refactor events

InvenTree/plugin/base/event/events.py

@@ -0,0 +1,239 @@
+"""
+Functions for triggering and responding to server side events
+"""
+
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+import logging
+
+from django.utils.translation import gettext_lazy as _
+
+from django.conf import settings
+from django.db import transaction
+from django.db.models.signals import post_save, post_delete
+from django.dispatch.dispatcher import receiver
+
+from common.models import InvenTreeSetting
+import common.notifications
+
+from InvenTree.ready import canAppAccessDatabase, isImportingData
+from InvenTree.tasks import offload_task
+
+from plugin.registry import registry
+
+
+logger = logging.getLogger('inventree')
+
+
+def trigger_event(event, *args, **kwargs):
+    """
+    Trigger an event with optional arguments.
+
+    This event will be stored in the database,
+    and the worker will respond to it later on.
+    """
+
+    if not settings.PLUGINS_ENABLED:
+        # Do nothing if plugins are not enabled
+        return
+
+    if not canAppAccessDatabase():
+        logger.debug(f"Ignoring triggered event '{event}' - database not ready")
+        return
+
+    logger.debug(f"Event triggered: '{event}'")
+
+    offload_task(
+        'plugin.events.register_event',
+        event,
+        *args,
+        **kwargs
+    )
+
+
+def register_event(event, *args, **kwargs):
+    """
+    Register the event with any interested plugins.
+
+    Note: This function is processed by the background worker,
+    as it performs multiple database access operations.
+    """
+
+    logger.debug(f"Registering triggered event: '{event}'")
+
+    # Determine if there are any plugins which are interested in responding
+    if settings.PLUGIN_TESTING or InvenTreeSetting.get_setting('ENABLE_PLUGINS_EVENTS'):
+
+        with transaction.atomic():
+
+            for slug, plugin in registry.plugins.items():
+
+                if plugin.mixin_enabled('events'):
+
+                    config = plugin.plugin_config()
+
+                    if config and config.active:
+
+                        logger.debug(f"Registering callback for plugin '{slug}'")
+
+                        # Offload a separate task for each plugin
+                        offload_task(
+                            'plugin.events.process_event',
+                            slug,
+                            event,
+                            *args,
+                            **kwargs
+                        )
+
+
+def process_event(plugin_slug, event, *args, **kwargs):
+    """
+    Respond to a triggered event.
+
+    This function is run by the background worker process.
+
+    This function may queue multiple functions to be handled by the background worker.
+    """
+
+    logger.info(f"Plugin '{plugin_slug}' is processing triggered event '{event}'")
+
+    plugin = registry.plugins.get(plugin_slug, None)
+
+    if plugin is None:
+        logger.error(f"Could not find matching plugin for '{plugin_slug}'")
+        return
+
+    plugin.process_event(event, *args, **kwargs)
+
+
+def allow_table_event(table_name):
+    """
+    Determine if an automatic event should be fired for a given table.
+    We *do not* want events to be fired for some tables!
+    """
+
+    if isImportingData():
+        # Prevent table events during the data import process
+        return False
+
+    table_name = table_name.lower().strip()
+
+    # Ignore any tables which start with these prefixes
+    ignore_prefixes = [
+        'account_',
+        'auth_',
+        'authtoken_',
+        'django_',
+        'error_',
+        'exchange_',
+        'otp_',
+        'plugin_',
+        'socialaccount_',
+        'user_',
+        'users_',
+    ]
+
+    if any([table_name.startswith(prefix) for prefix in ignore_prefixes]):
+        return False
+
+    ignore_tables = [
+        'common_notificationentry',
+        'common_webhookendpoint',
+        'common_webhookmessage',
+    ]
+
+    if table_name in ignore_tables:
+        return False
+
+    return True
+
+
+@receiver(post_save)
+def after_save(sender, instance, created, **kwargs):
+    """
+    Trigger an event whenever a database entry is saved
+    """
+
+    table = sender.objects.model._meta.db_table
+
+    instance_id = getattr(instance, 'id', None)
+
+    if instance_id is None:
+        return
+
+    if not allow_table_event(table):
+        return
+
+    if created:
+        trigger_event(
+            f'{table}.created',
+            id=instance.id,
+            model=sender.__name__,
+        )
+    else:
+        trigger_event(
+            f'{table}.saved',
+            id=instance.id,
+            model=sender.__name__,
+        )
+
+
+@receiver(post_delete)
+def after_delete(sender, instance, **kwargs):
+    """
+    Trigger an event whenever a database entry is deleted
+    """
+
+    table = sender.objects.model._meta.db_table
+
+    if not allow_table_event(table):
+        return
+
+    trigger_event(
+        f'{table}.deleted',
+        model=sender.__name__,
+    )
+
+
+def print_label(plugin_slug, label_image, label_instance=None, user=None):
+    """
+    Print label with the provided plugin.
+
+    This task is nominally handled by the background worker.
+
+    If the printing fails (throws an exception) then the user is notified.
+
+    Arguments:
+        plugin_slug: The unique slug (key) of the plugin
+        label_image: A PIL.Image image object to be printed
+    """
+
+    logger.info(f"Plugin '{plugin_slug}' is printing a label")
+
+    plugin = registry.plugins.get(plugin_slug, None)
+
+    if plugin is None:
+        logger.error(f"Could not find matching plugin for '{plugin_slug}'")
+        return
+
+    try:
+        plugin.print_label(label_image, width=label_instance.width, height=label_instance.height)
+    except Exception as e:
+        # Plugin threw an error - notify the user who attempted to print
+
+        ctx = {
+            'name': _('Label printing failed'),
+            'message': str(e),
+        }
+
+        logger.error(f"Label printing failed: Sending notification to user '{user}'")
+
+        # Throw an error against the plugin instance
+        common.notifications.trigger_notifaction(
+            plugin.plugin_config(),
+            'label.printing_failed',
+            targets=[user],
+            context=ctx,
+            delivery_methods=[common.notifications.UIMessageNotification]
+        )

InvenTree/plugin/base/event/mixins.py

@@ -0,0 +1,29 @@
+"""Plugin mixin class for events"""
+
+from plugin.helpers import MixinNotImplementedError
+
+
+class EventMixin:
+    """
+    Mixin that provides support for responding to triggered events.
+
+    Implementing classes must provide a "process_event" function:
+    """
+
+    def process_event(self, event, *args, **kwargs):
+        """
+        Function to handle events
+        Must be overridden by plugin
+        """
+        # Default implementation does not do anything
+        raise MixinNotImplementedError
+
+    class MixinMeta:
+        """
+        Meta options for this mixin
+        """
+        MIXIN_NAME = 'Events'
+
+    def __init__(self):
+        super().__init__()
+        self.add_mixin('events', True, __class__)

InvenTree/plugin/base/integration/mixins.py

@@ -238,32 +238,6 @@ class ScheduleMixin:
             logger.warning("unregister_tasks failed, database not ready")
 
 
-class EventMixin:
-    """
-    Mixin that provides support for responding to triggered events.
-
-    Implementing classes must provide a "process_event" function:
-    """
-
-    def process_event(self, event, *args, **kwargs):
-        """
-        Function to handle events
-        Must be overridden by plugin
-        """
-        # Default implementation does not do anything
-        raise MixinNotImplementedError
-
-    class MixinMeta:
-        """
-        Meta options for this mixin
-        """
-        MIXIN_NAME = 'Events'
-
-    def __init__(self):
-        super().__init__()
-        self.add_mixin('events', True, __class__)
-
-
 class UrlsMixin:
     """
     Mixin that enables custom URLs for the plugin