x/tuskar-ui
Code Issues Proposed changes

Fix the Resource Class creation error

Browse Source 
Had to clean up some of the horizon.workflows code we were carrying around.

Signed-off-by: Tomas Sedovic <tomas@sedovic.cz>
This commit is contained in:
Tomas Sedovic 2013-08-09 14:43:41 +02:00
parent 1839264f2a
commit 1b8705bedf
1 changed files with 15 additions and 815 deletions
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830
tuskar_ui/workflows.py
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@ -36,412 +36,14 @@ from horizon import base
from horizon import exceptions from horizon import exceptions
from horizon.templatetags.horizon import has_permissions from horizon.templatetags.horizon import has_permissions
from horizon.utils import html from horizon.utils import html
import horizon.workflows
LOG = logging.getLogger(__name__) LOG = logging.getLogger(__name__)
class WorkflowContext(dict):
def __init__(self, workflow, *args, **kwargs):
super(WorkflowContext, self).__init__(*args, **kwargs)
self._workflow = workflow
def __setitem__(self, key, val):
super(WorkflowContext, self).__setitem__(key, val)
return self._workflow._trigger_handlers(key)
def __delitem__(self, key):
return self.__setitem__(key, None)
def set(self, key, val):
return self.__setitem__(key, val)
def unset(self, key):
return self.__delitem__(key)
class ActionMetaclass(forms.forms.DeclarativeFieldsMetaclass):
def __new__(mcs, name, bases, attrs):
# Pop Meta for later processing
opts = attrs.pop("Meta", None)
# Create our new class
cls = super(ActionMetaclass, mcs).__new__(mcs, name, bases, attrs)
# Process options from Meta
cls.name = getattr(opts, "name", name)
cls.slug = getattr(opts, "slug", slugify(name))
cls.permissions = getattr(opts, "permissions", ())
cls.progress_message = getattr(opts,
"progress_message",
_("Processing..."))
cls.help_text = getattr(opts, "help_text", "")
cls.help_text_template = getattr(opts, "help_text_template", None)
return cls
class Action(forms.Form):
"""
An ``Action`` represents an atomic logical interaction you can have with
the system. This is easier to understand with a conceptual example: in the
context of a "launch instance" workflow, actions would include "naming
the instance", "selecting an image", and ultimately "launching the
instance".
Because ``Actions`` are always interactive, they always provide form
controls, and thus inherit from Django's ``Form`` class. However, they
have some additional intelligence added to them:
* ``Actions`` are aware of the permissions required to complete them.
* ``Actions`` have a meta-level concept of "help text" which is meant to be
displayed in such a way as to give context to the action regardless of
where the action is presented in a site or workflow.
* ``Actions`` understand how to handle their inputs and produce outputs,
much like :class:`~horizon.forms.SelfHandlingForm` does now.
``Action`` classes may define the following attributes in a ``Meta``
class within them:
.. attribute:: name
The verbose name for this action. Defaults to the name of the class.
.. attribute:: slug
A semi-unique slug for this action. Defaults to the "slugified" name
of the class.
.. attribute:: permissions
A list of permission names which this action requires in order to be
completed. Defaults to an empty list (``[]``).
.. attribute:: help_text
A string of simple help text to be displayed alongside the Action's
fields.
.. attribute:: help_text_template
A path to a template which contains more complex help text to be
displayed alongside the Action's fields. In conjunction with
:meth:`~horizon.workflows.Action.get_help_text` method you can
customize your help text template to display practically anything.
"""
__metaclass__ = ActionMetaclass
def __init__(self, request, context, *args, **kwargs):
if request.method == "POST":
super(Action, self).__init__(request.POST, initial=context)
else:
super(Action, self).__init__(initial=context)
if not hasattr(self, "handle"):
raise AttributeError("The action %s must define a handle method."
