Watch Prototype

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I promised myself in yesterday's retrospective that I would limit the number of couch_docs version 1.1 features to the bare minimum. Between that and a desire to have something to work on at the next B'more on Rails open source hack night, one might think that I would just call it a release and move on.

But no, I want just one more feature...

Specifically I would like the ability to watch a couch_docs document directory on the file system such that any changes cause an upload to the CouchDB server.

Rather than rolling my own directory watcher, I think I will give directory_watcher a whirl. I have not used it before, so I will prototype to learn here.

First up, install the gem:

cstrom@whitefall:~/repos/couch_docs$ gem install directory_watcher
WARNING:  Installing to ~/.gem since /var/lib/gems/1.8 and
          /var/lib/gems/1.8/bin aren't both writable.
Successfully installed directory_watcher-1.3.1
1 gem installed

Next, I add a -w option to the command line:

        opts.on("-w", "Watch for changes") do 
          @options[:watch] = true
        end

Then, when :watch is true, run with the directory_watcher gem:

        if @options[:watch]
          dw = DirectoryWatcher.new @options[:target_dir]
          dw.glob = '**/*.js'
          dw.add_observer do |*args|
            puts "Change detected pushing anew..."
            CouchDocs.put_dir(@options[:couchdb_url],
                              @options[:target_dir])
          end

          dw.start
          gets      # when the user hits "enter",
                    # the script will terminate
          dw.stop
        else
...

With that, I run with the new command line option:

cstrom@whitefall:~/repos/couch_docs$ ./bin/couch-docs push -w http://localhost:5984/seed ~/tmp/seed/
Change detected pushing anew...

Hmmm... That is a little weird. There is not a change per se, just an initial load. No matter, this is just prototype code. I can worry about cleaning it up later. To test that this works, I edit a .js file

function (doc) {
  // TESTING!!!!!!!!!!!!!
  if (doc['type'] == 'Meal' && doc['published']) {
    emit(doc['date'], doc);
  }
}

After a looooong wait (I will have to investigate frequency options later), I see:

cstrom@whitefall:~/repos/couch_docs$ ./bin/couch-docs push -w http://localhost:5984/seed ~/tmp/seed/
Change detected pushing anew...
Change detected pushing anew...

And, sure enough the change shows up automatically in the design document on the CouchDB server:


Nice! I like that feature. I will dump this prototype code and implement for real tomorrow.

Day #38