diff --git a/lib/active_admin_import/importer.rb b/lib/active_admin_import/importer.rb
index ee42798..9193f26 100644
--- a/lib/active_admin_import/importer.rb
+++ b/lib/active_admin_import/importer.rb
@@ -2,7 +2,8 @@
 module ActiveAdminImport
   class Importer
 
-    attr_reader :resource, :options, :result, :headers, :csv_lines, :model
+    attr_reader :resource, :options, :result, :model
+    attr_accessor :csv_lines, :headers
 
     OPTIONS = [
         :validate,
@@ -85,7 +86,7 @@ def process_file
     end
 
     def prepare_headers
-      headers = self.headers.present? ? self.headers : yield
+      headers = self.headers.present? ? self.headers.map(&:to_s) : yield
       @headers = Hash[headers.zip(headers.map { |el| el.underscore.gsub(/\s+/, '_') })].with_indifferent_access
       @headers.merge!(options[:headers_rewrites].symbolize_keys.slice(*@headers.symbolize_keys.keys))
       @headers
diff --git a/spec/fixtures/files/posts_for_author.csv b/spec/fixtures/files/posts_for_author.csv
new file mode 100644
index 0000000..2dacf6a
--- /dev/null
+++ b/spec/fixtures/files/posts_for_author.csv
@@ -0,0 +1,3 @@
+"Title","Body"
+"title1","some body"
+"title2","some body"
\ No newline at end of file
diff --git a/spec/fixtures/files/posts_for_author_no_headers.csv b/spec/fixtures/files/posts_for_author_no_headers.csv
new file mode 100644
index 0000000..97e55bf
--- /dev/null
+++ b/spec/fixtures/files/posts_for_author_no_headers.csv
@@ -0,0 +1,2 @@
+"title1","some body"
+"title2","some body"
\ No newline at end of file
diff --git a/spec/import_spec.rb b/spec/import_spec.rb
index 6c39105..b617be3 100644
--- a/spec/import_spec.rb
+++ b/spec/import_spec.rb
@@ -4,8 +4,8 @@
 
   shared_examples 'successful inserts' do |encoding, csv_file_name|
     let(:options) do
-      attributes = { force_encoding: encoding }
-      { template_object: ActiveAdminImport::Model.new(attributes) }
+      attributes = {force_encoding: encoding}
+      {template_object: ActiveAdminImport::Model.new(attributes)}
     end
 
     before do
@@ -21,7 +21,6 @@
         expect(author.last_name).to be_present
       end
     end
-
   end
 
   def with_zipped_csv(name, &block)
@@ -36,7 +35,6 @@ def with_zipped_csv(name, &block)
     ensure
       File.delete zip_file rescue nil
     end
-
   end
 
   def upload_file!(name, ext='csv')
@@ -48,35 +46,90 @@ def upload_file!(name, ext='csv')
     before do
       Author.create!(name: "John", last_name: "Doe")
       Author.create!(name: "Jane", last_name: "Roe")
-      add_post_resource({
-        validate: true,
-        headers_rewrites: {
-          :'Author Name' => :author_id
-        },
-        before_batch_import: ->(importer) do
-          authors_names = importer.values_at(:author_id)
-          # replacing author name with author id
-          authors   = Author.where(name: authors_names).pluck(:name, :id)
-          #{"Jane" => 2, "John" => 1}
-          options = Hash[*authors.flatten]
-          importer.batch_replace(:author_id, options)
-        end
-      })
-      visit "/admin/posts/import"
-      upload_file!(:posts)
     end
 
-    it "should resolve author_id by author name" do
-      Post.all.each do |post|
-        expect(Author.where(id: post.author.id)).to be_present
+    context "for csv for particular author" do
+       let(:author){
+         Author.take
+       }
+
+       shared_examples 'successful inserts for author' do
+         it "should use predefined author_id" do
+           expect(Post.where(author_id: author.id).count).to eq(Post.count)
+         end
+
+         it "should be imported" do
+           expect(Post.count).to eq(2)
+           expect(page).to have_content "Successfully imported 2 posts"
+         end
+       end
+
+       context "no headers" do
+         before do
+           add_post_resource({
+              template_object: ActiveAdminImport::Model.new( { author_id: author.id , csv_headers: [:title, :body, :author_id] }),
+              validate: true,
+              before_batch_import: ->(importer) do
+                 importer.csv_lines.map! { |row| row << importer.model.author_id }
+              end
+           })
+
+           visit "/admin/posts/import"
+           upload_file!(:posts_for_author_no_headers)
+         end
+         include_examples 'successful inserts for author'
+       end
+
+      context "with headers" do
+        before do
+          add_post_resource({
+                              template_object: ActiveAdminImport::Model.new( { author_id: author.id }),
+                              validate: true,
+                              before_batch_import: ->(importer) do
+                                importer.csv_lines.map! { |row| row << importer.model.author_id }
+                                importer.headers.merge!({:'Author Id' => :author_id })
+                              end
+                          })
+
+          visit "/admin/posts/import"
+          upload_file!(:posts_for_author)
+        end
+        include_examples 'successful inserts for author'
       end
     end
 
