将列表参数传递给Jinja2扩展中的调用节点

我一直在努力创建Jinja2几个小时的扩展，并且似乎我肯定停留在一个特定的点上：将列表参数传递给调用节点。我尝试从其他一些工作扩展中获得灵感，并且我无法明白为什么我的内容在我的参考代码不起作用时无法工作。将列表参数传递给Jinja2扩展中的调用节点

基本上我想要的是有这种东西在我的模板：

{% usebundle "common", "treeview" %}

这应该在上下文中的“共同”和“树形”字符串添加到列表中的一些。

这里是我的代码的关键部分：

class MyExtension(Extension): 
    def __init__(self, environment): 
    super(MyExtension, self).__init__(environment) 

    def parse(self, parser): 
    lineno = parser.stream.next().lineno 
    names = [] 
    while parser.stream.current.type != 'block_end': 
     names.append(parser.parse_expression()) 
     parser.stream.skip_if('comma') 

    # At this point, names is a correctly filled array of names 
    call = self.call_method('_callback', args=[nodes.List(names)]) 
    result = nodes.CallBlock([call], [], [], []) 
    result.set_lineno(lineno) 
    return result 

    def _callback(self, names, caller=None): 
    # Here names should contain a list of names, but it's either undefined or 
    # a list of Undefined, or I get an error before reaching this callback 
    # (generally saying that arguments cannot be read) 
    pass

我试过几件事情，但让我说，真正的问题是在参数格式（我names价值的内容的东西解析函数）是，如果我用nodes.Const(42)替换nodes.List(names)，我会在回调参数中收到正确的42值。

[编辑]这个版本的代码错误详细信息如下：

Exception on /login [GET] 
Traceback (most recent call last): 
    File "E:\Python27\lib\site-packages\flask-0.9-py2.7.egg\flask\app.py", line 1687, in wsgi_app 
    response = self.full_dispatch_request() 
    File "E:\Python27\lib\site-packages\flask-0.9-py2.7.egg\flask\app.py", line 1360, in full_dispatch_request 
    rv = self.handle_user_exception(e) 
    File "E:\Python27\lib\site-packages\flask-0.9-py2.7.egg\flask\app.py", line 1358, in full_dispatch_request 
    rv = self.dispatch_request() 
    File "E:\Python27\lib\site-packages\flask-0.9-py2.7.egg\flask\app.py", line 1344, in dispatch_request 
    return self.view_functions[rule.endpoint](**req.view_args) 
    File "E:\myapplication\user.py", line 126, in login 
    return template_or_json('user/login.html', form=form) 
    File "E:\myapplication\ajax.py", line 32, in template_or_json 
    return render_template(template_name, **context) 
    File "E:\Python27\lib\site-packages\flask-0.9-py2.7.egg\flask\templating.py", line 125, in render_template 
    context, ctx.app) 
    File "E:\Python27\lib\site-packages\flask-0.9-py2.7.egg\flask\templating.py", line 107, in _render 
    rv = template.render(context) 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\environment.py", line 894, in render 
    return self.environment.handle_exception(exc_info, True) 
    File "E:\myapplication\templates\user\login.html", line 1, in top-level template code 
    {% extends "layout.html" %} 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\environment.py", line 443, in _generate 
    return generate(source, self, name, filename, defer_init=defer_init) 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\compiler.py", line 63, in generate 
    generator.visit(node) 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\visitor.py", line 38, in visit 
    return f(node, *args, **kwargs) 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\compiler.py", line 803, in visit_Template 
    frame.inspect(node.body) 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\compiler.py", line 201, in inspect 
    visitor.visit(node) 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\visitor.py", line 38, in visit 
    return f(node, *args, **kwargs) 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\compiler.py", line 347, in visit_CallBlock 
    self.visit(node.call) 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\visitor.py", line 39, in visit 
    return self.generic_visit(node, *args, **kwargs) 
    File "E:\Python27\lib\site-packages\jinja2-2.6-py2.7.egg\jinja2\visitor.py", line 43, in generic_visit 
    for node in node.iter_child_nodes(): 
AttributeError: 'list' object has no attribute 'iter_child_nodes'

来源

2012-08-16 Shtong

为了得到你要包括你的错误信息和/或完整回溯更好的答案。 – stderr 2012-08-16 13:29:39

CallBlock预计实际调用作为第一个参数，而不是一些话费清单。

所以，你只需要使用的

nodes.CallBlock(call, [], [], [])

代替

nodes.CallBlock([call], [], [], [])

来源

2013-03-05 10:55:23 jcdenton

将列表参数传递给Jinja2扩展中的调用节点

回答

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