(semi fixed?) misleading template error messages. (only some versions)

[castilma]

if you run this server and visit localhost:8080/myroute/foo, you get a template error:

will now serve on port  8080
Traceback (most recent call last):
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/tweens.py", line 12, in _error_handler
    response = request.invoke_exception_view(exc_info)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/view.py", line 756, in invoke_exception_view
    raise HTTPNotFound
pyramid.httpexceptions.HTTPNotFound: The resource could not be found.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.5/wsgiref/handlers.py", line 137, in run
    self.result = application(self.environ, self.start_response)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/router.py", line 270, in __call__
    response = self.execution_policy(environ, self)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/router.py", line 278, in default_execution_policy
    return request.invoke_exception_view(reraise=True)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/view.py", line 755, in invoke_exception_view
    reraise_(*exc_info)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/compat.py", line 148, in reraise
    raise value
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/router.py", line 276, in default_execution_policy
    return router.invoke_request(request)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/router.py", line 249, in invoke_request
    response = handle_request(request)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/tweens.py", line 41, in excview_tween
    response = _error_handler(request, exc)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/tweens.py", line 16, in _error_handler
    reraise(*exc_info)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/compat.py", line 148, in reraise
    raise value
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/tweens.py", line 39, in excview_tween
    response = handler(request)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/router.py", line 156, in handle_request
    view_name
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/view.py", line 642, in _call_view
    response = view_callable(context, request)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/viewderivers.py", line 462, in rendered_view
    request, result, view_inst, context)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/renderers.py", line 435, in render_view
    return self.render_to_response(response, system, request=request)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/renderers.py", line 458, in render_to_response
    result = self.render(value, system_values, request=request)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid/renderers.py", line 454, in render
    result = renderer(value, system_values)
  File "/home/pi/.local/lib/python3.5/site-packages/pyramid_chameleon/zpt.py", line 47, in __call__
    result = self.template(**system)
  File "/home/pi/.local/lib/python3.5/site-packages/chameleon/template.py", line 124, in __call__
    return self.render(**kwargs)
  File "/home/pi/.local/lib/python3.5/site-packages/chameleon/zpt/template.py", line 297, in render
    return super(PageTemplate, self).render(**_kw)
  File "/home/pi/.local/lib/python3.5/site-packages/chameleon/template.py", line 191, in render
    raise_with_traceback(exc, tb)
  File "/home/pi/.local/lib/python3.5/site-packages/chameleon/utils.py", line 75, in raise_with_traceback
    raise exc
  File "/home/pi/.local/lib/python3.5/site-packages/chameleon/template.py", line 171, in render
    self._render(stream, econtext, rcontext)
  File "index_161d98e17b5a3f24d86304929b34b0af.py", line 200, in render
  File "/home/pi/.local/lib/python3.5/site-packages/chameleon/zpt/template.py", line 301, in include
    self._render(*args, **kwargs)
  File "base_9068126ef4690e8b4198d76bc88e1dfb.py", line 305, in render
  File "index_161d98e17b5a3f24d86304929b34b0af.py", line 136, in __fill_content
  File "/home/pi/.local/lib/python3.5/site-packages/chameleon/utils.py", line 406, in __getitem__
    raise NameError(key)
NameError: undecl_name

 - Expression: "pair[0]"
 - Filename:   /home/pi/code/pathbug/project/templates/base.pt
 - Location:   (line 14: col 75)
 - Source:     ... oute/${pair[1]}" tal:content="pair[0]" /></li>
                                                 ^^^^^^^
 - Expression: "load: base.pt"
 - Filename:   /home/pi/code/pathbug/project/templates/index.pt
 - Location:   (line 1: col 23)
 - Source:     <metal:main use-macro="load: base.pt">
                                      ^^^^^^^^^^^^^
 - Arguments:  get_csrf_token: <partial - at 0x75deab70>
               content: some spec content
               request: <Request - at 0x75dd4b90>
               repeat: {...} (0)
               current_spec: sec
               view: <function art_desc at 0x75dd38e8>
               target_language: <NoneType - at 0x3e5788>
               macroname: load: base.pt
               context: <DefaultRootFactory None at 0x75dd4bb0>
               renderer_name: templates/index.pt
               renderer_info: <RendererHelper - at 0x75dd4e50>
               req: <Request - at 0x75dd4b90>
               tuples: <list - at 0x75e47328>
192.168.178.5 - - [16/Feb/2018 00:07:10] "GET /myroute/sec HTTP/1.1" 500 59

the problem is the 'undecl_name' in the file templates/index.pt. The NameError mentions that, but the following info is misleading. It looks like the error is in base.pt in the expression pair[0]. but that is not the case!

I have to say, that I get this misleading error message only on a raspberry pi. here is the output of pip show:

Chameleon (3.2)
cryptography (1.7.1)
Cython (0.26)
hupper (1.0)
idna (2.2)
keyring (10.1)
keyrings.alt (1.3)
numpy (1.12.1)
PasteDeploy (1.5.2)
Pillow (4.0.0)
pip (9.0.1)
plaster (1.0)
plaster-pastedeploy (0.4.2)
pyasn1 (0.1.9)
pycrypto (2.6.1)
Pygments (2.2.0)
pygobject (3.22.0)
pyramid (1.9.1)
pyramid-chameleon (0.3)
python-apt (1.1.0b5)
pyxdg (0.25)
repoze.lru (0.7)
SecretStorage (2.3.1)
setuptools (38.5.1)
six (1.10.0)
translationstring (1.3)
unattended-upgrades (0.1)
venusian (1.1.0)
waitress (1.1.0)
WebOb (1.8.0rc1)
wheel (0.29.0)
zope.deprecation (4.3.0)
zope.interface (4.4.3)

on nixos with nix-shell -p python36Packages.pyramid -p python36Packages.cookiecutter -p python36Packages.waitress -p python36Packages.pyramid_chameleon, the error message is not misleading:

