解决Django表单验证失败后字段值清空的问题

# views.py
from django.shortcuts import render, redirect
from django.contrib.auth import login
from django.contrib import messages
from .forms import CustomUserCreationForm # 确保导入你的表单

def register_view(request):
    if request.method == 'POST':
        form = CustomUserCreationForm(request.POST) # 关键：将POST数据绑定到表单
        if form.is_valid():
            user = form.save()
            login(request, user)
            messages.success(request, f'{user.first_name}, 您的账户已成功创建！')
            return redirect('home')
        else:
            # 表单无效时，form对象仍然包含用户提交的数据和错误信息
            # 此时，将form对象传递给模板，以便正确渲染
            messages.error(request, '请修正以下错误：') # 可以在这里添加一个通用的错误提示
    else:
        form = CustomUserCreationForm() # GET请求时创建空表单

    return render(request, 'base/register.html', {'form': form})

<!-- 原始模板片段，直接使用<input>标签 -->
<div class="col-md-12">
  <input class="form-control" type="text" name="first_name" placeholder="Firstname" required>
  {% if form.first_name.errors %}
  {% for error in form.first_name.errors %}
  <span style="color:#DC3545;">{{error}}</span>
  {% endfor %}
  {% endif %}
</div>

<!-- 修正后的模板片段，使用Django表单字段渲染 -->
<form method="POST" class="requires-validation" novalidate>
    {% csrf_token %} {# 必须包含CSRF令牌 #}

    <div class="col-md-12">
        {# 使用 {{ form.first_name }} 渲染字段，它会自动填充值 #}
        {{ form.first_name }} 
        {% if form.first_name.errors %}
            {% for error in form.first_name.errors %}
                <span style="color:#DC3545;">{{ error }}</span>
            {% endfor %}
        {% endif %}
    </div>

    <div class="col-md-12">
        {{ form.last_name }}
        {% if form.last_name.errors %}
            {% for error in form.last_name.errors %}
                <span style="color:#DC3545;">{{ error }}</span>
            {% endfor %}
        {% endif %}
    </div>

    <div class="col-md-12">
        {{ form.email }}
        {% if form.email.errors %}
            {% for error in form.email.errors %}
                <span style="color:#DC3545;">{{ error }}</span>
            {% endfor %}
        {% endif %}
    </div>

    <div class="col-md-12">
        {{ form.password1 }}
        {% if form.password1.errors %}
            {% for error in form.password1.errors %}
                <span style="color:#DC3545;">{{ error }}</span>
            {% endfor %}
        {% endif %}
    </div>

    <div class="col-md-12">
        {{ form.password2 }}
        {% if form.password2.errors %}
            {% for error in form.password2.errors %}
                {# 对于确认密码字段，可以自定义错误信息 #}
                <span style="color:#DC3545;">密码不匹配，请确认并重试</span>
            {% endfor %}
        {% endif %}
    </div>

    <div class="form-button mt-3">
        <button id="submit" type="submit" class="btn btn-primary">注册</button>
    </div>
    <br>
    <span>已有账户？<a href="">登录</a></span>
</form>

# forms.py
from django import forms
from django.contrib.auth.forms import UserCreationForm, UserChangeForm
from .models import UserModel # 确保导入你的模型

class CustomUserCreationForm(UserCreationForm):
    first_name = forms.CharField(
        label='',
        widget=forms.TextInput(attrs={'class': 'form-control', 'placeholder': '名'})
    )

    last_name = forms.CharField(
        label='',
        widget=forms.TextInput(attrs={'class': 'form-control', 'placeholder': '姓'})
    )

    email = forms.CharField(
        label='',
        widget=forms.EmailInput(attrs={'class': 'form-control', 'placeholder': '邮箱'}) # 建议使用EmailInput
    )

    password1 = forms.CharField(
        label='',
        widget=forms.PasswordInput(attrs={'class': 'form-control', 'placeholder': '输入密码'})
    )

    password2 = forms.CharField(
        label='',
        widget=forms.PasswordInput(attrs={'class': 'form-control', 'placeholder': '再次输入密码'})
    )

    class Meta:
        model = UserModel
        fields = ('email', 'first_name', 'last_name') # 注意：password1和password2通常不直接在fields中列出，UserCreationForm会处理它们

    # 如果需要自定义密码匹配验证，可以在这里添加clean方法
    def clean(self):
        cleaned_data = super().clean()
        password = cleaned_data.get('password1')
        password_confirm = cleaned_data.get('password2')

        if password and password_confirm and password != password_confirm:
            self.add_error('password2', '两次输入的密码不一致。') # 为password2字段添加错误
        return cleaned_data

class CustomUserChangeForm(UserChangeForm):
    class Meta:
        model = UserModel
        fields = ('email', 'first_name', 'last_name')