Improve formatting of text tracebacks in technical 500 responses.

[Daniel Hahler]

I think it would do better without extra newlines, and could just match the default output from Python itself.

Currently:

Traceback:

File "…/Vcs/django/django/template/base.py" in __init__
  663.                 token.Meh

During handling of the above exception ('str' object has no attribute 'Meh'), another exception occurred:

File "…/Vcs/django/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "…/Vcs/django/django/core/handlers/base.py" in _get_response
  145.                 response = self.process_exception_by_middleware(e, request)

File "…/Vcs/django/django/core/handlers/base.py" in _get_response
  143.                 response = response.render()

File "…/Vcs/django/django/template/response.py" in render
  106.             self.content = self.rendered_content

File "…/Vcs/django/django/template/response.py" in rendered_content
  83.         content = template.render(context, self._request)

File "…/Vcs/django/django/template/backends/django.py" in render
  61.             return self.template.render(context)

File "…/Vcs/django/django/template/base.py" in render
  171.                     return self._render(context)

File "…/Vcs/django/django/test/utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "…/Vcs/django/django/template/base.py" in render
  940.                 bit = node.render_annotated(context)

File "…/Vcs/django/django/template/base.py" in render_annotated
  907.             return self.render(context)

File "…/Vcs/django/django/template/loader_tags.py" in render
  150.             return compiled_parent._render(context)

File "…/Vcs/django/django/test/utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "…/Vcs/django/django/template/base.py" in render
  940.                 bit = node.render_annotated(context)

File "…/Vcs/django/django/template/base.py" in render_annotated
  907.             return self.render(context)

File "…/Vcs/django/django/template/loader_tags.py" in render
  127.         compiled_parent = self.get_parent(context)

File "…/Vcs/django/django/template/loader_tags.py" in get_parent
  124.         return self.find_template(parent, context)

File "…/Vcs/django/django/template/loader_tags.py" in find_template
  104.             template_name, skip=history,

File "…/Vcs/django/django/template/engine.py" in find_template
  125.                 template = loader.get_template(name, skip=skip)

File "…/Vcs/django/django/template/loaders/base.py" in get_template
  30.                     contents, origin, origin.template_name, self.engine,

File "…/Vcs/django/django/template/base.py" in __init__
  156.         self.nodelist = self.compile_nodelist()

File "…/Vcs/django/django/template/base.py" in compile_nodelist
  194.             return parser.parse()

File "…/Vcs/django/django/template/base.py" in parse
  449.                     raise self.error(token, e)

File "…/Vcs/django/django/template/base.py" in parse
  447.                     filter_expression = self.compile_filter(token.contents)

File "…/Vcs/django/django/template/base.py" in compile_filter
  563.         return FilterExpression(token, self)

File "…/Vcs/django/django/template/base.py" in __init__
  666.                                           "from '%s'" % (token[upto:], token))

Exception Type: TemplateSyntaxError at /a/login
Exception Value: Could not parse the remainder: '("foo")' from 'myecho("foo")'

Better:

Traceback (most recent call last):
  File "…/Vcs/django/django/template/base.py", line 663, in __init__
    token.Meh

During handling of the above exception ('str' object has no attribute 'Meh'), another exception occurred:
  File "…/Vcs/django/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "…/Vcs/django/django/core/handlers/base.py", line 145, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "…/Vcs/django/django/core/handlers/base.py", line 143, in _get_response
    response = response.render()
  File "…/Vcs/django/django/template/response.py", line 106, in render
    self.content = self.rendered_content
  File "…/Vcs/django/django/template/response.py", line 83, in rendered_content
    content = template.render(context, self._request)
  File "…/Vcs/django/django/template/backends/django.py", line 61, in render
    return self.template.render(context)
  File "…/Vcs/django/django/template/base.py", line 171, in render
    return self._render(context)
  File "…/Vcs/django/django/test/utils.py", line 96, in instrumented_test_render
    return self.nodelist.render(context)
  File "…/Vcs/django/django/template/base.py", line 940, in render
    bit = node.render_annotated(context)
  File "…/Vcs/django/django/template/base.py", line 907, in render_annotated
    return self.render(context)
  File "…/Vcs/django/django/template/loader_tags.py", line 150, in render
    return compiled_parent._render(context)
  File "…/Vcs/django/django/test/utils.py", line 96, in instrumented_test_render
    return self.nodelist.render(context)
  File "…/Vcs/django/django/template/base.py", line 940, in render
    bit = node.render_annotated(context)
  File "…/Vcs/django/django/template/base.py", line 907, in render_annotated
    return self.render(context)
  File "…/Vcs/django/django/template/loader_tags.py", line 127, in render
    compiled_parent = self.get_parent(context)
  File "…/Vcs/django/django/template/loader_tags.py", line 124, in get_parent
    return self.find_template(parent, context)
  File "…/Vcs/django/django/template/loader_tags.py", line 104, in find_template
    template_name, skip=history,
  File "…/Vcs/django/django/template/engine.py", line 125, in find_template
    template = loader.get_template(name, skip=skip)
  File "…/Vcs/django/django/template/loaders/base.py", line 30, in get_template
    contents, origin, origin.template_name, self.engine,
  File "…/Vcs/django/django/template/base.py", line 156, in __init__
    self.nodelist = self.compile_nodelist()
  File "…/Vcs/django/django/template/base.py", line 194, in compile_nodelist
    return parser.parse()
  File "…/Vcs/django/django/template/base.py", line 449, in parse
    raise self.error(token, e)
  File "…/Vcs/django/django/template/base.py", line 447, in parse
    filter_expression = self.compile_filter(token.contents)
  File "…/Vcs/django/django/template/base.py", line 563, in compile_filter
    return FilterExpression(token, self)
  File "…/Vcs/django/django/template/base.py", line 666, in __init__
    "from '%s'" % (token[upto:], token))

Exception Type: TemplateSyntaxError at /a/login
Exception Value: Could not parse the remainder: '("foo")' from 'myecho("foo")'

[Daniel Hahler]

There are two other issues here:

1. I would like to have it more at the bottom
2. the "Template error" part is not plain text:

   Template error:
   In template …/templates/base.html, error at line 10
      Could not parse the remainder: '("foo")' from 'myecho("foo")'
      1 : {# {% extends "base.html" %} #}
      2 :
      …
      12 : </html>
      13 :
   

[Carlton Gibson]

OK, fine, improvements here welcome. Marking Easy Pickings... since it should just be formatting/template changes.

[Daniel Hahler]

@Naved
Just to make sure it's not missed, there is an initial PR already at ​https://github.com/django/django/pull/11287.

[Mariusz Felisiak]

​PR

[Carlton Gibson]

Deassigning due to inactivity. (PR should be a good starting point.)

[孙译喆]

I'm new to Django and I am intending to accept this issue. However I have a few questions to ask.
Firstly, how to make Django use technical_500.txt as a template? When I raise exceptions in views Django use technical_500.html instead.
Secondly, why is the existing pull request not accepted, and how can I improve it?

[Jerrod Martin]

New pull request with tests. ​https://github.com/django/django/pull/11596

[Mariusz Felisiak <felisiak.mariusz@…>]

In c7bef16:

Fixed #30411 -- Improved formatting of text tracebacks in technical 500 templates.

Co-Authored-By: Daniel Hahler <git@…>