allow creating nested form for has-many association

Gemfile.lock

@@ -225,4 +225,4 @@ DEPENDENCIES
   webpacker (~> 5.2, >= 5.2.1)
 
 BUNDLED WITH
-   2.2.3
+   2.2.14

app/views/madmin/application/_javascript.html.erb

@@ -3,7 +3,7 @@
 <%= stylesheet_link_tag "https://unpkg.com/slim-select@1.27.0/dist/slimselect.min.css", "data-turbo-track": "reload" %>
 
 <script type="module">
-  import { Application } from 'https://cdn.skypack.dev/stimulus'
+  import { Application, Controller } from 'https://cdn.skypack.dev/stimulus'
   const application = Application.start()
 
   import stimulusFlatpickr from 'https://cdn.skypack.dev/stimulus-flatpickr'
@@ -21,4 +21,37 @@
   ActiveStorage.start()
 
   import * as Turbo from "https://cdn.skypack.dev/@hotwired/turbo"
+
+  (() => {
+    application.register('nested-form', class extends Controller {
+      static targets = [ "links", "template" ]
+
+      connect() {
+        this.wrapperClass = this.data.get("wrapperClass") || "nested-fields"
+      }
+
+      add_association(event) {
+        event.preventDefault()
+
+        var content = this.templateTarget.innerHTML.replace(/NEW_RECORD/g, new Date().getTime())
+        this.linksTarget.insertAdjacentHTML('beforebegin', content)
+      }
+
+      remove_association(event) {
+        event.preventDefault()
+
+        let wrapper = event.target.closest("." + this.wrapperClass)
+
+        // New records are simply removed from the page
+        if (wrapper.dataset.newRecord == "true") {
+          wrapper.remove()
+
+        // Existing records are hidden and flagged for deletion
+        } else {
+          wrapper.querySelector("input[name*='_destroy']").value = 1
+          wrapper.style.display = 'none'
+        }
+      }
+    })
+  })()
 </script>

app/views/madmin/fields/nested_has_many/_fields.html.erb

@@ -0,0 +1,18 @@
+<%= content_tag :div, class: "nested-fields bg-gray-100 rounded-t-xl p-5", data: { new_record: f.object.new_record? } do %>
+  <% field.nested_attributes.each do |nested_attribute| %>
+    <% next if nested_attribute[:field].nil? %>
+    <% next unless nested_attribute[:field].visible?(action_name) %>
+    <% next unless nested_attribute[:field].visible?(:form) %>
+
+    <% nested_field = nested_attribute[:field] %>
+
+    <div class="mb-4 flex">
+      <%= render partial: nested_field.to_partial_path("form"), locals: { field: nested_field, record: f.object, form: f, resource: field.resource } %>
+    </div>
+  <% end %>
+
+  <small><%= link_to "Remove", "#", data: { action: "click->nested-form#remove_association" } %></small>
+
+  <%= f.hidden_field :_destroy %>
+
+<% end %>

app/views/madmin/fields/nested_has_many/_form.html.erb

@@ -0,0 +1,30 @@
+<%= form.label field.attribute_name, class: "inline-block w-32 flex-shrink-0" %>
+
+<div class="container space-y-8" data-controller="nested-form">
+  <template data-target="nested-form.template">
+
+    <%= form.fields_for field.attribute_name, field.to_model.new, child_index: 'NEW_RECORD' do |nested_form| %>
+      <%= render(
+        partial: field.to_partial_path('fields'),
+        locals: {
+          f: nested_form,
+          field: field
+        }
+      ) %>
+  <% end %>
+  </template>
+
+    <%= form.fields_for field.attribute_name do |nested_form| %>
+      <%= render(
+        partial: field.to_partial_path('fields'),
+        locals: {
+          f: nested_form,
+          field: field
+        }
+      ) %>
+  <% end %>
+
+  <%= content_tag :div, class: '', data: { target:"nested-form.links" } do %>
+    <%= link_to "+ Add new", "#",  data: { action: "click->nested-form#add_association" } %>
+  <% end %>
+</div>

app/views/madmin/fields/nested_has_many/_index.html.erb

@@ -0,0 +1 @@
+<%= pluralize field.value(record).count, field.attribute_name.to_s %>

app/views/madmin/fields/nested_has_many/_show.html.erb

@@ -0,0 +1,5 @@
+<% field.value(record).each do |object| %>
+  <div>
+    <%= link_to Madmin.resource_for(object).display_name(object), Madmin.resource_for(object).show_path(object) %>
+  </div>
+<% end %>

