from decimal import Decimal as D
from django.utils.translation import gettext_lazy as _
from oscar.apps.order import exceptions
[docs]class EventHandler(object):
"""
Handle requested order events.
This is an important class: it houses the core logic of your shop's order
processing pipeline.
"""
def __init__(self, user=None, **kwargs):
self.user = user
self.kwargs = kwargs
# Core API
# --------
[docs] def handle_shipping_event(
self, order, event_type, lines, line_quantities, **kwargs
):
"""
Handle a shipping event for a given order.
This is most common entry point to this class - most of your order
processing should be modelled around shipping events. Shipping events
can be used to trigger payment and communication events.
You will generally want to override this method to implement the
specifics of you order processing pipeline.
"""
# Example implementation
self.validate_shipping_event(
order, event_type, lines, line_quantities, **kwargs
)
return self.create_shipping_event(
order, event_type, lines, line_quantities, **kwargs
)
[docs] def handle_payment_event(
self, order, event_type, amount, lines=None, line_quantities=None, **kwargs
):
"""
Handle a payment event for a given order.
These should normally be called as part of handling a shipping event.
It is rare to call to this method directly. It does make sense for
refunds though where the payment event may be unrelated to a particular
shipping event and doesn't directly correspond to a set of lines.
"""
self.validate_payment_event(
order, event_type, amount, lines, line_quantities, **kwargs
)
return self.create_payment_event(
order, event_type, amount, lines, line_quantities, **kwargs
)
[docs] def handle_order_status_change(self, order, new_status, note_msg=None):
"""
Handle a requested order status change
This method is not normally called directly by client code. The main
use-case is when an order is cancelled, which in some ways could be
viewed as a shipping event affecting all lines.
"""
order.set_status(new_status)
if note_msg:
self.create_note(order, note_msg)
# Validation methods
# ------------------
# pylint: disable=unused-argument
[docs] def validate_shipping_event(
self, order, event_type, lines, line_quantities, **kwargs
):
"""
Test if the requested shipping event is permitted.
If not, raise InvalidShippingEvent
"""
errors = []
for line, qty in zip(lines, line_quantities):
# The core logic should be in the model. Ensure you override
# 'is_shipping_event_permitted' and enforce the correct order of
# shipping events.
if not line.is_shipping_event_permitted(event_type, qty):
msg = _("The selected quantity for line #%(line_id)s is too large") % {
"line_id": line.id
}
errors.append(msg)
if errors:
raise exceptions.InvalidShippingEvent(", ".join(errors))
# pylint: disable=unused-argument
def validate_payment_event(
self, order, event_type, amount, lines=None, line_quantities=None, **kwargs
):
if lines and line_quantities:
errors = []
for line, qty in zip(lines, line_quantities):
if not line.is_payment_event_permitted(event_type, qty):
msg = _(
"The selected quantity for line #%(line_id)s is too large"
) % {"line_id": line.id}
errors.append(msg)
if errors:
raise exceptions.InvalidPaymentEvent(", ".join(errors))
# Query methods
# -------------
# These are to help determine the status of lines
[docs] def have_lines_passed_shipping_event(
self, order, lines, line_quantities, event_type
):
"""
Test whether the passed lines and quantities have been through the
specified shipping event.
This is useful for validating if certain shipping events are allowed
(i.e. you can't return something before it has shipped).
"""
for line, line_qty in zip(lines, line_quantities):
if line.shipping_event_quantity(event_type) < line_qty:
return False
return True
# Payment stuff
# -------------
[docs] def calculate_payment_event_subtotal(self, event_type, lines, line_quantities):
"""
Calculate the total charge for the passed event type, lines and line
quantities.
This takes into account the previous prices that have been charged for
this event.
Note that shipping is not including in this subtotal. You need to
subclass and extend this method if you want to include shipping costs.
"""
total = D("0.00")
for line, qty_to_consume in zip(lines, line_quantities):
# This part is quite fiddly. We need to skip the prices that have
# already been settled. This involves keeping a load of counters.
# Count how many of this line have already been involved in an
# event of this type.
qty_to_skip = line.payment_event_quantity(event_type)
# Test if request is sensible
if qty_to_skip + qty_to_consume > line.quantity:
raise exceptions.InvalidPaymentEvent
# Consume prices in order of ID (this is the default but it's
# better to be explicit)
qty_consumed = 0
for price in line.prices.all().order_by("id"):
if qty_consumed == qty_to_consume:
# We've accounted for the asked-for quantity: we're done
break
qty_available = price.quantity - qty_to_skip
if qty_available <= 0:
# Skip the whole quantity of this price instance
qty_to_skip -= price.quantity
else:
# Need to account for some of this price instance and
# track how many we needed to skip and how many we settled
# for.
qty_to_include = min(qty_to_consume - qty_consumed, qty_available)
total += qty_to_include * price.price_incl_tax
# There can't be any left to skip if we've included some in
# our total
qty_to_skip = 0
qty_consumed += qty_to_include
return total
# Stock
# -----
[docs] def are_stock_allocations_available(self, lines, line_quantities):
"""
Check whether stock records still have enough stock to honour the
requested allocations.
Lines whose product doesn't track stock are disregarded, which means
this method will return True if only non-stock-tracking-lines are
passed.
This means you can just throw all order lines to this method, without
checking whether stock tracking is enabled or not.
This is okay, as calling consume_stock_allocations() has no effect for
non-stock-tracking lines.
"""
for line, qty in zip(lines, line_quantities):
record = line.stockrecord
if not record:
return False
if not record.can_track_allocations:
continue
if not record.is_allocation_consumption_possible(qty):
return False
return True
[docs] def consume_stock_allocations(self, order, lines=None, line_quantities=None):
"""
Consume the stock allocations for the passed lines.
If no lines/quantities are passed, do it for all lines.
"""
if not lines:
lines = order.lines.all()
if not line_quantities:
line_quantities = [line.quantity for line in lines]
for line, qty in zip(lines, line_quantities):
if line.stockrecord:
line.stockrecord.consume_allocation(qty)
[docs] def cancel_stock_allocations(self, order, lines=None, line_quantities=None):
"""
Cancel the stock allocations for the passed lines.
If no lines/quantities are passed, do it for all lines.
"""
if not lines:
lines = order.lines.all()
if not line_quantities:
line_quantities = [line.quantity for line in lines]
for line, qty in zip(lines, line_quantities):
if line.stockrecord:
line.stockrecord.cancel_allocation(qty)
# Model instance creation
# -----------------------
def create_shipping_event(
self, order, event_type, lines, line_quantities, **kwargs
):
reference = kwargs.get("reference", "")
event = order.shipping_events.create(event_type=event_type, notes=reference)
try:
for line, quantity in zip(lines, line_quantities):
event.line_quantities.create(line=line, quantity=quantity)
except exceptions.InvalidShippingEvent:
event.delete()
raise
return event
def create_payment_event(
self, order, event_type, amount, lines=None, line_quantities=None, **kwargs
):
reference = kwargs.get("reference", "")
event = order.payment_events.create(
event_type=event_type, amount=amount, reference=reference
)
if lines and line_quantities:
for line, quantity in zip(lines, line_quantities):
event.line_quantities.create(line=line, quantity=quantity)
return event
def create_communication_event(self, order, event_type):
return order.communication_events.create(event_type=event_type)
def create_note(self, order, message, note_type="System"):
return order.notes.create(message=message, note_type=note_type, user=self.user)