Traceback (most recent call last):
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/tweens.py", line 12, in _error_handler
    response = request.invoke_exception_view(exc_info)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/view.py", line 756, in invoke_exception_view
    raise HTTPNotFound
pyramid.httpexceptions.HTTPNotFound: The resource could not be found.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/nix/store/z1avajv6hrjcx9nb07x9nd6cklb45w2r-python3-3.6.4/lib/python3.6/wsgiref/handlers.py", line 137, in run
    self.result = application(self.environ, self.start_response)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/router.py", line 270, in __call__
    response = self.execution_policy(environ, self)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/router.py", line 278, in default_execution_policy
    return request.invoke_exception_view(reraise=True)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/view.py", line 755, in invoke_exception_view
    reraise_(*exc_info)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/compat.py", line 148, in reraise
    raise value
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/router.py", line 276, in default_execution_policy
    return router.invoke_request(request)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/router.py", line 249, in invoke_request
    response = handle_request(request)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/tweens.py", line 41, in excview_tween
    response = _error_handler(request, exc)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/tweens.py", line 16, in _error_handler
    reraise(*exc_info)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/compat.py", line 148, in reraise
    raise value
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/tweens.py", line 39, in excview_tween
    response = handler(request)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/router.py", line 156, in handle_request
    view_name
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/view.py", line 642, in _call_view
    response = view_callable(context, request)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/viewderivers.py", line 462, in rendered_view
    request, result, view_inst, context)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/renderers.py", line 435, in render_view
    return self.render_to_response(response, system, request=request)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/renderers.py", line 458, in render_to_response
    result = self.render(value, system_values, request=request)
  File "/nix/store/gda1y88nj01wm23mr5ymwdygwbkcg20q-python3.6-pyramid-1.9.1/lib/python3.6/site-packages/pyramid/renderers.py", line 454, in render
    result = renderer(value, system_values)
  File "/nix/store/bp5ckki3qmn908kzi10v9hy7qvmldc79-python3.6-pyramid_chameleon-0.3/lib/python3.6/site-packages/pyramid_chameleon/zpt.py", line 47, in __call__
    result = self.template(**system)
  File "/nix/store/jl484syhb8yzgkxdblg2i7dfli33bkig-python3.6-Chameleon-2.25/lib/python3.6/site-packages/chameleon/template.py", line 124, in __call__
    return self.render(**kwargs)
  File "/nix/store/jl484syhb8yzgkxdblg2i7dfli33bkig-python3.6-Chameleon-2.25/lib/python3.6/site-packages/chameleon/zpt/template.py", line 261, in render
    return super(PageTemplate, self).render(**vars)
  File "/nix/store/jl484syhb8yzgkxdblg2i7dfli33bkig-python3.6-Chameleon-2.25/lib/python3.6/site-packages/chameleon/template.py", line 191, in render
    raise_with_traceback(exc, tb)
  File "/nix/store/jl484syhb8yzgkxdblg2i7dfli33bkig-python3.6-Chameleon-2.25/lib/python3.6/site-packages/chameleon/utils.py", line 75, in raise_with_traceback
    raise exc
  File "/nix/store/jl484syhb8yzgkxdblg2i7dfli33bkig-python3.6-Chameleon-2.25/lib/python3.6/site-packages/chameleon/template.py", line 171, in render
    self._render(stream, econtext, rcontext)
  File "index_3612173be5b84f0f49f78e49664f6700.py", line 187, in render
  File "/nix/store/jl484syhb8yzgkxdblg2i7dfli33bkig-python3.6-Chameleon-2.25/lib/python3.6/site-packages/chameleon/zpt/template.py", line 265, in include
    self._render(*args, **kwargs)
  File "base_4b530c1718bcb6334b096e47679d39d6.py", line 300, in render
  File "index_3612173be5b84f0f49f78e49664f6700.py", line 130, in __fill_content
  File "/nix/store/jl484syhb8yzgkxdblg2i7dfli33bkig-python3.6-Chameleon-2.25/lib/python3.6/site-packages/chameleon/utils.py", line 406, in __getitem__
    raise NameError(key)
NameError: undecl_name

 - Expression: "undecl_name"
 - Filename:   /home/mcd/tmp/project/rep/project/templates/index.pt
 - Location:   (line 6: col 58)
 - Source:     ... pec | nothing" tal:content="undecl_name" />
                                               ^^^^^^^^^^^
 - Arguments:  view: <function art_desc at 0x7f4ab51a5a60>
               renderer_name: templates/index.pt
               renderer_info: <RendererHelper - at 0x7f4ab50d2320>
               context: <DefaultRootFactory None at 0x7f4ab5197ba8>
               request: <Request - at 0x7f4ab5189d68>
               req: <Request - at 0x7f4ab5189d68>
               get_csrf_token: <partial - at 0x7f4ab5174138>
               content: some spec content
               tuples: <list - at 0x7f4ab5192a88>
               current_spec: sec
               repeat: {...} (0)
127.0.0.1 - - [16/Feb/2018 13:14:13] "GET /myroute/sec HTTP/1.1" 500 59

I report this, because the versions seem to be the same (look here): pyramid 1.9.1 and pyramid_chameleon 0.3. So I'm not sure if you fixed the error reporting, or if it broke recently.

[malthe]

There is some problem currently with error messages – I have seen the same. I'm going to try and find time to look at it in detail.

Should be an easy fix, once identified.

[malthe]

Does this pull request fix your issue:

#261 – ?

[castilma]

no.