Mongoid compatibility.

app/views/admin/import.html.erb

@@ -1,11 +1,13 @@
 <p class="active_admin_import_hint">
-   <%= raw(@active_admin_import_model.hint) %> 
+   <%= raw(@active_admin_import_model.hint) %>
 </p>
 <%= semantic_form_for @active_admin_import_model, url: {action: :do_import}, html: {multipart: true} do |f| %>
     <%= f.inputs name: t("active_admin_import.details") do %>
         <%= f.input :file, as: :file %>
+        <%= f.input :col_sep, collection: [';', ','], include_blank: false, selected: ';' %>
     <% end %>
+
     <%= f.actions do %>
         <%= f.action :submit, label: t("active_admin_import.import_btn"), button_html: {data: {disable_with: t("active_admin_import.import_btn_disabled")}} %>
     <% end %>
-<% end %>
+<% end %>

lib/active_admin_import/dsl.rb

@@ -92,11 +92,7 @@ def active_admin_import(options = {}, &block)
           else
             instance_exec result, options, &DEFAULT_RESULT_PROC
           end
-        rescue ActiveRecord::Import::MissingColumnError,
-               NoMethodError,
-               ActiveRecord::StatementInvalid,
-               CSV::MalformedCSVError,
-               ActiveAdminImport::Exception => e
+        rescue StandardError => e
           Rails.logger.error(I18n.t('active_admin_import.file_error', message: e.message))
           Rails.logger.error(e.backtrace.join("\n"))
           flash[:error] = I18n.t('active_admin_import.file_error', message: e.message[0..200])

lib/active_admin_import/importer.rb

@@ -37,7 +37,7 @@ def file
     end
 
     def cycle(lines)
-      @csv_lines = CSV.parse(lines.join, @csv_options)
+      @csv_lines = lines
       import_result.add(batch_import, lines.count)
     end
 
@@ -113,17 +113,20 @@ def header_index(header_key)
     def process_file
       lines = []
       batch_size = options[:batch_size].to_i
-      File.open(file.path) do |f|
-        # capture headers if not exist
-        prepare_headers { CSV.parse(f.readline, @csv_options).first }
-        f.each_line do |line|
-          lines << line if line.present?
-          if lines.size == batch_size || f.eof?
-            cycle(lines)
-            lines = []
-          end
+
+      csv = CSV.read(file.path, @csv_options)
+
+      prepare_headers { csv.shift }
+
+      csv.each do |line|
+        lines << line
+
+        if lines.size == batch_size
+          cycle(lines)
+          lines = []
         end
       end
+
       cycle(lines) unless lines.blank?
     end
 
@@ -139,12 +142,21 @@ def run_callback(name)
     end
 
     def batch_import
+      @resource.respond_to?(:transaction) ? batch_improt_with_transaction : batch_import_without_transaction
+    end
+
+    def batch_import_without_transaction
+      run_callback(:before_batch_import)
+      batch_result = resource.import(headers.values, csv_lines, import_options)
+      raise ActiveRecord::Rollback if Object.const_defined?('ActiveRecord::Rollback') && import_options[:batch_transaction] && batch_result.failed_instances.any?
+      run_callback(:after_batch_import)
+      batch_result
+    end
+
+    def batch_improt_with_transaction
       batch_result = nil
       @resource.transaction do
-        run_callback(:before_batch_import)
-        batch_result = resource.import(headers.values, csv_lines, import_options)
-        raise ActiveRecord::Rollback if import_options[:batch_transaction] && batch_result.failed_instances.any?
-        run_callback(:after_batch_import)
+        batch_result = batch_import_without_transaction
       end
       batch_result
     end
@@ -163,6 +175,7 @@ def detect_csv_options
                      else
                        options[:csv_options] || {}
                      end.reject { |_, value| value.nil? || value == "" }
+      @csv_options[:col_sep] = model.col_sep if model.respond_to?(:col_sep)
     end
   end
 end

lib/active_admin_import/model.rb

@@ -65,7 +65,8 @@ def default_attributes
         csv_headers: [],
         file: nil,
         force_encoding: 'UTF-8',
-        hint: ''
+        hint: '',
+        col_sep: ';'
       }
     end