Question

我的Jinja2模板应该从我的索引页面自动化HTML结构。运行和浏览程序时，浏览器上没有显示任何内容。当我使用一个变量时DID工作，但是当我嵌套几个时出现问题。这是代码：

class MainPage(Handler):
    def get(self):
        stage = [name, lessons]
        name = 'Stage 1'
        lessons = [
                    ['Lesson 1 Important Concepts',[
                        ['HTML', 'HTML is the ...'],
                        ['Tags and Elements', 'This is an e...'],
                        ['Why Computers Are Stupid', 'Computers ne...'],
                        ['Inline and Block Elements', 'Block elem...']
                    ]
                ]
                    ['Lesson 2: Creating a Structured Document with HTML',[
                        ['Developer Tools','Everything design...'],
                        ['HTML is Structured Like a Family Tree','HTML..'],
                        ['Text Editors','HTML is writt....'],
                    ]
                ]
                    ['Lesson 3: Adding Style to HTML Using CSS',[
                        ['Avoiding Repetition','If programm...'],
                        ['CSS','CSS, or cascading style sh....'],
                    ]
                ]   
                    ]   
        self.render("index.html", name=name, lessons=lessons)

以下是模板：

<h1> {{name}} Important Concepts</h1>
{% for lessons in stage %}
<div class=“lesson”>
    <h2>{{ lessons[0] }}</h2>
    <div class="concept”>
        <div class="concept-title">
            {{ lessons[0][0] }}
        </div>
        <div class="concept-description">
            {{ lessons[0][1] }}
        </div>
    </div>
</div>
{% endfor %}

我的GitHub项目在这里：https://github.com/graceehayden/Stage4Udacity-Session-2

我得到的错误是：

Traceback (most recent call last):
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1535, in __call__
    rv = self.handle_exception(request, response, e)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1529, in __call__
    rv = self.router.dispatch(request, response)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.2/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/Users/gracehayden/Desktop/Udacity/Stage4Project/main.py", line 22, in get
    stage = [name, lessons]
UnboundLocalError: local variable 'name' referenced before assignment

Answer 1

值只能在之后使用。因此，而不是：

stage = [name, lessons] # this fails because "name" and "lessons" aren't yet set
name = 'Stage 1'
lessons = [] # big value here

重新排序这些行，将name和lessons（定义其值）的定义放在这些值用于定义stage的位置之前：

name = 'Stage 1'
lessons = [] # big value here
stage = [name, lessons]

为什么我的Jinja2模板不起作用？

1 个答案: