如何创建自定义验证方法来显示django表单中的错误

from django import forms

class MyForm(forms.Form):
    my_field = forms.CharField()

    def custom_validation(self, value):
        # 自定义验证逻辑
        if value != 'custom':
            raise forms.ValidationError('错误信息')

class MyForm(forms.Form):
    my_field = forms.CharField()

    def custom_validation(self, value):
        # 自定义验证逻辑
        if value != 'custom':
            raise forms.ValidationError('错误信息')

    def clean(self):
        cleaned_data = super().clean()
        my_field_value = cleaned_data.get('my_field')
        self.custom_validation(my_field_value)

from django.shortcuts import render
from .forms import MyForm

def my_view(request):
    if request.method == 'POST':
        form = MyForm(request.POST)
        if form.is_valid():
            # 表单验证通过
            # 执行其他逻辑
            pass
    else:
        form = MyForm()

    return render(request, 'my_template.html', {'form': form})

<form method="post">
  {% csrf_token %}
  {{ form.as_p }}
  <button type="submit">提交</button>
</form>

{% if form.errors %}
  <ul class="errorlist">
    {% for field in form %}
      {% for error in field.errors %}
        <li>{{ error }}</li>
      {% endfor %}
    {% endfor %}
  </ul>
{% endif %}