No need to restart Web-server now to see changes in dynamic UI.

Workflow is simpler now: edit form definition YAML-file, save it,
reload the form it affects. Voila!

Implements: feature MRN-1147
Cherry-picked from dc78dc3b68

Change-Id: I72d68c17b829f9252560ecd01335656ffba0b262

muranodashboard/panel/forms.py

@@ -20,7 +20,6 @@ from horizon import messages, exceptions
 from openstack_dashboard.api import glance
 import json
 
-from muranodashboard.panel.services import iterate_over_service_forms
 from muranodashboard.panel.services import get_service_choices
 
 log = logging.getLogger(__name__)
@@ -31,10 +30,6 @@ class WizardFormServiceType(forms.Form):
                                 choices=get_service_choices())
 
 
-FORMS = [('service_choice', WizardFormServiceType)]
-FORMS.extend(iterate_over_service_forms())
-
-
 class MarkImageForm(SelfHandlingForm):
     _metadata = {
         'windows.2012': ' Windows Server 2012',

muranodashboard/panel/services/__init__.py

@@ -21,6 +21,7 @@ from ordereddict import OrderedDict
 import yaml
 from yaml.scanner import ScannerError
 from django.utils.translation import ugettext_lazy as _
+import copy
 
 log = logging.getLogger(__name__)
 _all_services = OrderedDict()
@@ -65,12 +66,20 @@ def import_all_services():
     directory = getattr(settings, 'MURANO_SERVICES_DESC_PATH', None)
     if directory is None:
         directory = os.path.join(os.path.dirname(__file__), '../../services/')
-    log.debug("Importing service definitions from '{0}'".format(directory))
+    file_list = [f for f in os.listdir(directory) if f.endswith('.yaml')]
 
-    for filename in os.listdir(directory):
-        if not filename.endswith('.yaml'):
-            continue
+    log.debug("Removing non-existing service definitions from cache")
+    # TODO: this has O(n^2) complexity, should fix it if there are many defs
+    for filename in _all_services.keys():
+        try:
+            file_list.index(filename)
+        except ValueError:
+            del _all_services[filename]
+            log.info("Removed service '{0}' from cache".format(filename))
 
+    log.debug("Updating service definitions cache from '{0}'".format(
+        directory))
+    for filename in file_list:
         service_file = os.path.join(directory, filename)
         modified_on = os.path.getmtime(service_file)
 
@@ -100,10 +109,14 @@ def iterate_over_services():
         yield service.type, service, service.forms
 
 
-def iterate_over_service_forms():
-    for srv_type, service, forms in iterate_over_services():
-        for step, form in enumerate(forms):
-            yield '{0}-{1}'.format(srv_type, step), form
+def make_forms_getter(initial_forms=[]):
+    def _get_forms():
+        _forms = copy.copy(initial_forms)
+        for srv_type, service, forms in iterate_over_services():
+            for step, form in enumerate(forms):
+                _forms.append(('{0}-{1}'.format(srv_type, step), form))
+        return _forms
+    return _get_forms
 
 
 def service_type_from_id(service_id):
@@ -150,6 +163,9 @@ def get_service_choices():
             iterate_over_services()]
 
 
+get_forms = make_forms_getter()
+
+
 def get_service_checkers():
     import_all_services()
 
@@ -159,7 +175,7 @@ def get_service_checkers():
         return compare
 
     return [(srv_id, make_comparator(srv_id)) for srv_id, form
-            in iterate_over_service_forms()]
+            in get_forms()]
 
 
 def get_service_descriptions():

muranodashboard/panel/urls.py

@@ -21,8 +21,9 @@ from views import DetailServiceView
 from views import DeploymentsView
 from views import MarkedImagesView, MarkImageView
 from views import Wizard, EditEnvironmentView
-from forms import FORMS
-from muranodashboard.panel.services import get_service_checkers
+from forms import WizardFormServiceType
+from services import get_service_checkers
+from services import make_forms_getter
 from openstack_dashboard.dashboards.project.instances.views import DetailView
 
