Add active_admin_import_context convention for controller-provided context

lib/active_admin_import/dsl.rb

@@ -25,6 +25,22 @@ module ActiveAdminImport
   # +plural_resource_label+:: pluralized resource label value (default config.plural_resource_label)
   #
   module DSL
+    CONTEXT_METHOD = :active_admin_import_context
+
+    def self.prepare_import_model(template_object, controller, params: nil)
+      model = template_object.is_a?(Proc) ? template_object.call : template_object
+      if params
+        params_key = ActiveModel::Naming.param_key(model.class)
+        model.assign_attributes(params[params_key].try(:deep_symbolize_keys) || {})
+      end
+      return model unless controller.respond_to?(CONTEXT_METHOD, true)
+      context = controller.send(CONTEXT_METHOD)
+      return model unless context.is_a?(Hash)
+      context = context.merge(file: model.file) if model.respond_to?(:file) && !context.key?(:file)
+      model.assign_attributes(context)
+      model
+    end
+
     DEFAULT_RESULT_PROC = lambda do |result, options|
       model_name = options[:resource_label].downcase
       plural_model_name = options[:plural_resource_label].downcase
@@ -57,11 +73,7 @@ def active_admin_import(options = {}, &block)
 
       collection_action :import, method: :get do
         authorize!(ActiveAdminImport::Auth::IMPORT, active_admin_config.resource_class)
-        @active_admin_import_model = if options[:template_object].is_a?(Proc)
-                                       options[:template_object].call
-                                     else
-                                       options[:template_object]
-                                     end
+        @active_admin_import_model = ActiveAdminImport::DSL.prepare_import_model(options[:template_object], self)
         render template: options[:template]
       end
 
@@ -78,13 +90,9 @@ def active_admin_import(options = {}, &block)
         authorize!(ActiveAdminImport::Auth::IMPORT, active_admin_config.resource_class)
         _params = params.respond_to?(:to_unsafe_h) ? params.to_unsafe_h : params
         params = ActiveSupport::HashWithIndifferentAccess.new _params
-        @active_admin_import_model = if options[:template_object].is_a?(Proc)
-                                       options[:template_object].call
-                                     else
-                                       options[:template_object]
-                                     end
-        params_key = ActiveModel::Naming.param_key(@active_admin_import_model.class)
-        @active_admin_import_model.assign_attributes(params[params_key].try(:deep_symbolize_keys) || {})
+        @active_admin_import_model = ActiveAdminImport::DSL.prepare_import_model(
+          options[:template_object], self, params: params
+        )
         # go back to form
         return render template: options[:template] unless @active_admin_import_model.valid?
         @importer = Importer.new(

spec/fixtures/files/post_comments.csv

@@ -0,0 +1,3 @@
+"Body"
+"First comment"
+"Second comment"

spec/import_spec.rb

@@ -626,4 +626,67 @@ def upload_file!(name, ext = 'csv')
       end.not_to change { Author.count }
     end
   end
+
+  context 'with active_admin_import_context defined on the controller' do
+    before { Author.create!(name: 'John', last_name: 'Doe') }
+
+    let(:author) { Author.take }
+
+    context 'when context returns request-derived attributes' do
+      before do
+        author_id = author.id
+        add_post_resource(
+          template_object: ActiveAdminImport::Model.new(author_id: author_id),
+          before_batch_import: lambda do |importer|
+            ip = importer.model.request_ip
+            a_id = importer.model.author_id
+            importer.csv_lines.map! { |row| row << ip << a_id }
+            importer.headers.merge!(:'Request Ip' => :request_ip, :'Author Id' => :author_id)
+          end,
+          controller_block: proc do
+            def active_admin_import_context
+              { request_ip: request.remote_ip }
+            end
+          end
+        )
+        visit '/admin/posts/import'
+        upload_file!(:posts_for_author)
+      end
+
+      it 'merges the context into the import model so callbacks see it' do
+        expect(page).to have_content 'Successfully imported 2 posts'
+        expect(Post.count).to eq(2)
+        Post.all.each do |post|
+          expect(post.request_ip).to eq('127.0.0.1')
+          expect(post.author_id).to eq(author.id)
+        end
+      end
+    end
+
+    context 'when context returns parent id for a nested belongs_to resource' do
+      let(:post) { Post.create!(title: 'A post', body: 'body', author: author) }
+
+      before do
+        add_nested_post_comment_resource(
+          before_batch_import: lambda do |importer|
+            importer.csv_lines.map! { |row| row << importer.model.post_id }
+            importer.headers.merge!(:'Post Id' => :post_id)
+          end,
+          controller_block: proc do
+            def active_admin_import_context
+              { post_id: parent.id }
+            end
+          end
+        )
+        visit "/admin/posts/#{post.id}/post_comments/import"
+        upload_file!(:post_comments)
+      end
+
+      it 'automatically assigns the parent post_id to every imported comment' do
+        expect(page).to have_content 'Successfully imported 2 post comments'
+        expect(PostComment.count).to eq(2)
+        expect(PostComment.where(post_id: post.id).count).to eq(2)
+      end
+    end
+  end
 end

spec/support/admin.rb

@@ -8,8 +8,24 @@ def add_author_resource(options = {}, &block)
 end
 
 def add_post_resource(options = {}, &block)
+  cb = options.delete(:controller_block)
   ActiveAdmin.register Post do
     config.filters = false
+    controller(&cb) if cb
+    active_admin_import(options, &block)
+  end
+  Rails.application.reload_routes!
+end
+
+def add_nested_post_comment_resource(options = {}, &block)
+  cb = options.delete(:controller_block)
+  ActiveAdmin.register Post do
+    config.filters = false
+  end
+  ActiveAdmin.register PostComment do
+    config.filters = false
+    belongs_to :post
+    controller(&cb) if cb
     active_admin_import(options, &block)
   end
   Rails.application.reload_routes!

spec/support/rails_template.rb

@@ -1,10 +1,11 @@
 create_file "app/assets/config/manifest.js", skip: true
 
 generate :model, 'author name:string{10}:uniq last_name:string birthday:date --force'
-generate :model, 'post title:string:uniq body:text author:references --force'
+generate :model, 'post title:string:uniq body:text request_ip:string author:references --force'
+generate :model, 'post_comment body:text post:references --force'
 
 inject_into_file 'app/models/author.rb', "  validates_presence_of :name\n  validates_uniqueness_of :last_name\n", before: 'end'
-inject_into_file 'app/models/post.rb', "  validates_presence_of :author\n", before: 'end'
+inject_into_file 'app/models/post.rb', "  validates_presence_of :author\n  has_many :post_comments\n", before: 'end'
 
 # Add our local Active Admin to the load path (Rails 7.1+)
 gsub_file "config/environment.rb",