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Divide by zero error with very low power feed values #3152

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opened 2025-12-29 18:26:09 +01:00 by adam · 6 comments
adam commented 2025-12-29 18:26:09 +01:00
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Originally created by @hSaria on GitHub (Jan 13, 2020).

Environment

  • Python version: 3.6.8
  • NetBox version: 2.6.11

Steps to Reproduce

  1. Create power feed with voltage, amperage, and max utilization set to 1
  2. Create device with a power port with no power attributes (e.g. maximum_draw) that connects to the power feed created in step 1
  3. Browse to the power feed details page

Expected Behavior

Page loads

Observed Behavior

ZeroDivisionError exception because the percentage calculation is using available_power which was rounded to 0 with

self.voltage * self.amperage * (self.max_utilization / 100) =
1            * 1             * 0.01                         = 0.01
Originally created by @hSaria on GitHub (Jan 13, 2020). ### Environment * Python version: 3.6.8 * NetBox version: 2.6.11 ### Steps to Reproduce 1. Create power feed with voltage, amperage, and max utilization set to 1 2. Create device with a power port with no power attributes (e.g. maximum_draw) that connects to the power feed created in step 1 3. Browse to the power feed details page ### Expected Behavior Page loads ### Observed Behavior `ZeroDivisionError` exception because the percentage calculation is using `available_power` which was rounded to 0 with ```python self.voltage * self.amperage * (self.max_utilization / 100) = 1 * 1 * 0.01 = 0.01 ```
adam added the type: bugstatus: accepted labels 2025-12-29 18:26:09 +01:00
adam closed this issue 2025-12-29 18:26:09 +01:00
adam commented 2025-12-29 18:26:10 +01:00
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@jeremystretch commented on GitHub (Jan 13, 2020):

I'm not able to replicate this on v2.6.11. The PowerFeed is created as expected:

PowerFeed

Can you post the full stack trace please?

@jeremystretch commented on GitHub (Jan 13, 2020): I'm not able to replicate this on v2.6.11. The PowerFeed is created as expected: ![PowerFeed](https://user-images.githubusercontent.com/13487278/72262901-d248f100-35e5-11ea-90a6-eaca9cca0a63.png) Can you post the full stack trace please?
adam commented 2025-12-29 18:26:10 +01:00
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@hSaria commented on GitHub (Jan 13, 2020):

Environment:


Request Method: GET
Request URL: http://netbox/dcim/power-feeds/2/

Django Version: 2.2.8
Python Version: 3.6.8
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.humanize',
 'cacheops',
 'corsheaders',
 'debug_toolbar',
 'django_filters',
 'django_tables2',
 'django_prometheus',
 'mptt',
 'rest_framework',
 'taggit',
 'taggit_serializer',
 'timezone_field',
 'circuits',
 'dcim',
 'ipam',
 'extras',
 'secrets',
 'tenancy',
 'users',
 'utilities',
 'virtualization',
 'drf_yasg']
Installed Middleware:
('debug_toolbar.middleware.DebugToolbarMiddleware',
 'django_prometheus.middleware.PrometheusBeforeMiddleware',
 'corsheaders.middleware.CorsMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.middleware.security.SecurityMiddleware',
 'utilities.middleware.ExceptionHandlingMiddleware',
 'utilities.middleware.LoginRequiredMiddleware',
 'utilities.middleware.APIVersionMiddleware',
 'extras.middleware.ObjectChangeMiddleware',
 'django_prometheus.middleware.PrometheusAfterMiddleware')


Template error:
In template /opt/netbox-2.6.11/netbox/templates/_base.html, error at line 0
   division by zero
   1 : {% load static %}
   2 : {% load helpers %}
   3 : <!DOCTYPE html>
   4 : <html lang="en">
   5 : <head>
   6 :     <title>{% block title %}Home{% endblock %} - NetBox</title>
   7 :     <link rel="stylesheet" href="{% static 'bootstrap-3.4.1-dist/css/bootstrap.min.css' %}">
   8 :     <link rel="stylesheet" href="{% static 'font-awesome-4.7.0/css/font-awesome.min.css' %}">
   9 :     <link rel="stylesheet" href="{% static 'jquery-ui-1.12.1/jquery-ui.css' %}">
   10 :     <link rel="stylesheet" href="{% static 'select2-4.0.5/css/select2.min.css' %}">


Traceback:

File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)