-    it "should be imported" do
-      expect(Post.count).to eq(2)
-      expect(page).to have_content "Successfully imported 2 posts"
-    end
+    context "for csv with author name" do
+      before do
+        add_post_resource({
+                              validate: true,
+                              template_object: ActiveAdminImport::Model.new,
+                              headers_rewrites: {
+                                  :'Author Name' => :author_id
+                              },
+                              before_batch_import: ->(importer) do
+                                authors_names = importer.values_at(:author_id)
+                                # replacing author name with author id
+                                authors = Author.where(name: authors_names).pluck(:name, :id)
+                                #{"Jane" => 2, "John" => 1}
+                                options = Hash[*authors.flatten]
+                                importer.batch_replace(:author_id, options)
+                              end
+                          })
+        visit "/admin/posts/import"
+        upload_file!(:posts)
+      end
+
+      it "should resolve author_id by author name" do
+        Post.all.each do |post|
+          expect(Author.where(id: post.author.id)).to be_present
+        end
+      end
 
+      it "should be imported" do
+        expect(Post.count).to eq(2)
+        expect(page).to have_content "Successfully imported 2 posts"
+      end
+    end
   end
 
   context "authors index" do
@@ -91,19 +144,14 @@ def upload_file!(name, ext='csv')
       find_link('Import Authors').click
       expect(current_path).to eq("/admin/authors/import")
     end
-
-
   end
 
   context "with custom block" do
-
-
     before do
       add_author_resource({}) do
         flash[:notice] = 'some custom message'
       end
       visit '/admin/authors/import'
-
     end
 
     it "should display notice from custom block" do
@@ -111,7 +159,6 @@ def upload_file!(name, ext='csv')
       expect(page).to have_content "some custom message"
     end
 
-
   end
 
   context "authors already exist" do
@@ -123,10 +170,10 @@ def upload_file!(name, ext='csv')
     context "having authors with the same Id" do
       before do
         add_author_resource({
-          before_batch_import: ->(importer) do
-            Author.where(id: importer.values_at("id")).delete_all
-          end
-        })
+                                before_batch_import: ->(importer) do
+                                  Author.where(id: importer.values_at("id")).delete_all
+                                end
+                            })
         visit "/admin/authors/import"
         upload_file!(:authors_with_ids)
       end
@@ -136,13 +183,11 @@ def upload_file!(name, ext='csv')
         expect(Author.count).to eq(2)
       end
 
-      it "should replace authors by id"  do
+      it "should replace authors by id" do
         expect(Author.find(1).name).to eq("John")
         expect(Author.find(2).name).to eq("Jane")
       end
-
     end
-
   end
 
   context "with valid options" do
@@ -154,7 +199,6 @@ def upload_file!(name, ext='csv')
       visit '/admin/authors/import'
     end
 
-
     it "has valid form" do
       form = find('#new_active_admin_import_model')
       expect(form['action']).to eq("/admin/authors/do_import")
@@ -169,7 +213,7 @@ def upload_file!(name, ext='csv')
 
     context "with hint defined" do
       let(:options) do
-        { template_object: ActiveAdminImport::Model.new(hint: "hint") }
+        {template_object: ActiveAdminImport::Model.new(hint: "hint")}
       end
       it "renders hint at upload page" do
         expect(page).to have_content options[:template_object].hint
@@ -209,17 +253,14 @@ def upload_file!(name, ext='csv')
       end
 
       context "BOM" do
-
         it "should import file with many records" do
           upload_file!(:authors_bom)
           expect(page).to have_content "Successfully imported 2 authors"
           expect(Author.count).to eq(2)
         end
-
       end
 
       context "with headers" do
-
         it "should import file with many records" do
           upload_file!(:authors)
           expect(page).to have_content "Successfully imported 2 authors"
@@ -231,16 +272,13 @@ def upload_file!(name, ext='csv')
           expect(page).to have_content "Successfully imported 1 author"
           expect(Author.count).to eq(1)
         end
-
       end
 