lib/madmin.rb

@@ -26,6 +26,7 @@ module Fields
     autoload :RichText, "madmin/fields/rich_text"
     autoload :Attachment, "madmin/fields/attachment"
     autoload :Attachments, "madmin/fields/attachments"
+    autoload :NestedHasMany, "madmin/fields/nested_has_many"
   end
 
   mattr_accessor :resources, default: []

lib/madmin/fields/nested_has_many.rb

@@ -0,0 +1,40 @@
+module Madmin
+  module Fields
+    class NestedHasMany < Field
+      DEFAULT_ATTRIBUTES = %w[_destroy id].freeze
+      def nested_attributes
+        resource.attributes.reject { |i| skipped_fields.include?(i[:name]) }
+      end
+
+      def resource
+        "#{to_model.name}Resource".constantize
+      end
+
+      def to_param
+        {"#{attribute_name}_attributes": permitted_fields}
+      end
+
+      def to_partial_path(name)
+        unless %w[index show form fields].include? name
+          raise ArgumentError, "`partial` must be 'index', 'show', 'form' or 'fields'"
+        end
+
+        "/madmin/fields/#{self.class.field_type}/#{name}"
+      end
+
+      def to_model
+        attribute_name.to_s.singularize.classify.constantize
+      end
+
+      private
+
+      def permitted_fields
+        (resource.permitted_params - skipped_fields + DEFAULT_ATTRIBUTES).uniq
+      end
+
+      def skipped_fields
+        options[:skip] || []
+      end
+    end
+  end
+end

lib/madmin/resource.rb

@@ -140,7 +140,8 @@ def field_for_type(name, type)
           polymorphic: Fields::Polymorphic,
           has_many: Fields::HasMany,
           has_one: Fields::HasOne,
-          rich_text: Fields::RichText
+          rich_text: Fields::RichText,
+          nested_has_many: Fields::NestedHasMany
         }.fetch(type)
       rescue
         raise ArgumentError, <<~MESSAGE

test/dummy/app/madmin/resources/post_resource.rb

@@ -2,18 +2,10 @@ class PostResource < Madmin::Resource
   # Attributes
   attribute :id, form: false
   attribute :title
-  attribute :comments_count, form: false
-  attribute :metadata
-  attribute :created_at, form: false
-  attribute :updated_at, form: false
   attribute :body, index: false
   attribute :image, index: false
   attribute :attachments, index: false
   attribute :enum
 
-  # Associations
-  attribute :user
-  attribute :comments
-
   scope :recent
 end

test/dummy/app/madmin/resources/user_resource.rb

@@ -10,7 +10,7 @@ class UserResource < Madmin::Resource
   attribute :avatar, index: false
 
   # Associations
-  attribute :posts
+  attribute :posts, :nested_has_many, skip: %I[enum attachments]
   attribute :comments
   attribute :habtms
 

test/dummy/app/models/user.rb

@@ -1,5 +1,7 @@
 class User < ApplicationRecord
   has_many :posts
+  accepts_nested_attributes_for :posts, allow_destroy: true
+
   has_many :comments
   has_and_belongs_to_many :habtms, join_table: :user_habtms
 

test/madmin/nested_form_test.rb

@@ -0,0 +1,26 @@
+require "test_helper"
+
+class NestedHasManyTest < ActiveSupport::TestCase
+  test "checks for the right field class" do
+    field = UserResource.attributes.find { |i| i[:name] == :posts }[:field]
+    field_comment = UserResource.attributes.find { |i| i[:name] == :comments }[:field]
+    # Make sure :posts is a :nested_has_many type
+    assert field.instance_of?(Madmin::Fields::NestedHasMany)
+    refute field_comment.instance_of?(Madmin::Fields::NestedHasMany)
+    assert_equal field.resource, PostResource
+  end
+
+  test "skips fields which is skipped in configuration" do
+    field = UserResource.attributes.find { |i| i[:name] == :posts }[:field]
+
+    # Make sure :enum is skipped in the UserResource
+    refute field.to_param.values.flatten.include?(:enum)
+    assert field.to_param.values.flatten.include?(:body)
+  end
+
+  test "whitelists unskipped and required params" do
+    field = UserResource.attributes.find { |i| i[:name] == :posts }[:field]
+
+    assert field.to_param == {posts_attributes: [:id, :title, :body, :image, {attachments: []}, "_destroy", "id"]}
+  end
+end