How to use Bundler with offline .gem file?

I'm using Rails 3.0.3, new to Rails 3 and bundler.

I got this same error with:

gem 'mygem', :path => '/path/to/gem'

Resolved by specifying the version number:

gem 'mygem', '0.0.1', :path => '/path/to/gem'

Using >=0.0.1 for the version reverted to the original error. I can't explain any of this, however.

Quoting JD's helpful commment, from the Gemfile man page: "Similar to the semantics of the :git option, the :path option requires that the directory in question either contains a .gemspec for the gem, or that you specify an explicit version that bundler should use."

Try unpacking the gem and then using the path in your Gemfile.

i.e.

gem unpack my-gem-file.gem /my-rails-app/vendor/gems/

then add a line like so to your Gemfile

gem 'my-gem', '0.0.1', :path => 'vendor/gems/my-gem'

Obviously paths and version numbers will vary. You also might need to make the vendor/gems directory in your app root if it doesn't already exist.

Copy the gem in to vendor/cache directory in your application's root folder.

bundle install --local

This will install the local gem.