A template filter for having more control over whitespace characters of text output

email.txt

{% load text_formatting %}

{% filter normalize_text %}
Hi {{ user.name }},

{% if order.is_urgent %}
⚠️ URGENT: Your order requires immediate attention!\n\n
{% endif %}

Your order #{{ order.id }} has been confirmed.\n
Items:\n
{% for item in order.items %}
\t- {{ item.name }} ({{ item.quantity }}x)\n
{% endfor %}

Total: ${{ order.total }}

Best regards,\n
{{ company.name }}
{% endfilter %}

text_formatting.py

# myproject/apps/core/templatetags/text_formatting.py

import re
from django import template

register = template.Library()


@register.filter(name='normalize_text')
def normalize_text(value):
    """
    Normalizes whitespace in text templates while preserving escaped sequences.
    Collapses multiple spaces/newlines but converts r"\n", r"\t", r"\r".
    """
    # Replace escaped sequences with placeholders
    placeholders = {}
    escaped_chars = {
        r'\n': '\n',
        r'\t': '\t',
        r'\r': '\r',
    }
    
    for i, (escaped, char) in enumerate(escaped_chars.items()):
        placeholder = f'\x00ESCAPED{i}\x00'
        placeholders[placeholder] = char
        value = value.replace(escaped, placeholder)
    
    # Normalize whitespace
    # Replace multiple spaces with single space
    value = re.sub(r' +', ' ', value)
    # Replace multiple newlines with double newline max
    value = re.sub(r'\n\n+', '\n\n', value)
    # Remove trailing/leading whitespace on each line
    value = '\n'.join(line.strip() for line in value.split('\n'))
    # Remove empty lines at start and end
    value = value.strip()
    
    # Restore escaped sequences
    for placeholder, char in placeholders.items():
        value = value.replace(placeholder, char)
    
    return value