Update to report plugin API (#4649)

explicitly add the model instance when allowing plugins to add context data

InvenTree/plugin/base/integration/ReportMixin.py

@@ -22,13 +22,14 @@ class ReportMixin:
         super().__init__()
         self.add_mixin('report', True, __class__)
 
-    def add_report_context(self, instance, request, context):
+    def add_report_context(self, report_instance, model_instance, request, context):
         """Add extra context to the provided report instance.
 
         By default, this method does nothing.
 
         Args:
-            instance: The report instance to add context to
+            report_instance: The report instance to add context to
+            model_instance: The model instance which initiated the report generation
             request: The request object which initiated the report generation
             context: The context dictionary to add to
         """

InvenTree/plugin/samples/integration/report_plugin_sample.py

@@ -20,7 +20,7 @@ class SampleReportPlugin(ReportMixin, InvenTreePlugin):
         """Some custom function which is not required for the plugin to function"""
         return random.randint(0, 100)
 
-    def add_report_context(self, instance, request, context):
+    def add_report_context(self, report_instance, model_instance, request, context):
         """Add example content to the report instance"""
 
         # We can add any extra context data we want to the report
@@ -32,7 +32,7 @@ class SampleReportPlugin(ReportMixin, InvenTreePlugin):
         context['random_int'] = self.some_custom_function()
 
         # We can also add extra data to the context which is specific to the report type
-        context['is_purchase_order'] = isinstance(instance, PurchaseOrderReport)
+        context['is_purchase_order'] = isinstance(report_instance, PurchaseOrderReport)
 
         # We can also use the 'request' object to add extra context data
         context['request_method'] = request.method

InvenTree/report/models.py

@@ -217,7 +217,8 @@ class ReportTemplateBase(MetadataMixin, ReportBase):
         plugins = registry.with_mixin('report')
 
         for plugin in plugins:
-            plugin.add_report_context(self, request, context)
+            # Let each plugin add its own context data
+            plugin.add_report_context(self, self.object_to_print, request, context)
 
         return context