学习烧瓶：jinja2.exceptions.TemplateSyntaxError：预期的令牌'name'，得到'.'

Question

我正在学习 Flask，但我的代码无法运行，而且看起来还不错。我用谷歌搜索了这个错误并发现了非常不同的结果，所以对于 expected token 'name', got '.' 和其他符号来说是一个特定的结果。我正在测试 404 页面，它来自 base。

from flask import Flask, render_template                                                                 
from flask_bootstrap import Bootstrap

app = Flask(__name__)
bootstrap = Bootstrap(app)

@app.errorhandler(404)
def page_not_found(e):
    return render_template('404.html'), 404

@app.errorhandler(500)
def internal_server_error(e):
    return render_template('500.html'), 500

@app.route('/')
def index():
    return render_template('index.html')

app.add_url_rule('/', 'index', index)

@app.route('/user/<name>')
def user(name):
    return render_template('user.html', name=name)

base.html...

{% extends "bootstrap/base.html" %}

{% block title %}Flasky{% endblock %}

{% block navbar %}
<div class="navbar navbar-inverse" role="navigation">
        <div class="container">
                <div class="navbar-header">
                        <button type="button" class="navbar-toggle"
                         data-toggle="collapse" data-target=".navbar-collapse">
                                <span class="sr-only">Toggle Navigation</span>
                                <span class="icon-bar"></span>
                                <span class="icon-bar"></span>
                                <span class="icon-bar"></span>
                        </button>
                        <a class="navbar-brand" href="/">Flasky</a>
                </div>
                <div class="navbar-collapse collapse">
                        <ul class="nav navbar-nav">
                                <li><a href="/">Home</a></li>
                        </ul>
                </div>
        </div>
</div>
{% endblock %}

{% block content %}
<div class="container">
        {% block.page_content %}{% endblock %}
</div>
{% endblock %}

404.html...

{% extends "base.html" %}

{% block title %}Flasky - Page Not Found{% endblock %}

{% block page_content %}
<div class="page-header">
        <h1>Not Found!</h1>
</div>
{% endblock %}

当尝试请求一堆随机字母产生 404 时，会发生以下情况...

127.0.0.1 - - [21/Feb/2020 18:39:19] "GET /asdfsadf HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 1949, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 1925, in dispatch_request
    self.raise_routing_exception(req)
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 1907, in raise_routing_exception
    raise request.routing_exception
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/ctx.py", line 350, in match_request
    result = self.url_adapter.match(return_rule=True)
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/werkzeug/routing.py", line 1945, in match
    raise NotFound()
werkzeug.exceptions.NotFound: 404 Not Found: The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 2463, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 2449, in wsgi_app
    response = self.handle_exception(e)
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 1866, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 2446, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 1951, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 1815, in handle_user_exception
    return self.handle_http_exception(e)
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/app.py", line 1743, in handle_http_exception
    return handler(e)
  File "/home/john/devel/learn/flask/myflasky/hello.py", line 9, in page_not_found
    return render_template('404.html'), 404
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/templating.py", line 140, in render_template
    ctx.app,
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/flask/templating.py", line 120, in _render
    rv = template.render(context)
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/jinja2/environment.py", line 1090, in render
    self.environment.handle_exception()
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/jinja2/environment.py", line 832, in handle_exception
    reraise(*rewrite_traceback_stack(source=source))
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/jinja2/_compat.py", line 28, in reraise
    raise value.with_traceback(tb)
  File "/home/john/devel/learn/flask/myflasky/templates/404.html", line 1, in top-level template code
    {% extends "base.html" %}
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/jinja2/environment.py", line 832, in handle_exception
    reraise(*rewrite_traceback_stack(source=source))
  File "/home/john/devel/learn/flask/myflasky/venv/lib/python3.7/site-packages/jinja2/_compat.py", line 28, in reraise
    raise value.with_traceback(tb)
  File "/home/john/devel/learn/flask/myflasky/templates/base.html", line 29, in template
    {% block.page_content %}{% endblock %}
jinja2.exceptions.TemplateSyntaxError: expected token 'name', got '.'

我不明白如何找到这里报告的错误，也基本不明白输出。如果有人能给我指出这个错误的含义会很好，例如它期望“名称”在哪里，因为我不知道。

Answer 1

我查看了您的代码，首先注意到您访问的路线“/asdfsadf”不存在。您主要关心的应该是在您的“base.html”中，它应该是 {% block page_content %} 而不是 {% block.page_content %}。随便问什么！