show email in order admin panel

shop/admin.py

@@ -47,11 +47,17 @@ class ShippingAddressAdmin(admin.ModelAdmin):
 
 @admin.register(Order)
 class OrderAdmin(admin.ModelAdmin):
-    list_display = ('id', 'date_ordered', 'status', 'total_price', 'get_shipping_address')
+    list_display = ('id', 'get_email', 'date_ordered', 'status', 'total_price', 'get_shipping_address')
     inlines = [OrderItemInline]
     list_filter = ('status', 'payment_status')
     readonly_fields = ('shipping_address_details',)
 
+    def get_email(self, obj):
+        if obj.guest_user:
+            return obj.guest_user.email
+        else:
+            return obj.user.email
+
     def get_shipping_address(self, obj):
         if obj.shipping_address:
             return f"{obj.shipping_address.street_address}, {obj.shipping_address.city}"