% self.__class__.__name__)
self.request = request
self._populate_choices(request, context)
def __unicode__(self):
return force_unicode(self.name)
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self.slug)
def _populate_choices(self, request, context):
for field_name, bound_field in self.fields.items():
meth = getattr(self, "populate_%s_choices" % field_name, None)
if meth is not None and callable(meth):
bound_field.choices = meth(request, context)
def get_help_text(self, extra_context=None):
""" Returns the help text for this step. """
text = ""
extra_context = extra_context or {}
if self.help_text_template:
tmpl = template.loader.get_template(self.help_text_template)
context = template.RequestContext(self.request, extra_context)
text += tmpl.render(context)
else:
text += linebreaks(force_unicode(self.help_text))
return safe(text)
def add_error(self, message):
"""
Adds an error to the Action's Step based on API issues.
"""
self._get_errors()[NON_FIELD_ERRORS] = self.error_class([message])
def handle(self, request, context):
"""
Handles any requisite processing for this action. The method should
return either ``None`` or a dictionary of data to be passed to
:meth:`~horizon.workflows.Step.contribute`.
Returns ``None`` by default, effectively making it a no-op.
"""
return None
class Step(object):
"""
A step is a wrapper around an action which defines it's context in a
workflow. It knows about details such as:
* The workflow's context data (data passed from step to step).
* The data which must be present in the context to begin this step (the
step's dependencies).
* The keys which will be added to the context data upon completion of the
step.
* The connections between this step's fields and changes in the context
data (e.g. if that piece of data changes, what needs to be updated in
this step).
A ``Step`` class has the following attributes:
.. attribute:: action
The :class:`~horizon.workflows.Action` class which this step wraps.
.. attribute:: depends_on
A list of context data keys which this step requires in order to
begin interaction.
.. attribute:: contributes
A list of keys which this step will contribute to the workflow's
context data. Optional keys should still be listed, even if their
values may be set to ``None``.
.. attribute:: connections
A dictionary which maps context data key names to lists of callbacks.
The callbacks may be functions, dotted python paths to functions
which may be imported, or dotted strings beginning with ``"self"``
to indicate methods on the current ``Step`` instance.
.. attribute:: before
Another ``Step`` class. This optional attribute is used to provide
control over workflow ordering when steps are dynamically added to
workflows. The workflow mechanism will attempt to place the current
step before the step specified in the attribute.
.. attribute:: after
Another ``Step`` class. This attribute has the same purpose as
:meth:`~horizon.workflows.Step.before` except that it will instead
attempt to place the current step after the given step.
.. attribute:: help_text
A string of simple help text which will be prepended to the ``Action``
class' help text if desired.
.. attribute:: template_name
A path to a template which will be used to render this step. In
general the default common template should be used. Default:
``"horizon/common/_workflow_step.html"``.
.. attribute:: has_errors
A boolean value which indicates whether or not this step has any
errors on the action within it or in the scope of the workflow. This
attribute will only accurately reflect this status after validation
has occurred.
.. attribute:: slug
Inherited from the ``Action`` class.
.. attribute:: name
Inherited from the ``Action`` class.
.. attribute:: permissions
Inherited from the ``Action`` class.
"""
action_class = None
depends_on = ()
contributes = ()
connections = None
before = None
after = None
help_text = ""
template_name = "horizon/common/_workflow_step.html"
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self.slug)
def __unicode__(self):
return force_unicode(self.name)
def __init__(self, workflow):
super(Step, self).__init__()
self.workflow = workflow
cls = self.__class__.__name__
if not (self.action_class and issubclass(self.action_class, Action)):
raise AttributeError("You must specify an action for %s." % cls)
self.slug = self.action_class.slug
self.name = self.action_class.name
self.permissions = self.action_class.permissions
self.has_errors = False
self._handlers = {}
if self.connections is None:
# We want a dict, but don't want to declare a mutable type on the
# class directly.
self.connections = {}
# Gather our connection handlers and make sure they exist.
for key, handlers in self.connections.items():
self._handlers[key] = []
# TODO(gabriel): This is a poor substitute for broader handling
if not isinstance(handlers, (list, tuple)):
raise TypeError("The connection handlers for %s must be a "
"list or tuple." % cls)
for possible_handler in handlers:
if callable(possible_handler):
# If it's callable we know the function exists and is valid
self._handlers[key].append(possible_handler)
continue
elif not isinstance(possible_handler, basestring):
return TypeError("Connection handlers must be either "
"callables or strings.")
