Fixed #33864 -- Deprecated length_is template filter.

2 files changed, 11 insertions, 4 deletions

diff --git a/django/contrib/admin/templates/admin/includes/fieldset.html b/django/contrib/admin/templates/admin/includes/fieldset.html
index 8207d47ec4..ba260a36ce 100644
--- a/django/contrib/admin/templates/admin/includes/fieldset.html
+++ b/django/contrib/admin/templates/admin/includes/fieldset.html
@@ -4,11 +4,11 @@
         <div class="description">{{ fieldset.description|safe }}</div>
     {% endif %}
     {% for line in fieldset %}
-        <div class="form-row{% if line.fields|length_is:'1' and line.errors %} errors{% endif %}{% if not line.has_visible_field %} hidden{% endif %}{% for field in line %}{% if field.field.name %} field-{{ field.field.name }}{% endif %}{% endfor %}">
-            {% if line.fields|length_is:'1' %}{{ line.errors }}{% endif %}
+        <div class="form-row{% if line.fields|length == 1 and line.errors %} errors{% endif %}{% if not line.has_visible_field %} hidden{% endif %}{% for field in line %}{% if field.field.name %} field-{{ field.field.name }}{% endif %}{% endfor %}">
+            {% if line.fields|length == 1 %}{{ line.errors }}{% endif %}
             {% for field in line %}
-                <div{% if not line.fields|length_is:'1' %} class="fieldBox{% if field.field.name %} field-{{ field.field.name }}{% endif %}{% if not field.is_readonly and field.errors %} errors{% endif %}{% if field.field.is_hidden %} hidden{% endif %}"{% elif field.is_checkbox %} class="checkbox-row"{% endif %}>
-                    {% if not line.fields|length_is:'1' and not field.is_readonly %}{{ field.errors }}{% endif %}
+                <div{% if not line.fields|length == 1 %} class="fieldBox{% if field.field.name %} field-{{ field.field.name }}{% endif %}{% if not field.is_readonly and field.errors %} errors{% endif %}{% if field.field.is_hidden %} hidden{% endif %}"{% elif field.is_checkbox %} class="checkbox-row"{% endif %}>
+                    {% if not line.fields|length == 1 and not field.is_readonly %}{{ field.errors }}{% endif %}
                     {% if field.is_checkbox %}
                         {{ field.field }}{{ field.label_tag }}
                     {% else %}
diff --git a/django/template/defaultfilters.py b/django/template/defaultfilters.py
index 46334791c6..7a5b28d159 100644
--- a/django/template/defaultfilters.py
+++ b/django/template/defaultfilters.py
@@ -2,6 +2,7 @@
 import random as random_module
 import re
 import types
+import warnings
 from decimal import ROUND_HALF_UP, Context, Decimal, InvalidOperation
 from functools import wraps
 from inspect import unwrap
@@ -11,6 +12,7 @@ from urllib.parse import quote
 
 from django.utils import formats
 from django.utils.dateformat import format, time_format
+from django.utils.deprecation import RemovedInDjango51Warning
 from django.utils.encoding import iri_to_uri
 from django.utils.html import avoid_wrapping, conditional_escape, escape, escapejs
 from django.utils.html import json_script as _json_script
@@ -611,6 +613,11 @@ def length(value):
 @register.filter(is_safe=False)
 def length_is(value, arg):
     """Return a boolean of whether the value's length is the argument."""
+    warnings.warn(
+        "The length_is template filter is deprecated in favor of the length template "
+        "filter and the == operator within an {% if %} tag.",
+        RemovedInDjango51Warning,
+    )
     try:
         return len(value) == int(arg)
     except (ValueError, TypeError):