File "/usr/local/lib/python3.6/site-packages/django/contrib/auth/mixins.py" in dispatch
  85.         return super().dispatch(request, *args, **kwargs)

File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py" in dispatch
  97.         return handler(request, *args, **kwargs)

File "/opt/netbox-2.6.11/netbox/dcim/views.py" in get
  2373.             'powerfeed': powerfeed,

File "/usr/local/lib/python3.6/site-packages/django/shortcuts.py" in render
  36.     content = loader.render_to_string(template_name, context, request, using=using)

File "/usr/local/lib/python3.6/site-packages/django/template/loader.py" in render_to_string
  62.     return template.render(context, request)

File "/usr/local/lib/python3.6/site-packages/django/template/backends/django.py" in render
  61.             return self.template.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  171.                     return self._render(context)

File "/usr/local/lib/python3.6/site-packages/django/test/utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/loader_tags.py" in render
  150.             return compiled_parent._render(context)

File "/usr/local/lib/python3.6/site-packages/django/test/utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/loader_tags.py" in render
  62.                 result = block.nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/defaulttags.py" in render
  513.             return self.nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/defaulttags.py" in render
  309.                 return nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/library.py" in render
  213.         resolved_args, resolved_kwargs = self.get_resolved_arguments(context)

File "/usr/local/lib/python3.6/site-packages/django/template/library.py" in get_resolved_arguments
  177.         resolved_args = [var.resolve(context) for var in self.args]

File "/usr/local/lib/python3.6/site-packages/django/template/library.py" in <listcomp>
  177.         resolved_args = [var.resolve(context) for var in self.args]

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in resolve
  698.                 new_obj = func(obj, *arg_vals)

File "/opt/netbox-2.6.11/netbox/utilities/templatetags/helpers.py" in percentage
  192.     return round(x / y * 100)