 VIEW_MOD = 'openstack_dashboard.dashboards.project.murano.views'
@@ -33,8 +34,9 @@ urlpatterns = patterns(
     url(r'^environments$', IndexView.as_view(), name='index'),
 
     url(r'^create/$',
-        Wizard.as_view(FORMS,
-                       condition_dict=dict(get_service_checkers())),
+        Wizard.as_view(make_forms_getter(
+            initial_forms=[('service_choice', WizardFormServiceType)]),
+            condition_dict=get_service_checkers),
         name='create'),
 
     url(r'^create_environment$', CreateEnvironmentView.as_view(),

muranodashboard/panel/views.py

@@ -15,14 +15,13 @@
 import logging
 import re
 import json
+import copy
 
 from django.core.urlresolvers import reverse, reverse_lazy
 from django.utils.translation import ugettext_lazy as _
-from django.utils.encoding import smart_text
 from django.contrib.formtools.wizard.views import SessionWizardView
 from django.http import HttpResponseRedirect
 
-
 from openstack_dashboard.api import glance
 
 from horizon import exceptions
@@ -41,16 +40,62 @@ from workflows import CreateEnvironment, UpdateEnvironment
 from tabs import ServicesTabs, DeploymentTabs
 from forms import MarkImageForm
 
-from muranodashboard.panel import api
+import api
 from muranoclient.common.exceptions import HTTPUnauthorized, \
     CommunicationError, HTTPInternalServerError, HTTPForbidden, HTTPNotFound
+from functools import update_wrapper
+from django.utils.decorators import classonlymethod
+from services import get_service_descriptions
+from services import get_service_name
+from services import get_service_field_descriptions
 
-from muranodashboard.panel.services import get_service_descriptions, \
-    get_service_name, get_service_field_descriptions
 LOG = logging.getLogger(__name__)
 
 
-class Wizard(ModalFormMixin, SessionWizardView):
+class LazyWizard(SessionWizardView):
+    """The class which defers evaluation of form_list and condition_dict
+    until view method is called. So, each time we load a page with a dynamic
+    UI form, it will have markup/logic from the newest YAML-file definition.
+    """
+    @classonlymethod
+    def as_view(cls, initforms, *initargs, **initkwargs):
+        """
+        Main entry point for a request-response process.
+        """
+        # sanitize keyword arguments
+        for key in initkwargs:
+            if key in cls.http_method_names:
+                raise TypeError(u"You tried to pass in the %s method name as a"
+                                u" keyword argument to %s(). Don't do that."
+                                % (key, cls.__name__))
+            if not hasattr(cls, key):
+                raise TypeError(u"%s() received an invalid keyword %r" % (
+                    cls.__name__, key))
+
+        def view(request, *args, **kwargs):
+            forms = initforms
+            if hasattr(initforms, '__call__'):
+                forms = initforms()
+            condition_dict = initkwargs.get('condition_dict', False)
+            _kwargs = copy.copy(initkwargs)
+            if condition_dict and hasattr(condition_dict, '__call__'):
+                _kwargs.update({'condition_dict': dict(condition_dict())})
+            _kwargs = cls.get_initkwargs(forms, *initargs, **_kwargs)
+            self = cls(**_kwargs)
+            if hasattr(self, 'get') and not hasattr(self, 'head'):
+                self.head = self.get
+            return self.dispatch(request, *args, **kwargs)
+
+        # take name and docstring from class
+        update_wrapper(view, cls, updated=())
+
+        # and possible attributes set by decorators
+        # like csrf_exempt from dispatch
+        update_wrapper(view, cls.dispatch, assigned=())
+        return view
+
+
+class Wizard(ModalFormMixin, LazyWizard):
     template_name = 'services/wizard_create.html'
 
     def done(self, form_list, **kwargs):