Add option INCLUDE=id

README.md

@@ -96,6 +96,11 @@ Exclude `name` and `age` from the dump:
 irb(main):004:0> SeedDump.dump(User, exclude: [:name, :age])
 ```
 
+Include `id` to the dump:
+```ruby
+irb(main):005:0> SeedDump.dump(User, include: [:created_at, :updated_at])
+```
+
 Options are specified as a Hash for the second argument.
 
 In the console, any relation of ActiveRecord rows can be dumped (not individual objects though)
@@ -118,6 +123,8 @@ Options are common to both the Rake task and the console, except where noted.
 
 `exclude`: Attributes to be excluded from the dump. Pass a comma-separated list to the Rake task (i.e. `name,age`) and an array on the console (i.e. `[:name, :age]`). Default: `[:id, :created_at, :updated_at]`.
 
+`include`: Attributes to be excluded from the default excluded colmuns such as `[:id, :created_at, :updated_at]`. Pass a comma-separated list to the Rake task (i.e. `created_at,updated_at`) and an array on the console (i.e. `[:created_at, :updated_at]`). Default: `[]`.
+
 `file`: Write to the specified output file. The Rake task default is `db/seeds.rb`. The console returns the dump as a string by default.
 
 `import`: If `true`, output will be in the format needed by the [activerecord-import](https://github.com/zdennis/activerecord-import) gem, rather than the default format. Default: `false`.

lib/seed_dump/dump_methods.rb

@@ -65,9 +65,18 @@ def open_io(options)
       end
     end
 
-    def write_records_to_io(records, io, options)
+    def set_inclusions(options)
+      return unless options[:include]
+      options[:exclude] = (options[:exclude] - options[:include])
+    end
+
+    def set_exclusions(options)
       options[:exclude] ||= [:id, :created_at, :updated_at]
+    end
 
+    def write_records_to_io(records, io, options)
+      set_exclusions(options)
+      set_inclusions(options)
       method = options[:import] ? 'import' : 'create!'
       io.write("#{model_for(records)}.#{method}(")
       if options[:import]

lib/seed_dump/environment.rb

@@ -31,6 +31,7 @@ def dump_using_environment(env = {})
         model = model.limit(env['LIMIT'].to_i) if env['LIMIT']
 
         SeedDump.dump(model,
+                      include: (env['INCLUDE'] ? env['INCLUDE'].split(',').map {|i| i.strip.to_sym} : []),
                       append: append,
                       batch_size: (env['BATCH_SIZE'] ? env['BATCH_SIZE'].to_i : nil),
                       exclude: (env['EXCLUDE'] ? env['EXCLUDE'].split(',').map {|e| e.strip.to_sym} : nil),

spec/dump_methods_spec.rb

@@ -13,6 +13,87 @@ def expected_output(include_id = false, id_offset = 0)
       output + data.join(",\n  ") + "\n])\n"
   end
 
+  describe '::set_inclusions' do
+    context '"include" is not given' do
+      let(:options) do
+        { exclude: [:id, :created_at, :updated_at] }
+      end
+
+      it 'does not change "options"' do
+        SeedDump.send(:set_inclusions, options)
+        options.should eq exclude: [:id, :created_at, :updated_at]
+      end
+    end
+
+    context '"include" values is empty' do
+      let(:options) do
+        { exclude: [:id, :created_at, :updated_at], include: [] }
+      end
+
+      it 'does not change "options' do
+        SeedDump.send(:set_inclusions, options)
+        options.should eq(exclude: [:id, :created_at, :updated_at], include: [])
+      end
+    end
+
+    context '"include" values are on the "exclude" values list' do
+      let(:options) do
+        { exclude: [:id, :created_at, :updated_at],
+          include: [:id, :created_at] }
+      end
+
+      it 'returns value not on the "include" values list' do
+        SeedDump.send(:set_inclusions, options)
+        options.should eq(
+          exclude: [:updated_at],
+          include: [:id, :created_at])
+      end
+    end
+
+    context '"include" values are not on the "exclude" values list' do
+      let(:options) do
+        { exclude: [:id, :created_at, :updated_at],
+          include: [:hoge, :fuga] }
+      end
+
+      it 'does not change "option"' do
+        SeedDump.send(:set_inclusions, options)
+        options.should eq(
+          exclude: [:id, :created_at, :updated_at],
+          include: [:hoge, :fuga])
+      end
+    end
+  end
+
+  describe '::set_exclusions' do
+    context 'exclude key has no value' do
+      let(:options) { { exclude: nil } }
+
+      it '"exclude" values is default' do
+        SeedDump.send(:set_exclusions, options)
+        options.should eq(exclude: [:id, :created_at, :updated_at])
+      end
+    end
+
+    context '"exclude" key has only one value' do
+      let(:options) { { exclude: [:foo] } }
+
+      it 'returns given options' do
+        SeedDump.send(:set_exclusions, options)
+        options.should eq(exclude: [:foo])
+      end
+    end
+
+    context '"exclude" key has more than one value' do
+      let(:options) { { exclude: [:foo, :bar] } }
+
+      it 'returns given options' do
+        SeedDump.send(:set_exclusions, options)
+        options.should eq(exclude: [:foo, :bar])
+      end
+    end
+  end
+
   describe '.dump' do
     before do
       Rails.application.eager_load!