Jinja 2对于循环崩溃谷歌应用引擎

我有一个简单的Jinja模板测试片段，我为HTML模板编写，但由于某些原因，循环崩溃在线应用引擎和devappserver。我尝试用一个常量代替我的for循环的主题，以测试实际的循环，并根据Cloud SDK Shell错误消息将其隔离为for循环的实际语法。代码段出了什么问题？Jinja 2对于循环崩溃谷歌应用引擎

错误：

File "C:\Users\Skyler\Documents\Reverie\reflect\templates\index.html", 
line 9, 
in template 
    {{% for test in my_list %}} 
TemplateSyntaxError: unexpected '%'

的index.html

<!DOCTYPE html> 
<html> 
<head> 
    <title>{{title}}</title> 
</head> 
<body> 
<h1> {{my_list[3]}} </h1> 
<ul> 
    {{% for test in my_list %}} 
    <li>{{my_list[1]}}</li> 
    {{% endfor %}} 
</ul> 
</body> 
</html>

test.py

import webapp2 
import jinja2 
import os 

template_dir = os.path.join(os.path.dirname(__file__), "templates") 
jinja_env = jinja2.Environment(loader = jinja2.FileSystemLoader(template_dir), autoescape = True) 

class Handler(webapp2.RequestHandler): 
    def write(self, *a, **kw): 
     self.response.write(*a, **kw) 

    def render_str(self, template, **params): 
     t = jinja_env.get_template(template) 
     return t.render(params) 

    def render(self, template, **kw): 
     self.write(self.render_str(template, **kw)) 

class MainPage(Handler): 
    """docstring for MainPage""" 
    def get(self): 
     self.render("index.html", title="Nani", my_list=[0,1,2,"string"]) 

app = webapp2.WSGIApplication([('/', MainPage),], debug=True)

的app.yaml

runtime: python27 
api_version: 1 
threadsafe: true 

handlers: 
- url:/
    script: test.app 

libraries: 
- name: jinja2 
    version: latest

Full Stacktrace

ERROR 2017-07-18 05:02:36,960 webapp2.py:1528] unexpected '%' 
Traceback (most recent call last): 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 1511, in __call__ 
    rv = self.handle_exception(request, response, e) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 1505, in __call__ 
    rv = self.router.dispatch(request, response) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 1253, in default_dispatcher 
    return route.handler_adapter(request, response) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 1077, in __call__ 
    return handler.dispatch() 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 547, in dispatch 
    return self.handle_exception(e, self.app.debug) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 545, in dispatch 
    return method(*args, **kwargs) 
    File "C:\Users\Skyler\Documents\Reverie\reflect\test.py", line 22, in get 
    self.render("index.html", title="Nani", my_list=[0,1,2,"string"]) 
    File "C:\Users\Skyler\Documents\Reverie\reflect\test.py", line 17, in render 
    self.write(self.render_str(template, **kw)) 
    File "C:\Users\Skyler\Documents\Reverie\reflect\test.py", line 13, in render_s 
tr 
    t = jinja_env.get_template(template) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\jinja2-2.6\jinja2\environment.py", line 719, in get_templa 
te 
    return self._load_template(name, self.make_globals(globals)) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\jinja2-2.6\jinja2\environment.py", line 693, in _load_temp 
late 
    template = self.loader.load(self, name, globals) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\jinja2-2.6\jinja2\loaders.py", line 127, in load 
    code = environment.compile(source, name, filename) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\jinja2-2.6\jinja2\environment.py", line 493, in compile 
    self.handle_exception(exc_info, source_hint=source) 
    File "C:\Users\Skyler\Documents\Reverie\reflect\templates\index.html", line 9, 
in template 
    {{% for test in my_list %}} 
TemplateSyntaxError: unexpected '%' 
ERROR 2017-07-18 05:02:36,960 wsgi.py:279] 
Traceback (most recent call last): 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\google\appengine\runtime\wsgi.py", line 267, in Handle 
    result = handler(dict(self._environ), self._StartResponse) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 1519, in __call__ 
    response = self._internal_error(e) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 1511, in __call__ 
    rv = self.handle_exception(request, response, e) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 1505, in __call__ 
    rv = self.router.dispatch(request, response) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 1253, in default_dispatcher 
    return route.handler_adapter(request, response) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 1077, in __call__ 
    return handler.dispatch() 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 547, in dispatch 
    return self.handle_exception(e, self.app.debug) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\webapp2-2.3\webapp2.py", line 545, in dispatch 
    return method(*args, **kwargs) 
    File "C:\Users\Skyler\Documents\Reverie\reflect\test.py", line 22, in get 
    self.render("index.html", title="Nani", my_list=[0,1,2,"string"]) 
    File "C:\Users\Skyler\Documents\Reverie\reflect\test.py", line 17, in render 
    self.write(self.render_str(template, **kw)) 
    File "C:\Users\Skyler\Documents\Reverie\reflect\test.py", line 13, in render_s 
tr 
    t = jinja_env.get_template(template) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\jinja2-2.6\jinja2\environment.py", line 719, in get_templa 
te 
    return self._load_template(name, self.make_globals(globals)) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\jinja2-2.6\jinja2\environment.py", line 693, in _load_temp 
late 
    template = self.loader.load(self, name, globals) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\jinja2-2.6\jinja2\loaders.py", line 127, in load 
    code = environment.compile(source, name, filename) 
    File "C:\Users\Skyler\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform 
\google_appengine\lib\jinja2-2.6\jinja2\environment.py", line 493, in compile 
    self.handle_exception(exc_info, source_hint=source) 
    File "C:\Users\Skyler\Documents\Reverie\reflect\templates\index.html", line 9, 
in template 
    {{% for test in my_list %}} 
TemplateSyntaxError: unexpected '%' 
INFO  2017-07-17 22:02:36,970 module.py:832] default: "GET/HTTP/1.1" 500 -

来源

2017-07-18 Skyler

这可能是因为您似乎太多地使用了一个花括号。看看从docs循环：

<title>{% block title %}{% endblock %}</title> <ul> {% for user in users %} <li><a href="{{ user.url }}">{{ user.username }}</a></li> {% endfor %} </ul>

只有一个在声明{% for user in users %}大括号，而你的语句使用两个花括号：{{% for test in my_list %}}。

试试看：{% for test in my_list %}看看会发生什么。

来源

2017-07-18 09:06:52

就是这样，圣锐我花了这么多时间盲目。有趣的是，额外的大括号可能会导致错误，任何想法为什么可能是这种情况，就解释器生命周期而言？ – Skyler

@Skyler我认为必须深入研究jinja2来源，找出原因。我同意它应该更优雅地失败。 –

Jinja 2对于循环崩溃谷歌应用引擎

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