如果存在用户创建的方法实例，则显示它们，否则显示字符串 Django

Question

代码：

视图.py：

@login_required(login_url='loginPage')
def boardPage(request):
    if Board.objects.filter(user=request.user).exists():
        boards = get_list_or_404(Board, user=request.user)
        context = {'boards': boards}
        return render(request, 'tasks/boards.html', context)
    else:
        context = {'boards': False}
        return render(request, 'tasks/boards.html', context)

板。html：

{% extends 'tasks/main.html' %}
{% block content %}
    <center>board page<hr>
        <a href="{% url 'boardAdd' %}">add board</a> <br><br>
        your boards: <br> <br>
        {% if boards is false %}
            <p>you don't have any boards... Have you tried creating one? ;)</p>
        {% else %}
            {% for board in boards %}
                <a href="{% url 'insideBoard' board.id %}">{{board}}<br></a>
            {% endfor %}
        {% endif %}
        <br>
        <br>
        <hr>
        <a href="{% url 'logoutPage' %}">Logout</a>
    </center>
    {% if messages %}
        {% for message in messages %}
            <u><br>{% if message.tags %} {% endif %}>{{ message }}</u>
         {% endfor %}
    {% endif %}
{% endblock %}

模型.py：

class Board(models.Model):
    title = models.CharField(max_length=50, null=True)
    user = models.ForeignKey(User, null=True, on_delete=models.CASCADE)

    def __str__(self):
        return self.title

class Task(models.Model):
    title = models.CharField(max_length=200, null=True)
    done = models.BooleanField(default=False, null=True)
    created_at = models.DateTimeField(auto_now_add=True, null=True)
    user = models.ForeignKey(User, null=True, on_delete=models.CASCADE)
    board = models.ForeignKey(Board, null=True, on_delete=models.CASCADE)
    due_to = models.DateField(null=True, validators=[dateValidation])

    def __str__(self):
        return self.title

每次用户删除他/她的所有板或新用户访问该页面时（新用户还没有任何板，他们可以在那里创建一个）我得到“TypeError at / 'bool' object is not iterable” 如何我是否需要更改代码以在该页面上查看字符串而不是 class 的实例？

Answer 1

您不需要添加新变量，只需检查数组是否为空。 当您尝试在模板中迭代Boolean时遇到错误（ {'boards': False} ）

@login_required(login_url='loginPage')
def boardPage(request):
        boards = Board.objects.filter(user=request.user)
        context = {'boards': boards}
        return render(request, 'tasks/boards.html', context)

---

{% extends 'tasks/main.html' %}
{% block content %}
    <center>board page<hr>
        <a href="{% url 'boardAdd' %}">add board</a> <br><br>
        your boards: <br> <br>
        {% if not boards %}
            <p>you don't have any boards... Have you tried creating one? ;)</p>
        {% else %}
            {% for board in boards %}
                <a href="{% url 'insideBoard' board.id %}">{{board}}<br></a>
            {% endfor %}
        {% endif %}
        <br>
        <br>
        <hr>
        <a href="{% url 'logoutPage' %}">Logout</a>
    </center>
    {% if messages %}
        {% for message in messages %}
            <u><br>{% if message.tags %} {% endif %}>{{ message }}</u>
         {% endfor %}
    {% endif %}
{% endblock %}