如何在Django表单中添加truncatechars过滤器&

# forms.py
from django import forms

class ExampleForm(forms.Form):
    long_text = forms.CharField(widget=forms.Textarea)

<!-- template.html -->
<form method="post">
    {% csrf_token %}
    {{ form.long_text|truncatechars:50 }}
    <button type="submit">Submit</button>
</form>

{% load humanize %}

{{ form.long_text|length }} <!-- 打印字段长度 -->
{{ form.long_text|truncatechars:50 }} <!-- 应用过滤器 -->

# templatetags/custom_filters.py
from django import template

register = template.Library()

@register.filter
def custom_truncate(value, arg):
    try:
        length = int(arg)
    except ValueError:  # Invalid literal for int().
        return value  # Fail silently.
    if len(value) > length:
        return value[:length] + '...'
    return value

{% load custom_filters %}
{{ form.long_text|custom_truncate:50 }}