将其他字段动态添加到rails表单

# app/models/project.rb
class Project < ApplicationRecord
  has_many :tasks, dependent: :destroy
  accepts_nested_attributes_for :tasks, allow_destroy: true, reject_if: proc { |attributes| attributes['name'].blank? }
end

# app/models/task.rb
class Task < ApplicationRecord
  belongs_to :project
end

# app/controllers/projects_controller.rb
class ProjectsController < ApplicationController
  def new
    @project = Project.new
    @project.tasks.build
  end

  def edit
    @project = Project.find(params[:id])
  end

  private

  def project_params
    params.require(:project).permit(:name, tasks_attributes: [:id, :name, :_destroy])
  end
end

<!-- app/views/projects/_form.html.erb -->
<%= form_with(model: project, local: true) do |form| %>
  <%= form.label :name %>
  <%= form.text_field :name %>

  <%= form.fields_for :tasks do |task_form| %>
    <%= render 'task_fields', f: task_form %>
  <% end %>
  <div class='links'>
    <%= link_to_add_fields "Add Task", form, :tasks %>
  </div>

  <%= form.submit %>
<% end %>

// app/javascript/packs/application.js 或者其他 JavaScript 文件
function link_to_add_fields(link, association, content) {
  var new_id = new Date().getTime();
  var regexp = new RegExp("new_" + association, "g");
  $(link).before(content.replace(regexp, new_id));
}

$(document).on('click', '.add_fields', function(e) {
  e.preventDefault();
  var link = $(this);
  var association = $(this).data('association');
  var content = $(this).data('content');
  link_to_add_fields(link, association, content);
});

# app/helpers/application_helper.rb
module ApplicationHelper
  def link_to_add_fields(name, f, association)
    new_object = f.object.send(association).klass.new
    id = new_object.object_id
    fields = f.fields_for(association, new_object, child_index: id) do |builder|
      render(association.to_s.singularize + "_fields", f: builder)
    end
    link_to(name, '#', class: "add_fields", data: {id: id, fields: fields.gsub("\n", "")})
  end
end