pyramid.events.BeforeRender: fix the UnicodeDecodeError exception on rendering template

subscriber.py

# encoding:utf-8
u"""

用比较恶心的办法解决模板渲染时出现 UnicodeDecodeError 的问题


This subscriber try to convert all <str> to <unicode>
functional available for Chameleon, Jinja2, and Mako


[2014-04-23] work with:

    chameleon==2.14
    pyramid_chameleon==0.1
    
    jinja2==2.7.2
    pyramid_jinja2==1.10
    
    mako==0.9.1
    pyramid_mako==0.3.1

"""

from pyramid.interfaces import IRendererFactory
    
def tmpl_unicode(event):
    ''' event ~ pyramid.events.BeforeRender

    fix the UnicodeDecodeError

    :  renderer.template.encoding ~ chameleon.PageTemplate.render
    :  renderer.environment ~ jinja2.environment.Environment.finalize
    :  renderer.lookup ~ mako.lookup.TemplateLookup.template_args
    '''

    info = event['renderer_info']

    renderer_factory = info.registry.getUtilitiesFor(IRendererFactory)
    factory = dict(renderer_factory)

    # if info.type == '.pt':
    if factory[info.type] == factory['.pt']:
        info.renderer.template.encoding = 'utf-8'

    elif factory[info.type] == factory['.jinja2']:
        env = info.renderer.environment
        env.finalize = lambda x: \
            unicode(x,'utf-8') if isinstance(x, str) else x

    elif factory[info.type] == factory['.mako']:
        args = info.renderer.lookup.template_args
        filters = args['default_filters']
        if 'decode.utf8' not in filters:  # not 'decode.utf-8'
            filters.insert(0, 'decode.utf8') # append will fail
        # args['output_encoding'] = 'utf-8'
        # args['encoding_errors'] = 'replace'
        

def includeme(config):
    config.add_subscriber(tmpl_unicode, 'pyramid.events.BeforeRender')