# cocoon [![Build Status](http://travis-ci.org/nathanvda/cocoon.png)](http://travis-ci.org/nathanvda/cocoon) cocoon is a Rails3 gem to allow easier handling of nested forms. Nested forms are forms that handle nested models and attributes in one form. For example a project with its tasks, an invoice with its ordered items. It is formbuilder-agnostic, so it works with standard Rails, or Formtastic or simple_form. ## Prerequisites This gem uses jQuery, it is most useful to use this gem in a rails3 project where you are already using jQuery. Furthermore i would advice you to use either formtastic or simple_form. I have a sample project where I demonstrate the use of cocoon with formtastic. ## Installation Inside your `Gemfile` add the following: ````ruby gem "cocoon" ```` ### Rails 3.1 Add the following to `application.js` so it compiles to the asset_pipeline ````ruby //= require cocoon ```` ### Rails 3.x If you are using Rails 3.0.x, you need to run the installation task (since rails 3.1 this is no longer needed): ````ruby rails g cocoon:install ```` This will install the needed javascript file. Inside your `application.html.haml` you will need to add below the default javascripts: ````haml = javascript_include_tag :cocoon ```` or using erb, you write ````ruby <%= javascript_include_tag :cocoon %> ```` That is all you need to do to start using it! ## Usage Suppose you have a model `Project`: ````ruby rails g scaffold Project name:string description:string ```` and a project has many `tasks`: ````ruby rails g model Task description:string done:boolean project_id:integer ```` Edit the models to code the relation: ````ruby class Project < ActiveRecord::Base has_many :tasks accepts_nested_attributes_for :tasks, :reject_if => :all_blank, :allow_destroy => true end class Task < ActiveRecord::Base belongs_to :project end ```` What we want to achieve is to get a form where we can add and remove the tasks dynamically. What we need for this, is that the fields for a new/existing `task` are defined in a partial view called `_task_fields.html`. We will show the sample usage with the different possible form-builders. ### Using formtastic Inside our `projects/_form` partial we then write: ````haml - f.inputs do = f.input :name = f.input :description %h3 Tasks #tasks = f.semantic_fields_for :tasks do |task| = render 'task_fields', :f => task .links = link_to_add_association 'add task', f, :tasks -f.buttons do = f.submit 'Save' ```` and inside the `_task_fields` partial we write: ````haml .nested-fields = f.inputs do = f.input :description = f.input :done, :as => :boolean = link_to_remove_association "remove task", f ```` That is all there is to it! There is an example project on github implementing it called [cocoon_formtastic_demo](https://github.com/nathanvda/cocoon_formtastic_demo). ### Using simple_form This is almost identical to formtastic, instead of writing `semantic_fields_for` you write `simple_fields_for`. There is an example project on github implementing it called [cocoon_simple_form_demo](https://github.com/nathanvda/cocoon_simple_form_demo). ### Using standard rails forms I will provide a full example (and a sample project) later. ## How it works I define two helper functions: ### link_to_add_association This function will add a link to your markup that will, when clicked, dynamically add a new partial form for the given association. This should be placed below the `semantic_fields_for`. It takes four parameters: - name: the text to show in the link - f: referring to the containing form-object - association: the name of the association (plural) of which a new instance needs to be added (symbol or string). - html_options: extra html-options (see `link_to`) There are some special options, the first three allow to control the placement of the new link-data: - `data-association-insertion-node` : the jquery selector of the node - `data-association-insertion-method` : jquery method that inserts the new data. `before`, `after`, `append`, `prepend`, etc. Default: `before` - `data-association-insertion-position` : old method specifying where to insert new data. - this setting still works but `data-association-insertion-method` takes precedence. may be removed in a future version. - `partial`: explicitly declare the name of the partial that will be used - `render_options` : options passed through to the form-builder function (e.g. `simple_fields_for`, `semantic_fields_for` or `fields_for`). Optionally you could also leave out the name and supply a block that is captured to give the name (if you want to do something more complicated). #### :render_options Inside the `html_options` you can add an option `:render_options`, and the containing hash will be handed down to the form-builder for the inserted form. E.g. especially when using `twitter-bootstrap` and `simple_form` together, the `simple_fields_for` needs the option `:wrapper => 'inline'` which can be handed down as follows: ````haml = link_to_add_association 'add something', f, :something, :render_options => {:wrapper => 'inline' } ```` #### :partial To overrule the default partial name, e.g. because it shared between multiple views, write ````haml = link_to_add_association 'add something', f, :something, :partial => 'shared/something_fields' ```` ### link_to_remove_association This function will add a link to your markup that will, when clicked, dynamically remove the surrounding partial form. This should be placed inside the partial `__fields`. It takes three parameters: - name: the text to show in the link - f: referring to the containing form-object - html_options: extra html-options (see `link_to`) Optionally you could also leave out the name and supply a block that is captured to give the name (if you want to do something more complicated). ### Callbacks (upon insert and remove of items) There is an option to add a callback on insertion or removal. If in your view you have the following snippet to select an `owner` (we use slim for demonstration purposes) ````haml #owner #owner_from_list = f.association :owner, :collection => Person.all(:order => 'name'), :prompt => 'Choose an existing owner' = link_to_add_association 'add a new person as owner', f, :owner ```` This view part will either let you select an owner from the list of persons, or show the fields to add a new person as owner. The callbacks can be added as follows: ````javascript $(document).ready(function() { $('#owner').bind('insertion-callback', function() { $("#owner_from_list").hide(); $("#owner a.add_fields").hide(); }); $('#owner').bind("removal-callback", function() { $("#owner_from_list").show(); $("#owner a.add_fields").show(); }); $('#owner').bind("after-removal-callback", function() { /* e.g. recalculate order of child items */ }); }); ```` Do note that for the callbacks to work there has to be a surrounding container (div), where you can bind the callbacks to. Note that the default `removal-callback` is called _before_ removing the nested item. ### Control the Insertion behaviour The default insertion location is at the back of the current container. But we have added two `data`-attributes that are read to determine the insertion-node and -method. For example: ````javascript $(document).ready(function() { $("#owner a.add_fields"). data("association-insertion-method", 'before'). data("association-insertion-node", 'this'); }); ```` The `association-insertion-node` will determine where to add it. You can choose any selector here, or specify this (default it is the parent-container). The `association-insertion-method` will determine where to add it in relation with the node. Any jQuery DOM Manipulation method can be set but we recommend sticking to any of the following: `before`, `after`, `append`, `prepend`. It is unknown at this time what others would do. ### Partial If no explicit partial-name is given, `cocoon` looks for a file named `__fields`. To override the default partial-name use the option `:partial`. For the javascript to behave correctly, the partial should start with a container (e.g. `div`) of class `.nested-fields`. There is no limit to the amount of nesting, though. ## Note on Patches/Pull Requests * Fork the project. * Make your feature addition or bug fix. * Add tests for it. This is important so I don't break it in a future version unintentionally. * Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull) * Send me a pull request. Bonus points for topic branches. ## Todo * add more sample relations: `has_many :through`, `belongs_to`, ... * improve the tests (test the javascript too)(if anybody wants to lend a hand ...?) ## Copyright Copyright (c) 2010 Nathan Van der Auwera. See LICENSE for details.