Django-crispy-forms更改单选按钮错误呈现

Question

当为非单选按钮呈现错误时，我看到：

<div id="div_id_field_a" class="control-group error">
  <label for="id_field_a" class="control-label ">Field A</label>
  <div class="controls">
    <select class="select" id="id_field_a" name="field_a">
      <option value="" selected="selected"></option>
      <option value="0">0</option>
      <option value="1">1</option>
    </select>
    <span id="error_1_id_field_a" class="help-inline"><strong>Select one</strong></span>
  </div>
</div>

当为单选按钮呈现错误时，我看到了：

<div id="div_id_field_b" class="control-group error">
  <label for="id_field_b_0" class="control-label ">Field b</label>
  <div class="controls">
    <p id="error_1_id_field_b" class="help-block"><strong>Enter a value</strong></p>
    <label class="radio"><input type="radio" name="field_b" id="id_field_b_1" value="True">Yes</label>
    <label class="radio"> <input type="radio" name="field_b" id="id_field_b_2" value="False">No</label>
  </div>
</div>

如何在单选按钮控件之后显示错误消息，这是使用组合框时会发生什么？或者至少不会在p代码中呈现错误，而是在span代码中呈现错误？

以下是我如何呈现表单：

{% load crispy_forms_tags %}
<form id='main-form'>
  {% csrf_token %}
  {% crispy form form.helper %}
</form>

和表格：

class MyForm(ReoBaseForm):
  field_b = forms.ChoiceField(required=False, choices=((True, 'Yes'), (False, 'No')),
    label='Field b', widget=forms.RadioSelect())

  def __init__(self, *args, **kwargs):
    super(MyForm, self).__init__(*args, **kwargs)

    self.helper = FormHelper()
    self.helper.form_tag = False