Implement the service constraints viewlet.

app/store/env/fakebackend.js

 /*
 This file is part of the Juju GUI, which lets users view and manage Juju
 environments within a graphical interface (https://launchpad.net/juju-gui).
 Copyright (C) 2012-2013 Canonical Ltd.
 
 This program is free software: you can redistribute it and/or modify it under
 the terms of the GNU Affero General Public License version 3, as published by
 the Free Software Foundation.
 
 This program is distributed in the hope that it will be useful, but WITHOUT
@@ skipping 1056 matching lines @@
       }
 
       var existing = service.get('config');
       if (!existing) {
         existing = {};
       }
 
       if (!config) {
         config = {};
       }
-      // Merge new constraints in.
+      // Merge new config in.
       existing = Y.mix(existing, config, true, undefined, 0, true);
       //TODO: validate the config.
       // Reassign the attr.
       service.set('config', existing);
       // The callback indicates done, we can pass anything back.
       this.changes.services[service.get('id')] = [service, true];
       return {result: existing};
     },
 
     /**
@@ skipping 17 matching lines @@
       }
 
       var existing = service.get('constraints');
       if (!existing) {
         existing = {};
       }
 
       if (Y.Lang.isArray(data)) {
         Y.Array.each(data, function(i) {
           var kv = i.split('=');
-          if (kv[1]) {
-            constraints[kv[0]] = kv[1];
-          }
+          constraints[kv[0]] = kv[1];
         });
       } else if (data) {
         constraints = data;
       }
       // Merge new constraints in.
       existing = Y.mix(existing, constraints, true, undefined, 0, true);
       // TODO: Validate the constraints.
       // Reassign the attr.
       service.set('constraints', existing);
       this.changes.services[service.get('id')] = [service, true];
@@ skipping 262 matching lines @@
   Y.namespace('juju.environments').FakeBackend = FakeBackend;
 
 }, '0.1.0', {
   requires: [
     'base',
     'js-yaml',
     'juju-models',
     'promise'
   ]
 });