bits = possible_handler.split(".")
if bits[0] == "self":
root = self
for bit in bits[1:]:
try:
root = getattr(root, bit)
except AttributeError:
raise AttributeError("The connection handler %s "
"could not be found on %s."
% (possible_handler, cls))
handler = root
elif len(bits) == 1:
# Import by name from local module not supported
raise ValueError("Importing a local function as a string "
"is not supported for the connection "
"handler %s on %s."
% (possible_handler, cls))
else:
# Try a general import
module_name = ".".join(bits[:-1])
try:
mod = import_module(module_name)
handler = getattr(mod, bits[-1])
except ImportError:
raise ImportError("Could not import %s from the "
"module %s as a connection "
"handler on %s."
% (bits[-1], module_name, cls))
except AttributeError:
raise AttributeError("Could not import %s from the "
"module %s as a connection "
"handler on %s."
% (bits[-1], module_name, cls))
self._handlers[key].append(handler)
@property
def action(self):
if not getattr(self, "_action", None):
try:
# Hook in the action context customization.
workflow_context = dict(self.workflow.context)
context = self.prepare_action_context(self.workflow.request,
workflow_context)
self._action = self.action_class(self.workflow.request,
context)
except:
LOG.exception("Problem instantiating action class.")
raise
return self._action
def prepare_action_context(self, request, context):
"""
Allows for customization of how the workflow context is passed to the
action; this is the reverse of what "contribute" does to make the
action outputs sane for the workflow. Changes to the context are not
saved globally here. They are localized to the action.
Simply returns the unaltered context by default.
"""
return context
def get_id(self):
""" Returns the ID for this step. Suitable for use in HTML markup. """
return "%s__%s" % (self.workflow.slug, self.slug)
def _verify_contributions(self, context):
for key in self.contributes:
# Make sure we don't skip steps based on weird behavior of
# POST query dicts.
field = self.action.fields.get(key, None)
if field and field.required and not context.get(key):
context.pop(key, None)
failed_to_contribute = set(self.contributes)
failed_to_contribute -= set(context.keys())
if failed_to_contribute:
raise exceptions.WorkflowError("The following expected data was "
"not added to the workflow context "
"by the step %s: %s."
% (self.__class__,
failed_to_contribute))
return True
def contribute(self, data, context):
"""
Adds the data listed in ``contributes`` to the workflow's shared
context. By default, the context is simply updated with all the data
returned by the action.
Note that even if the value of one of the ``contributes`` keys is
not present (e.g. optional) the key should still be added to the
context with a value of ``None``.
"""
if data:
for key in self.contributes:
context[key] = data.get(key, None)
return context
def render(self):
""" Renders the step. """
step_template = template.loader.get_template(self.template_name)
extra_context = {"form": self.action,
"step": self}
# FIXME: TableStep:
if issubclass(self.__class__, TableStep):
extra_context.update(self.get_context_data(self.workflow.request))
context = template.RequestContext(self.workflow.request, extra_context)
return step_template.render(context)
def get_help_text(self):
""" Returns the help text for this step. """
text = linebreaks(force_unicode(self.help_text))
text += self.action.get_help_text()
return safe(text)
def add_error(self, message):
"""
Adds an error to the Step based on API issues.
"""
self.action.add_error(message)
# FIXME: TableStep # FIXME: TableStep
class TableStep(Step): class TableStep(horizon.workflows.Step):
""" """
A :class:`~horizon.workflows.Step` class which knows how to deal with A :class:`~horizon.workflows.Step` class which knows how to deal with
:class:`~horizon.tables.DataTable` classes rendered inside of it. :class:`~horizon.tables.DataTable` classes rendered inside of it.