Exception Type: ZeroDivisionError at /dcim/power-feeds/2/
Exception Value: division by zero
@hSaria commented on GitHub (Jan 13, 2020): ``` Environment: Request Method: GET Request URL: http://netbox/dcim/power-feeds/2/ Django Version: 2.2.8 Python Version: 3.6.8 Installed Applications: ['django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.messages', 'django.contrib.staticfiles', 'django.contrib.humanize', 'cacheops', 'corsheaders', 'debug_toolbar', 'django_filters', 'django_tables2', 'django_prometheus', 'mptt', 'rest_framework', 'taggit', 'taggit_serializer', 'timezone_field', 'circuits', 'dcim', 'ipam', 'extras', 'secrets', 'tenancy', 'users', 'utilities', 'virtualization', 'drf_yasg'] Installed Middleware: ('debug_toolbar.middleware.DebugToolbarMiddleware', 'django_prometheus.middleware.PrometheusBeforeMiddleware', 'corsheaders.middleware.CorsMiddleware', 'django.contrib.sessions.middleware.SessionMiddleware', 'django.middleware.common.CommonMiddleware', 'django.middleware.csrf.CsrfViewMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware', 'django.contrib.messages.middleware.MessageMiddleware', 'django.middleware.clickjacking.XFrameOptionsMiddleware', 'django.middleware.security.SecurityMiddleware', 'utilities.middleware.ExceptionHandlingMiddleware', 'utilities.middleware.LoginRequiredMiddleware', 'utilities.middleware.APIVersionMiddleware', 'extras.middleware.ObjectChangeMiddleware', 'django_prometheus.middleware.PrometheusAfterMiddleware') Template error: In template /opt/netbox-2.6.11/netbox/templates/_base.html, error at line 0 division by zero 1 : {% load static %} 2 : {% load helpers %} 3 : <!DOCTYPE html> 4 : <html lang="en"> 5 : <head> 6 : <title>{% block title %}Home{% endblock %} - NetBox</title> 7 : <link rel="stylesheet" href="{% static 'bootstrap-3.4.1-dist/css/bootstrap.min.css' %}"> 8 : <link rel="stylesheet" href="{% static 'font-awesome-4.7.0/css/font-awesome.min.css' %}"> 9 : <link rel="stylesheet" href="{% static 'jquery-ui-1.12.1/jquery-ui.css' %}"> 10 : <link rel="stylesheet" href="{% static 'select2-4.0.5/css/select2.min.css' %}"> Traceback: File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner 34. response = get_response(request) File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response 115. response = self.process_exception_by_middleware(e, request) File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response 113. response = wrapped_callback(request, *callback_args, **callback_kwargs) File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py" in view 71. return self.dispatch(request, *args, **kwargs) File "/usr/local/lib/python3.6/site-packages/django/contrib/auth/mixins.py" in dispatch 85. return super().dispatch(request, *args, **kwargs) File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py" in dispatch 97. return handler(request, *args, **kwargs) File "/opt/netbox-2.6.11/netbox/dcim/views.py" in get 2373. 'powerfeed': powerfeed, File "/usr/local/lib/python3.6/site-packages/django/shortcuts.py" in render 36. content = loader.render_to_string(template_name, context, request, using=using) File "/usr/local/lib/python3.6/site-packages/django/template/loader.py" in render_to_string 62. return template.render(context, request) File "/usr/local/lib/python3.6/site-packages/django/template/backends/django.py" in render 61. return self.template.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render 171. return self._render(context) File "/usr/local/lib/python3.6/site-packages/django/test/utils.py" in instrumented_test_render 96. return self.nodelist.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render 937. bit = node.render_annotated(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated 904. return self.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/loader_tags.py" in render 150. return compiled_parent._render(context) File "/usr/local/lib/python3.6/site-packages/django/test/utils.py" in instrumented_test_render 96. return self.nodelist.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render 937. bit = node.render_annotated(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated 904. return self.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/loader_tags.py" in render 62. result = block.nodelist.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render 937. bit = node.render_annotated(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated 904. return self.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/defaulttags.py" in render 513. return self.nodelist.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render 937. bit = node.render_annotated(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated 904. return self.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/defaulttags.py" in render 309. return nodelist.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render 937. bit = node.render_annotated(context) File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated 904. return self.render(context) File "/usr/local/lib/python3.6/site-packages/django/template/library.py" in render 213. resolved_args, resolved_kwargs = self.get_resolved_arguments(context) File "/usr/local/lib/python3.6/site-packages/django/template/library.py" in get_resolved_arguments 177. resolved_args = [var.resolve(context) for var in self.args] File "/usr/local/lib/python3.6/site-packages/django/template/library.py" in <listcomp> 177. resolved_args = [var.resolve(context) for var in self.args] File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in resolve 698. new_obj = func(obj, *arg_vals) File "/opt/netbox-2.6.11/netbox/utilities/templatetags/helpers.py" in percentage 192. return round(x / y * 100) Exception Type: ZeroDivisionError at /dcim/power-feeds/2/ Exception Value: division by zero ```
adam commented 2025-12-29 18:26:10 +01:00
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@hSaria commented on GitHub (Jan 13, 2020):

@jeremystretch Yeah, I just tried to recreate this with a new database and it doesn't occur. Let me see what I did differently.

@hSaria commented on GitHub (Jan 13, 2020): @jeremystretch Yeah, I just tried to recreate this with a new database and it doesn't occur. Let me see what I did differently.
adam commented 2025-12-29 18:26:10 +01:00
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@hSaria commented on GitHub (Jan 13, 2020):

@jeremystretch updated the steps.

@hSaria commented on GitHub (Jan 13, 2020): @jeremystretch updated the steps.
adam commented 2025-12-29 18:26:11 +01:00
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@hSaria commented on GitHub (Jan 14, 2020):

@jeremystretch so I found out that this is also happening on the devices view (assign one of the power ports to a power feed. Shall I just keep chasing those down with if conditions or just change the percentage filter to return 0 if the denominator is 0?

Math people, please don't hurt me. I know diving by 0 is not equal to 0; just trying to avoid an exception here.

@hSaria commented on GitHub (Jan 14, 2020): @jeremystretch so I found out that this is also happening on the devices view (assign one of the power ports to a power feed. Shall I just keep chasing those down with if conditions or just change the percentage filter to return 0 if the denominator is 0? > Math people, please don't hurt me. I know diving by 0 is not equal to 0; just trying to avoid an exception here.
adam commented 2025-12-29 18:26:11 +01:00
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@jeremystretch commented on GitHub (Jan 14, 2020):

@hSaria Let's try to catch all the occurrences. IMO I think I'd rather know when we're dividing by zero than suppress the error.

@jeremystretch commented on GitHub (Jan 14, 2020): @hSaria Let's try to catch all the occurrences. IMO I think I'd rather know when we're dividing by zero than suppress the error.
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Reference: starred/netbox#3152
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