Django如果登录，则在模板中显示代码

# views.py
from django.contrib.auth import authenticate, login
from django.shortcuts import render, redirect

def login_view(request):
    if request.method == 'POST':
        username = request.POST['username']
        password = request.POST['password']
        user = authenticate(request, username=username, password=password)
        if user is not None:
            login(request, user)
            return redirect('home')
        else:
            error_message = 'Invalid username or password.'
    else:
        error_message = ''
    return render(request, 'login.html', {'error_message': error_message})

<!-- login.html -->
{% if error_message %}
    <p>{{ error_message }}</p>
{% endif %}
<form method="post" action="{% url 'login' %}">
    {% csrf_token %}
    <label for="username">Username:</label>
    <input type="text" id="username" name="username" required><br>
    <label for="password">Password:</label>
    <input type="password" id="password" name="password" required><br>
    <input type="submit" value="Login">
</form>