@ -475,6 +77,19 @@ class TableStep(Step):
self._tables = SortedDict(table_instances) self._tables = SortedDict(table_instances)
self._table_data_loaded = False self._table_data_loaded = False
def render(self):
""" Renders the step. """
step_template = template.loader.get_template(self.template_name)
extra_context = {"form": self.action,
"step": self}
# FIXME: TableStep:
if issubclass(self.__class__, TableStep):
extra_context.update(self.get_context_data(self.workflow.request))
context = template.RequestContext(self.workflow.request, extra_context)
return step_template.render(context)
def load_table_data(self): def load_table_data(self):
""" """
Calls the ``get_{{ table_name }}_data`` methods for each table class Calls the ``get_{{ table_name }}_data`` methods for each table class
@ -517,418 +132,3 @@ class TableStep(Step):
def has_more_data(self, table): def has_more_data(self, table):
return False return False
class WorkflowMetaclass(type):
def __new__(mcs, name, bases, attrs):
super(WorkflowMetaclass, mcs).__new__(mcs, name, bases, attrs)
attrs["_cls_registry"] = set([])
return type.__new__(mcs, name, bases, attrs)
class UpdateMembersStep(Step):
"""A step that allows a user to add/remove members from a group.
.. attribute:: show_roles
Set to False to disable the display of the roles dropdown.
.. attribute:: available_list_title
The title used for the available list column.
.. attribute:: members_list_title
The title used for the members list column.
.. attribute:: no_available_text
The placeholder text used when the available list is empty.
.. attribute:: no_members_text
The placeholder text used when the members list is empty.
"""
template_name = "horizon/common/_workflow_step_update_members.html"
show_roles = True
available_list_title = _("All available")
members_list_title = _("Members")
no_available_text = _("None available.")
no_members_text = _("No members.")
class Workflow(html.HTMLElement):
"""
A Workflow is a collection of Steps. It's interface is very
straightforward, but it is responsible for handling some very
important tasks such as:
* Handling the injection, removal, and ordering of arbitrary steps.
* Determining if the workflow can be completed by a given user at runtime
based on all available information.
* Dispatching connections between steps to ensure that when context data
changes all the applicable callback functions are executed.
* Verifying/validating the overall data integrity and subsequently
triggering the final method to complete the workflow.
The ``Workflow`` class has the following attributes:
.. attribute:: name
The verbose name for this workflow which will be displayed to the user.
Defaults to the class name.
.. attribute:: slug
The unique slug for this workflow. Required.
.. attribute:: steps
Read-only access to the final ordered set of step instances for
this workflow.
.. attribute:: default_steps
A list of :class:`~horizon.workflows.Step` classes which serve as the
starting point for this workflow's ordered steps. Defaults to an empty
list (``[]``).
.. attribute:: finalize_button_name
The name which will appear on the submit button for the workflow's
form. Defaults to ``"Save"``.
.. attribute:: success_message
A string which will be displayed to the user upon successful completion
of the workflow. Defaults to
``"{{ workflow.name }} completed successfully."``
.. attribute:: failure_message
A string which will be displayed to the user upon failure to complete
the workflow. Defaults to ``"{{ workflow.name }} did not complete."``
.. attribute:: depends_on
A roll-up list of all the ``depends_on`` values compiled from the
workflow's steps.
.. attribute:: contributions
A roll-up list of all the ``contributes`` values compiled from the
workflow's steps.
.. attribute:: template_name
Path to the template which should be used to render this workflow.
In general the default common template should be used. Default:
``"horizon/common/_workflow.html"``.
.. attribute:: entry_point
The slug of the step which should initially be active when the
workflow is rendered. This can be passed in upon initialization of
the workflow, or set anytime after initialization but before calling
either ``get_entry_point`` or ``render``.
