135 lines
5.5 KiB
ReStructuredText
135 lines
5.5 KiB
ReStructuredText
======================
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Workflows Topic Guide
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======================
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One of the most challenging aspects of building a compelling user experience
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is crafting complex multi-part workflows. Horizon's ``workflows`` module
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aims to bring that capability within everyday reach.
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.. seealso::
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For a detailed API information check out the :doc:`Workflows Reference
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Guide </ref/workflows>`.
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Workflows
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=========
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Workflows are complex forms with tabs, each workflow must consist of classes
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extending the :class:`~horizon.workflows.Workflow`,
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:class:`~horizon.workflows.Step` and :class:`~horizon.workflows.Action`
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Complex example of workflow
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----------------------------
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The following is a complex example of how data are exchanged between
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urls, views, workflows and templates:
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#. In ``urls.py``, we have the named parameter. E.g. ``resource_class_id``. ::
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RESOURCE_CLASS = r'^(?P<resource_class_id>[^/]+)/%s$'
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urlpatterns = patterns(
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'',
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url(RESOURCE_CLASS % 'update', UpdateView.as_view(), name='update'))
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#. In ``views.py``, we pass data to the template and to the action(form)
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(action can also pass data to the ``get_context_data`` method and to the
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template). ::
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class UpdateView(workflows.WorkflowView):
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workflow_class = UpdateResourceClass
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def get_context_data(self, **kwargs):
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context = super(UpdateView, self).get_context_data(**kwargs)
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# Data from URL are always in self.kwargs, here we pass the data
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# to the template.
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context["resource_class_id"] = self.kwargs['resource_class_id']
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# Data contributed by Workflow's Steps are in the
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# context['workflow'].context list. We can use that in the
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# template too.
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return context
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def _get_object(self, *args, **kwargs):
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# Data from URL are always in self.kwargs, we can use them here
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# to load our object of interest.
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resource_class_id = self.kwargs['resource_class_id']
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# Code omitted, this method should return some object obtained
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# from API.
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def get_initial(self):
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resource_class = self._get_object()
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# This data will be available in the Action's methods and
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# Workflow's handle method.
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# But only if the steps will depend on them.
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return {'resource_class_id': resource_class.id,
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'name': resource_class.name,
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'service_type': resource_class.service_type}
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#. In ``workflows.py`` we process the data, it is just more complex django
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form. ::
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class ResourcesAction(workflows.Action):
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# The name field will be automatically available in all action's
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# methods.
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# If we want this field to be used in the another Step or Workflow,
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# it has to be contributed by this step, then depend on in another
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# step.
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name = forms.CharField(max_length=255,
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label=_("Testing Name"),
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help_text="",
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required=True)
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def handle(self, request, data):
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pass
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# If we want to use some data from the URL, the Action's step
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# has to depend on them. It's then available in
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# self.initial['resource_class_id'] or data['resource_class_id'].
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# In other words, resource_class_id has to be passed by view's
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# get_initial and listed in step's depends_on list.
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# We can also use here the data from the other steps. If we want
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# the data from the other step, the step needs to contribute the
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# data and the steps needs to be ordered properly.
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class UpdateResources(workflows.Step):
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# This passes data from Workflow context to action methods
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# (handle, clean). Workflow context consists of URL data and data
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# contributed by other steps.
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depends_on = ("resource_class_id",)
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# By contributing, the data on these indexes will become available to
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# Workflow and to other Steps (if they will depend on them). Notice,
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# that the resources_object_ids key has to be manually added in
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# contribute method first.
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contributes = ("resources_object_ids", "name")
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def contribute(self, data, context):
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# We can obtain the http request from workflow.
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request = self.workflow.request
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if data:
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# Only fields defined in Action are automatically
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# available for contribution. If we want to contribute
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# something else, We need to override the contribute method
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# and manually add it to the dictionary.
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context["resources_object_ids"] =\
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request.POST.getlist("resources_object_ids")
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# We have to merge new context with the passed data or let
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# the superclass do this.
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context.update(data)
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return context
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class UpdateResourceClass(workflows.Workflow):
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default_steps = (UpdateResources,)
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def handle(self, request, data):
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pass
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# This method is called as last (after all Action's handle
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# methods). All data that are listed in step's 'contributes='
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# and 'depends_on=' are available here.
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# It can be easier to have the saving logic only here if steps
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# are heavily connected or complex.
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# data["resources_object_ids"], data["name"] and
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# data["resources_class_id"] are available here.
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