end
  link_to_function(name, h("add_fields(this, \"#{association}\", \"#{escape_javascript(fields)}\")"))
end

Application.js:

function remove_fields(link) {
  $(link).previous("input[type=hidden]").value = "1";
  $(link).up(".nested-fields").hide();
}

function add_fields(link, association, content) {
  var new_id = new Date().getTime();
  var regexp = new RegExp("new_" + association, "g")
  $(link).up().insert({
    before: content.replace(regexp, new_id)
  });
}

Using following gems:

  • formtastic (0.9.10)
  • haml (3.0.2)
  • gherkin (1.0.26)
  • rails (2.3.5)
Bennett
Thanks for your solution -- so the subject fields are displaying as are the buttons but I get scrolled to the top of the screen with no action when I click the either link (I have js defaults on in case you were wondering). I tried Steve's solution and with that the remove link works but unfortunately not the add button. It may be a case that my markup could be a little different -- using Rails 3 and latest Formtastic. Any ideas?
Jack Kinsella
I've only tried this setup with the gems that I listed above.
Bennett
Also, it doesn't sound like you're following my example exactly so you might have your form structured differently. I recommend that you get the link_to_add_fields and add_fields helper working first before moving on to removing fields.
Bennett
A: 

application.js for jQuery:

function remove_fields(link) {
  $(link).prev("input[type=hidden]").val("1");
  $(link).parent(".nested-fields").hide();
}

function add_fields(link, association, content) {
  var new_id = new Date().getTime();
  var regexp = new RegExp("new_" + association, "g")
  $(link).parent().before(content.replace(regexp, new_id));
}
Steve
Thanks -- with this the remove button worked fine but not the add button.... using Rails3 and latest Formtastic.
Jack Kinsella
A: 

In Rails 3, there's no need to use the h() function in the helper. Just omit and it should work.

Nolan