在clean()期间修改Django表单字段的值

from django import forms

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

    def clean(self):
        cleaned_data = super().clean()
        my_field_value = cleaned_data.get('my_field')
        # 修改字段值
        cleaned_data['my_field'] = my_field_value.upper()
        return cleaned_data

from django import forms

class MyForm(forms.Form):
    my_field = forms.CharField(widget=forms.TextInput(attrs={'value': 'default_value'}))

<form method="post">
    {% csrf_token %}
    {% for field in form %}
        {% if field.name == 'my_field' %}
            {{ field.label_tag }}
            {{ field|attr:"value:new_value" }}
        {% else %}
            {{ field }}
        {% endif %}
    {% endfor %}
   <button type="submit">Submit</button>
</form>