-
       context "without headers" do
         context "with known csv headers" do
-
           let(:options) do
-            attributes = { csv_headers: ['Name', 'Last name', 'Birthday'] }
-            { template_object: ActiveAdminImport::Model.new(attributes) }
+            attributes = {csv_headers: ['Name', 'Last name', 'Birthday']}
+            {template_object: ActiveAdminImport::Model.new(attributes)}
           end
 
           it "should import file" do
@@ -248,7 +286,6 @@ def upload_file!(name, ext='csv')
             expect(page).to have_content "Successfully imported 2 authors"
             expect(Author.count).to eq(2)
           end
-
         end
 
         context "with unknown csv headers" do
@@ -269,7 +306,6 @@ def upload_file!(name, ext='csv')
       end
 
       context "with invalid records" do
-
         context "with validation" do
           it "should render error" do
             upload_file!(:author_invalid)
@@ -278,23 +314,18 @@ def upload_file!(name, ext='csv')
           end
         end
 
-
         context "without validation" do
-          let(:options) { { validate: false } }
+          let(:options) { {validate: false} }
           it "should render error" do
             upload_file!(:author_invalid)
             expect(page).to have_content "Successfully imported 1 author"
             expect(Author.count).to eq(1)
           end
-
         end
-
-
       end
 
       context "when zipped" do
         context "when allowed" do
-
           it "should import file" do
             with_zipped_csv(:authors) do
               upload_file!(:authors, :zip)
@@ -302,13 +333,12 @@ def upload_file!(name, ext='csv')
               expect(Author.count).to eq(2)
             end
           end
-
         end
 
         context "when not allowed" do
           let(:options) do
-            attributes = { allow_archive: false }
-            { template_object: ActiveAdminImport::Model.new(attributes) }
+            attributes = {allow_archive: false}
+            {template_object: ActiveAdminImport::Model.new(attributes)}
           end
           it "should render error" do
             with_zipped_csv(:authors) do
@@ -321,9 +351,8 @@ def upload_file!(name, ext='csv')
       end
 
       context "with different header attribute names" do
-
         let(:options) do
-          { headers_rewrites: {:'Second name' => :last_name} }
+          {headers_rewrites: {:'Second name' => :last_name}}
         end
 
         it "should import file" do
@@ -334,10 +363,9 @@ def upload_file!(name, ext='csv')
       end
 
       context "with semicolons separator" do
-
         let(:options) do
-          attributes = { csv_options: { col_sep: ";" } }
-          { template_object: ActiveAdminImport::Model.new(attributes) }
+          attributes = {csv_options: {col_sep: ";"}}
+          {template_object: ActiveAdminImport::Model.new(attributes)}
         end
 
         it "should import file" do
@@ -346,21 +374,18 @@ def upload_file!(name, ext='csv')
           expect(Author.count).to eq(2)
         end
       end
-
     end
 
-
     context "with callback procs options" do
       let(:options) do
         {
-          before_import: ->(_) { true },
-          after_import: ->(_) { true },
-          before_batch_import: ->(_) { true },
-          after_batch_import: ->(_) { true }
+            before_import: ->(_) { true },
+            after_import: ->(_) { true },
+            before_batch_import: ->(_) { true },
+            after_batch_import: ->(_) { true }
         }
       end
 
-
       it "should call each callback" do
         expect(options[:before_import]).to receive(:call).with(kind_of(ActiveAdminImport::Importer))
         expect(options[:after_import]).to receive(:call).with(kind_of(ActiveAdminImport::Importer))
@@ -374,7 +399,7 @@ def upload_file!(name, ext='csv')
   end
 
   context "with invalid options" do
-    let(:options) { { invalid_option: :invalid_value } }
+    let(:options) { {invalid_option: :invalid_value} }
 
     it "should raise TypeError" do
       expect { add_author_resource(options) }.to raise_error(ArgumentError)
@@ -382,5 +407,4 @@ def upload_file!(name, ext='csv')
 
   end
 
-
 end
\ No newline at end of file