# Nested Form Conveniently manage multiple nested models in a single form. It does so in an unobtrusive way through jQuery. This gem works with Rails 3+. ## Setup Add it to your Gemfile then run `bundle` to install it. ```ruby gem 'nested_form' ``` And then add it to the Asset Pipeline in `app/assets/javascripts/application.js` file: ``` //= require jquery_nested_form ``` ### Non Asset Pipeline Setup If you do not use the asset pipeline, run this generator to create the JavaScript file. ```bash rails g nested_form:install ``` You can then include the generated JavaScript in your layout. ```erb <%= javascript_include_tag :defaults, "nested_form" %> ``` ### Rails 5+ and Webpacker As Nested Form is a very old project, support for a NPM package was never provided and although being old enough, this gem works fine with newer versions of Rails up until 5.2.3. If you're using [webpacker](https://github.com/rails/webpacker) and want to introduce Nested Form to your project, you can use the NPM verion that is just an entrypoint to the file located in `vendor/assets/javascripts/jquery_nested_form`. > You can manually download the file and import it as well but I wanted to try publishing it to NPM. Add it to your project with: ```bash $ yarn add jquery_nested_form ``` And import it in your `application.js` pack: ```javascript import 'jquery_nested_form' ``` ## Usage - [Strong Parameters](#strong-parameters) - [SimpleForm and Formtastic Support](#simpleform-and-formtastic-support) - [Partials](#partials) - [Specifying target when adding Nested Fields](#specifying-target-when-adding-nested-fields) - [Specifying wrapper to remove Nested Fields](#specifying-wrapper-to-remove-nested-fields) Imagine you have a `Project` model that `has_many :tasks`. To be able to use this gem, you'll need to add `accepts_nested_attributes_for :tasks` to your Project model. If you wish to allow the nested objects to be destroyed, then add the `:allow_destroy => true` option to that declaration. > See the [accepts_nested_attributes_for documentation](http://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html#method-i-accepts_nested_attributes_for) for details on all available options. This will create a `tasks_attributes=` method, so you may need to add it to the `attr_accessible` array (`attr_accessible :tasks_attributes`). Then use the `nested_form_for` helper method to enable the nesting. ```erb <%= nested_form_for @project do |f| %> ``` You will then be able to use `link_to_add` and `link_to_remove` helper methods on the form builder in combination with fields_for to dynamically add/remove nested records. ```erb <%= f.fields_for :tasks do |task_form| %> <%= task_form.text_field :name %> <%= task_form.link_to_remove "Remove this task" %> <% end %>

<%= f.link_to_add "Add a task", :tasks %>

``` In order to choose how to handle, after validation errors, fields that are marked for destruction, the `marked_for_destruction` class is added on the div if the object is marked for destruction. ### Strong Parameters For Rails 4+ here is an example: ```ruby params.require(:project).permit(:name, tasks_attributes: [:id, :name, :_destroy]) ``` The `:id` is to make sure you do not end up with a whole lot of tasks. The `:_destroy` must be there so that we can delete tasks. ### SimpleForm and Formtastic Support Use `simple_nested_form_for` or `semantic_nested_form_for` for SimpleForm and Formtastic support respectively. ### Partials It is often desirable to move the nested fields into a partial to keep things organized. If you don't supply a block to fields_for it will look for a partial and use that. ```erb <%= f.fields_for :tasks %> ``` In this case it will look for a partial called "task_fields" and pass the form builder as an `f` variable to it. ### Specifying target when adding Nested Fields By default, `link_to_add` appends fields immediately before the link when clicked. This is not desirable when using a list or table, for example. In these situations, the "data-target" attribute can be used to specify where new fields should be inserted. ```erb <%= f.fields_for :tasks, :wrapper => false do |task_form| %> <% end %>

<%= task_form.text_field :name %>

<%= task_form.link_to_remove "Remove this task" %>

<%= f.link_to_add "Add a task", :tasks, :data => { :target => "#tasks" } %>

``` ### Specifying wrapper to remove Nested Fields By default, `link_to_remove` works by hiding all fields wrapped in div element with `.fields` class. Having this wrapper is completely optional and can be disabled with `wrapper: false`. However, when disabling the wrapper, `link_to_remove` stops working because it needs to somehow reference the DOM element that holds all fields to "remove". When using `wrapper: false`, normally one would introduce a default wrapper. Maybe because of a normal wrapper like a bootstrap `.row`. In those cases, the custom wrapper **class name** should be specify in the `link_to_remove` helper: ```erb <%= f.link_to_remove 'Quitar', data: { wrapper: '.row' } %> ``` > Notice the use of CSS dot notation for class name `.row` ## JavaScript events Sometimes you want to do some additional work after element was added or removed, but only after DOM was _really_ modified. In this case simply listening for click events on 'Add new'/'Remove' link won't reliably work, because your code and code that inserts/removes nested field will run concurrently. This problem can be solved, because after adding or removing the field a set of custom events is triggered on this field. Using form example from above, if you click on the "Add a task" link, `nested:fieldAdded` and `nested:fieldAdded:tasks` will be triggered, while `nested:fieldRemoved` and `nested:fieldRemoved:tasks` will be triggered if you click "Remove this task" then. These events bubble up the DOM tree, going through `form` element, until they reach the `document`. This allows you to listen for the event and trigger some action accordingly. Field element, upon which action was made, is passed along with the `event` object. In jQuery you can access it via `event.field`. For example, you have a date input in a nested field and you want to use jQuery datepicker for it. This is a bit tricky, because you have to activate datepicker after field was inserted. See example below for jQuery: ```javascript $(document).on('nested:fieldAdded', function(event){ // this field was just inserted into your form var field = event.field; // it's a jQuery object already! Now you can find date input var dateField = field.find('.date'); // and activate datepicker on it dateField.datepicker(); }) ``` Second type of event (i.e. `nested:fieldAdded:tasks`) is useful then you have more than one type of nested fields on a form (i.e. tasks and milestones) and want to distinguish, which exactly was added/deleted. > See also [how to limit max count of nested fields](https://github.com/ryanb/nested_form/wiki/How-to:-limit-max-count-of-nested-fields) ## Enhanced jQuery JavaScript template You can override default behavior of inserting new subforms into your form. For example: ```javascript window.nestedFormEvents.insertFields = function(content, assoc, link) { return $(link).closest('form').find(assoc + '_fields').append($(content)); } ``` ## Contributing If you have any issues with Nested Form not addressed above or in the [example project](https://github.com/ryanb/complex-form-examples/tree/nested_form), please add an [issue on GitHub](https://github.com/ryanb/nested_form/issues) or [fork the project](https://help.github.com/articles/fork-a-repo) and send a [pull request](https://help.github.com/articles/using-pull-requests). To run the specs: ``` bundle install bundle exec rake spec:install bundle exec rake db:migrate bundle exec rake spec:all ``` See available rake tasks using `bundle exec rake -T`. ## Special Thanks This gem was originally based on the solution by Tim Riley in his [complex-form-examples fork](https://github.com/timriley/complex-form-examples/tree/unobtrusive-jquery-deep-fix2). Thank you Andrew Manshin for the Rails 3 transition, [Andrea Singh](https://github.com/madebydna) for converting to a gem and [Peter Giacomo Lombardo](https://github.com/pglombardo) for Prototype support. Andrea also wrote a great [blog post](http://blog.madebydna.com/all/code/2010/10/07/dynamic-nested-froms-with-the-nested-form-gem.html) on the internal workings of this gem. Thanks [Pavel Forkert](https://github.com/fxposter) for the SimpleForm and Formtastic support.

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