python - 如何正确使用 Jinja2 计数/长度而不会出错？

Question

我的模板中有这个:

<h2>
    Users ({{ users|length }})
</h2>

我还有一个显示用户行的循环:

    {% for user in users %}    
    <tr>
        <td>
            {{ user.email }}
            etc...
        </td>
    </tr>
    {% endfor %}

我看不出我做错了什么。用户表工作得很好。但是当我用长度过滤器添加 h2 时，我得到这个错误:

Traceback (most recent call last):
  File "/Users/sean/Projects/appcash.me/_git/www/bottle.py", line 856, in _handle
    return route.call(**args)
  File "/Users/sean/Projects/appcash.me/_git/www/bottle.py", line 1721, in wrapper
    rv = callback(*a, **ka)
  File "/Users/sean/Projects/appcash.me/_git/www/views/admin.py", line 27, in custom_admin_page
    return template('admin/users.html', users=users)
  File "/Users/sean/Projects/appcash.me/_git/www/bottle.py", line 3487, in template
    return TEMPLATES[tplid].render(kwargs)
  File "/Users/sean/Projects/appcash.me/_git/www/datafly/core.py", line 184, in render
    return self.tpl.render(**_defaults)
  File "/Users/sean/Projects/appcash.me/_git/venv/lib/python2.7/site-packages/jinja2/environment.py", line 969, in render
    return self.environment.handle_exception(exc_info, True)
  File "/Users/sean/Projects/appcash.me/_git/venv/lib/python2.7/site-packages/jinja2/environment.py", line 742, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "<template>", line 3, in top-level template code
  File "<template>", line 57, in top-level template code
  File "<template>", line 8, in block "content"
TypeError: object of type 'Cursor' has no len()

Answer 1

你可以试试这个:

{{ users.count() }}