.. attribute:: redirect_param_name
The name of a parameter used for tracking the URL to redirect to upon
completion of the workflow. Defaults to ``"next"``.
.. attribute:: object
The object (if any) which this workflow relates to. In the case of
a workflow which creates a new resource the object would be the created
resource after the relevant creation steps have been undertaken. In
the case of a workflow which updates a resource it would be the
resource being updated after it has been retrieved.
"""
__metaclass__ = WorkflowMetaclass
slug = None
default_steps = ()
template_name = "horizon/common/_workflow.html"
finalize_button_name = _("Save")
success_message = _("%s completed successfully.")
failure_message = _("%s did not complete.")
redirect_param_name = "next"
multipart = False
_registerable_class = Step
def __unicode__(self):
return self.name
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self.slug)
def __init__(self, request=None, context_seed=None, entry_point=None,
*args, **kwargs):
super(Workflow, self).__init__(*args, **kwargs)
if self.slug is None:
raise AttributeError("The workflow %s must have a slug."
% self.__class__.__name__)
self.name = getattr(self, "name", self.__class__.__name__)
self.request = request
self.depends_on = set([])
self.contributions = set([])
self.entry_point = entry_point
self.object = None
# Put together our steps in order. Note that we pre-register
# non-default steps so that we can identify them and subsequently
# insert them in order correctly.
self._registry = dict([(step_class, step_class(self)) for step_class
in self.__class__._cls_registry
if step_class not in self.default_steps])
self._gather_steps()
# Determine all the context data we need to end up with.
for step in self.steps:
self.depends_on = self.depends_on | set(step.depends_on)
self.contributions = self.contributions | set(step.contributes)
# Initialize our context. For ease we can preseed it with a
# regular dictionary. This should happen after steps have been
# registered and ordered.
self.context = WorkflowContext(self)
context_seed = context_seed or {}
clean_seed = dict([(key, val)
for key, val in context_seed.items()
if key in self.contributions | self.depends_on])
self.context_seed = clean_seed
self.context.update(clean_seed)
if request and request.method == "POST":
for step in self.steps:
valid = step.action.is_valid()
# Be sure to use the CLEANED data if the workflow is valid.
if valid:
data = step.action.cleaned_data
else:
data = request.POST
self.context = step.contribute(data, self.context)
@property
def steps(self):
if getattr(self, "_ordered_steps", None) is None:
self._gather_steps()
return self._ordered_steps
def get_step(self, slug):
""" Returns the instantiated step matching the given slug. """
for step in self.steps:
if step.slug == slug:
return step
def _gather_steps(self):
ordered_step_classes = self._order_steps()
for default_step in self.default_steps:
self.register(default_step)
self._registry[default_step] = default_step(self)
self._ordered_steps = [self._registry[step_class]
for step_class in ordered_step_classes
if has_permissions(self.request.user,
self._registry[step_class])]
def _order_steps(self):
steps = list(copy.copy(self.default_steps))
additional = self._registry.keys()
for step in additional:
try:
min_pos = steps.index(step.after)
except ValueError:
min_pos = 0
try:
max_pos = steps.index(step.before)
except ValueError:
max_pos = len(steps)
if min_pos > max_pos:
raise exceptions.WorkflowError("The step %(new)s can't be "
"placed between the steps "
"%(after)s and %(before)s; the "
"step %(before)s comes before "
"%(after)s."
% {"new": additional,
"after": step.after,
"before": step.before})
steps.insert(max_pos, step)
return steps
def get_entry_point(self):
"""
Returns the slug of the step which the workflow should begin on.
This method takes into account both already-available data and errors
within the steps.
