fix(relation): add support of has_and_belongs_to_many relations

.rubocop.yml

@@ -1,4 +1,4 @@
-require:
+plugins:
   - rubocop-performance
   - rubocop-rspec
 
@@ -329,3 +329,6 @@ Lint/InterpolationCheck:
 Lint/UnusedMethodArgument:
   Exclude:
     - 'packages/forest_admin_rails/config/initializers/forest_admin_error_subscriber.rb'
+
+Style/RedundantParentheses:
+  Enabled: false

packages/forest_admin_agent/lib/forest_admin_agent/utils/schema/schema_emitter.rb

@@ -88,7 +88,7 @@ def serialize(schema)
 
             {
               data: data,
-              included: included.reject!(&:empty?)&.flatten,
+              included: included.reject!(&:empty?)&.flatten || [],
               meta: schema[:meta]
             }
           end

packages/forest_admin_agent/spec/lib/forest_admin_agent/utils/schema/schema_emitter_spec.rb

@@ -91,7 +91,7 @@ module Schema
             expect(schema).to eq(
               {
                 data: [],
-                included: nil,
+                included: [],
                 meta: {
                   liana: described_class::LIANA_NAME,
                   liana_version: described_class::LIANA_VERSION,
@@ -123,7 +123,7 @@ module Schema
             expect(schema).to eq(
               {
                 data: [],
-                included: nil,
+                included: [],
                 meta: json_schema[:meta]
               }
             )

packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/collection.rb

@@ -175,6 +175,18 @@ def fetch_associations
               )
             end
           end
+        when :has_and_belongs_to_many
+          add_field(
+            association.name.to_s,
+            ForestAdminDatasourceToolkit::Schema::Relations::ManyToManySchema.new(
+              foreign_collection: format_model_name(association.klass.name),
+              origin_key: association.join_primary_key,
+              origin_key_target: association.join_foreign_key,
+              foreign_key: association.association_foreign_key,
+              foreign_key_target: association.association_primary_key,
+              through_collection: association.join_table.classify
+            )
+          )
         end
       end
     end

packages/forest_admin_datasource_active_record/lib/forest_admin_datasource_active_record/datasource.rb

@@ -78,7 +78,8 @@ def fetch_model(model)
         @models << model unless model.abstract_class? ||
                                 @models.include?(model) ||
                                 !model.table_exists? ||
-                                !primary_key?(model)
+                                !primary_key?(model) ||
+                                model.const_defined?(:VIRTUAL_THROUGH_COLLECTION)
       end
     end
 
@@ -101,19 +102,24 @@ def build_habtm(model)
       if @habtm_models.key?(model.table_name)
         @habtm_models[model.table_name].left_reflection = model.right_reflection
         # when the second model is added, we can push the HABTM model to the models list
-        @models << make_through_model(
+        through_model = make_through_model(
           model.table_name,
           [
             @habtm_models[model.table_name].left_reflection,
             @habtm_models[model.table_name].right_reflection
           ]
         )
+
+        add_collection(
+          Collection.new(self, through_model, support_polymorphic_relations: @support_polymorphic_relations)
+        )
       else
         @habtm_models[model.table_name] = model
       end
     end
 
     def make_through_model(table_name, associations)
+      through_model_name = table_name.classify
       through_model = Class.new(ActiveRecord::Base) do
         class << self
           attr_accessor :name, :table_name
@@ -124,13 +130,15 @@ def self.add_association(name, options)
         end
       end
 
-      through_model.name = table_name.singularize
+      through_model.name = through_model_name
       through_model.table_name = table_name
       through_model.primary_key = [associations[0].foreign_key, associations[1].foreign_key]
       associations.each do |association|
         through_model.add_association(association.name, association.options)
       end
 
+      through_model.const_set(:VIRTUAL_THROUGH_COLLECTION, true)
+
       through_model
     end
   end

packages/forest_admin_datasource_active_record/spec/dummy/app/models/company.rb

@@ -0,0 +1,3 @@
+class Company < ApplicationRecord
+  has_and_belongs_to_many :users
+end

packages/forest_admin_datasource_active_record/spec/dummy/app/models/user.rb

@@ -1,6 +1,7 @@
 class User < ApplicationRecord
   belongs_to :car
   has_one :address, as: :addressable
+  has_and_belongs_to_many :companies
 
   enum :enum_field, { draft: 0, published: 1, archived: 2, trashed: 3 }
 end

packages/forest_admin_datasource_active_record/spec/dummy/db/migrate/20230810095726_create_companies.rb

@@ -0,0 +1,8 @@
+class CreateCompanies < ActiveRecord::Migration[7.0]
+  def change
+    create_table :companies do |t|
+      t.column :name, :string
+      t.timestamps
+    end
+  end
+end

packages/forest_admin_datasource_active_record/spec/dummy/db/migrate/20230810095727_create_companies_users.rb

@@ -0,0 +1,8 @@
+class CreateCompaniesUsers < ActiveRecord::Migration[7.0]
+  def change
+    create_table :companies_users, id: false do |t|
+      t.belongs_to :company
+      t.belongs_to :user
+    end
+  end
+end

packages/forest_admin_datasource_active_record/spec/lib/forest_admin_datasource_active_record/collection_spec.rb

@@ -35,6 +35,12 @@ module ForestAdminDatasourceActiveRecord
           expect(datasource.get_collection('User').schema[:fields].keys).not_to include('address')
           expect(datasource.get_collection('Address').schema[:fields].keys).not_to include('addressable')
         end
+
+        it 'add has_and_belongs_to_many relation' do
+          collection = described_class.new(datasource, Company)
+
+          expect(collection.schema[:fields].keys).to include('users')
+        end
       end
     end
 

packages/forest_admin_datasource_active_record/spec/lib/forest_admin_datasource_active_record/datasource_spec.rb

@@ -4,7 +4,7 @@ module ForestAdminDatasourceActiveRecord
   describe Datasource do
     it 'fetch all models' do
       datasource = described_class.new({ adapter: 'sqlite3', database: 'db/database.db' })
-      expected = %w[User Order Check Category CarCheck Car Address]
+      expected = %w[User Order Check Category CarCheck Car Address Company CompaniesUser]
 
       expect(datasource.collections.keys).to match_array(expected)
     end