Compiled templates with macros do not work on app engine

问题

I use Jinja2 compiled templates and a module loader to load the compiled templates (python code) from the datastore. But when my template contains a macro it does not work on app engine: TypeError: 'NoneType' object is not callable

But in the app engine SDK it works fine. And when I skip the macro call, i receive the same error.

Without the macro it works fine. Without a solution for this macro problem, I call a python function in my template to implement the functionality of the macro.

Update: This is the template source code which results in an error:

{% extends "mainpage.html" %}
{% block form %}
    {% macro test_macro(name) %}
        <p>{{ name }}</p>
    {% endmacro %}
    <div>
    {{ test_macro('John Doe') }}
    </div>
{% endblock %}

And this is the compiled template code (the form block part):

def block_form(context, environment=environment):
    if 0: yield None
    yield u'\n'
    def macro(l_name):
        t_1 = []
        pass
        t_1.extend((
            u'\n<p>', 
            to_string(l_name), 
            u'</p>\n', 
        ))
        return concat(t_1)
    l_test_macro = Macro(environment, macro, 'test_macro', ('name',), (), False, False, False)
    yield u'\n<div>\n\t%s\n</div>\n' % (
        context.call(l_test_macro, 'John Doe'), 
    )

Update: After some debugging it worked. But I do understand it!!! The problem: I lose my imports. And when I redefine my imports in the code. It worked.

The top of the module:

from __future__ import division
from jinja2.runtime import LoopContext, TemplateReference, Macro, Markup, TemplateRuntimeError, missing, concat, escape, markup_join, unicode_join, to_string, identity, TemplateNotFound
__jinja_template__ = None

To make it work I had to add an inline import:

from jinja2.runtime import Macro     # import again ?????     
l_test_macro = Macro(environment, macro, 'test_macro', ('name',), (), False, False, False)    

Can somebody explain, how I can lose my imports ??? I have this problem only in app engine and NOT in the SDK ??? Is this a namespace problem?

回答1:

I was able to solve it, by adding the module to the sys.modules. But I do not understand why it worked in the SDK and not in GAE when I use a macro

Here is the code of my changed module loader.

def get_module(self, environment, template):
    # Convert the path to a module name
    name = template.replace('.html', '').replace('.txt','').replace('/', '.')   # NO extensions   
    module = None

    if self.package == None :                                           # load from db and not from package
        logging.info('load module : ' + name)                           # load module from runtimes db 
        if name in sys.modules : return sys.modules[name]               # already imported              
        try :
            runtime = models.Runtimes.rtimes_get_by_key_name(template)
            module_code = db.Text(runtime.compiled)                                 
            module = imp.new_module(name)
            exec module_code in module.__dict__                                         
            sys.modules[name] = module                                  # add to sys modules, so no import again
            return module
        except (ImportError, AttributeError):
            logging.error('load failed : ' + name)

    else : .... # load from package

    raise TemplateNotFound(template)

来源：https://stackoverflow.com/questions/13485294/compiled-templates-with-macros-do-not-work-on-app-engine