"""
# If we have a valid specified entry point, use it.
if self.entry_point:
if self.get_step(self.entry_point):
return self.entry_point
# Otherwise fall back to calculating the appropriate entry point.
for step in self.steps:
if step.has_errors:
return step.slug
try:
step._verify_contributions(self.context)
except exceptions.WorkflowError:
return step.slug
# If nothing else, just return the first step.
return self.steps[0].slug
def _trigger_handlers(self, key):
responses = []
handlers = [(step.slug, f) for step in self.steps
for f in step._handlers.get(key, [])]
for slug, handler in handlers:
responses.append((slug, handler(self.request, self.context)))
return responses
@classmethod
def register(cls, step_class):
""" Registers a :class:`~horizon.workflows.Step` with the workflow. """
if not inspect.isclass(step_class):
raise ValueError('Only classes may be registered.')
elif not issubclass(step_class, cls._registerable_class):
raise ValueError('Only %s classes or subclasses may be registered.'
% cls._registerable_class.__name__)
if step_class in cls._cls_registry:
return False
else:
cls._cls_registry.add(step_class)
return True
@classmethod
def unregister(cls, step_class):
"""
Unregisters a :class:`~horizon.workflows.Step` from the workflow.
"""
try:
cls._cls_registry.remove(step_class)
except KeyError:
raise base.NotRegistered('%s is not registered' % cls)
return cls._unregister(step_class)
def validate(self, context):
"""
Hook for custom context data validation. Should return a boolean
value or raise :class:`~horizon.exceptions.WorkflowValidationError`.
"""
return True
def is_valid(self):
"""
Verified that all required data is present in the context and
calls the ``validate`` method to allow for finer-grained checks
on the context data.
"""
missing = self.depends_on - set(self.context.keys())
if missing:
raise exceptions.WorkflowValidationError(
"Unable to complete the workflow. The values %s are "
"required but not present." % ", ".join(missing))
# Validate each step. Cycle through all of them to catch all errors
# in one pass before returning.
steps_valid = True
for step in self.steps:
if not step.action.is_valid():
steps_valid = False
step.has_errors = True
if not steps_valid:
return steps_valid
return self.validate(self.context)
def finalize(self):
"""
Finalizes a workflow by running through all the actions in order
and calling their ``handle`` methods. Returns ``True`` on full success,
or ``False`` for a partial success, e.g. there were non-critical
errors. (If it failed completely the function wouldn't return.)
"""
partial = False
for step in self.steps:
try:
data = step.action.handle(self.request, self.context)
if data is True or data is None:
continue
elif data is False:
partial = True
else:
self.context = step.contribute(data or {}, self.context)
except:
partial = True
exceptions.handle(self.request)
if not self.handle(self.request, self.context):
partial = True
return not partial
def handle(self, request, context):
"""
Handles any final processing for this workflow. Should return a boolean
value indicating success.
"""
return True
def get_success_url(self):
"""
Returns a URL to redirect the user to upon completion. By default it
will attempt to parse a ``success_url`` attribute on the workflow,
which can take the form of a reversible URL pattern name, or a
standard HTTP URL.
"""
try:
return urlresolvers.reverse(self.success_url)
except urlresolvers.NoReverseMatch:
return self.success_url
def format_status_message(self, message):
"""
Hook to allow customization of the message returned to the user
upon successful or unsuccessful completion of the workflow.
By default it simply inserts the workflow's name into the message
string.
"""
if "%s" in message:
return message % self.name
else:
return message
def render(self):
""" Renders the workflow. """
workflow_template = template.loader.get_template(self.template_name)
extra_context = {"workflow": self}
if self.request.is_ajax():
extra_context['modal'] = True
context = template.RequestContext(self.request, extra_context)
return workflow_template.render(context)
def get_absolute_url(self):
""" Returns the canonical URL for this workflow.
This is used for the POST action attribute on the form element
wrapping the workflow.
For convenience it defaults to the value of
``request.get_full_path()`` with any query string stripped off,
e.g. the path at which the workflow was requested.
"""
return self.request.get_full_path().partition('?')[0]
def add_error_to_step(self, message, slug):
"""
Adds an error to the workflow's Step with the
specifed slug based on API issues. This is useful
when you wish for API errors to appear as errors on
the form rather than using the messages framework.
"""
step = self.get_step(slug)
if step:
step.add_error(message)