Calculate free used accessory (#3621)

* Changed manufacturer and accessory_type - to be picked from table.

* repair make flake error.

* Added condition about release accessory to users.

* code style repair

* mysql error repair

* Calculate free/used accessory

* Calculate free/used accessory

* changed migrations

* changed release accessories.

* changed release accessories.

* changed migrations.

* flake fix

Co-authored-by: Szymon Jasinski <[email protected]>

src/ralph/accessories/admin.py

@@ -25,6 +25,7 @@ class AccessoryAdmin(TransitionAdminMixin, RalphAdmin):
     show_transition_history = True
     list_display = ['status', 'manufacturer', 'accessory_name',
                     'product_number', 'number_bought']
+    readonly_fields = ['used', 'free']
     list_select_related = ['owner']
     raw_id_fields = ['owner', 'region']
     list_filter = ['status', 'manufacturer', 'accessory_name',
@@ -39,7 +40,7 @@ class AccessoryAdmin(TransitionAdminMixin, RalphAdmin):
                 'fields': ('manufacturer', 'accessory_name',
                            'category', 'product_number',
                            'region', 'warehouse', 'number_bought',
-                           )
+                           'used', 'free',)
             }
         ),
         (

src/ralph/accessories/models.py

@@ -4,17 +4,53 @@
 from django.conf import settings
 from django.contrib.auth import get_user_model
 from django.db import models
+from django.db.models import Sum
+from django.utils.functional import cached_property
 from django.utils.translation import ugettext_lazy as _
 from mptt.fields import TreeForeignKey
 
 from ralph.accounts.models import RalphUser, Regionalizable
 from ralph.assets.models import Category, Manufacturer
 from ralph.back_office.models import Warehouse
 from ralph.lib.mixins.models import AdminAbsoluteUrlMixin, TimeStampMixin
+from ralph.lib.polymorphic.models import PolymorphicQuerySet
 from ralph.lib.transitions.decorators import transition_action
 from ralph.lib.transitions.fields import TransitionField
 from ralph.lib.transitions.models import TransitionWorkflowBaseWithPermissions
 
+_SELECT_USED_ACCESSORY_QUERY = """
+    SELECT COALESCE(SUM({assignment_table}.{quantity_column}), 0)
+    FROM {assignment_table}
+    WHERE {assignment_table}.{accessory_id_column} = {accessory_table}.{id_column} # noqa
+"""
+
+
+class AccessoryUsedFreeManager(models.Manager):
+    def get_queryset(self):
+        id_column = Accessory.baseobject_ptr.field.column
+
+        user_quantity_field = Accessory.users.through._meta.get_field('quantity') # noqa
+        user_accessory_field = Accessory.users.through._meta.get_field('accessory') # noqa
+        user_count_query = _SELECT_USED_ACCESSORY_QUERY.format(
+            assignment_table=Accessory.users.through._meta.db_table,
+            quantity_column=user_quantity_field.db_column or user_quantity_field.column,  # noqa
+            accessory_id_column=user_accessory_field.db_column or user_accessory_field,  # noqa
+            accessory_table=Accessory._meta.db_table,
+            id_column=id_column,
+        )
+
+        return super().get_queryset().extra(
+            select={
+                'user_count': user_count_query,
+            }
+        )
+
+
+class AccessoryUsedFreeRelatedObjectsManager(
+    AccessoryUsedFreeManager
+):
+    pass
+
 
 class AccessoryStatus(Choices):
     _ = Choices.Choice
@@ -122,6 +158,47 @@ def release_accessories(cls, instances, **kwargs):
             accessory_user.quantity += quantity
             accessory_user.save()
 
+    polymorphic_objects = PolymorphicQuerySet.as_manager()
+    objects_used_free = AccessoryUsedFreeManager()
+    objects_used_free_with_related = AccessoryUsedFreeRelatedObjectsManager()
+
+    def __str__(self):
+        return "{} x {} - ({})".format(
+            self.number_bought,
+            self.accessory_name,
+            self.product_number,
+        )
+
+    @cached_property
+    def autocomplete_str(self):
+        return "{} ({} free) x {} - ({})".format(
+            self.number_bought,
+            self.free,
+            self.accessory_name,
+            self.product_number,
+        )
+
+    @cached_property
+    def used(self):
+        if not self.pk:
+            return 0
+        try:
+            return (self.user_count or 0)
+        except AttributeError:
+            users_qs = self.user.through.objects.filter(accessory=self)
+
+            def get_sum(qs):
+                return qs.aggregate(sum=Sum('quantity'))['sum'] or 0
+            return sum(map(get_sum, [users_qs]))
+    used._permission_field = 'number_bought'
+
+    @cached_property
+    def free(self):
+        if not self.pk:
+            return 0
+        return self.number_bought - self.used
+    free._permission_field = 'number_bought'
+
 
 @reversion.register()
 class AccessoryUser(models.Model):