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Better error message when view return type is not supported

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Before, returning a `bool` from a route caused the error

```
[2019-05-31 10:08:42,216] ERROR in app: Exception on / [GET]
Traceback (most recent call last):
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 2070, in make_response
    rv = self.response_class.force_type(rv, request.environ)
  File "/Users/johnzeringue/Documents/ts-open/flask/env/lib/python3.7/site-packages/werkzeug/wrappers/base_response.py", line 269, in force_type
    response = BaseResponse(*_run_wsgi_app(response, environ))
  File "/Users/johnzeringue/Documents/ts-open/flask/env/lib/python3.7/site-packages/werkzeug/wrappers/base_response.py", line 26, in _run_wsgi_app
    return _run_wsgi_app(*args)
  File "/Users/johnzeringue/Documents/ts-open/flask/env/lib/python3.7/site-packages/werkzeug/test.py", line 1119, in run_wsgi_app
    app_rv = app(environ, start_response)
TypeError: 'bool' object is not callable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 2393, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 1906, in full_dispatch_request
    return self.finalize_request(rv)
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 1921, in finalize_request
    response = self.make_response(rv)
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 2078, in make_response
    reraise(TypeError, new_error, sys.exc_info()[2])
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/_compat.py", line 39, in reraise
    raise value.with_traceback(tb)
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 2070, in make_response
    rv = self.response_class.force_type(rv, request.environ)
  File "/Users/johnzeringue/Documents/ts-open/flask/env/lib/python3.7/site-packages/werkzeug/wrappers/base_response.py", line 269, in force_type
    response = BaseResponse(*_run_wsgi_app(response, environ))
  File "/Users/johnzeringue/Documents/ts-open/flask/env/lib/python3.7/site-packages/werkzeug/wrappers/base_response.py", line 26, in _run_wsgi_app
    return _run_wsgi_app(*args)
  File "/Users/johnzeringue/Documents/ts-open/flask/env/lib/python3.7/site-packages/werkzeug/test.py", line 1119, in run_wsgi_app
    app_rv = app(environ, start_response)
TypeError: 'bool' object is not callable
The view function did not return a valid response. The return type must be a string, tuple, Response instance, or WSGI callable, but it was a bool.
```

Now, it returns the more readable

```
[2019-05-31 10:36:19,500] ERROR in app: Exception on / [GET]
Traceback (most recent call last):
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 2400, in wsgi_app
    response = self.full_dispatch_request()
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 1907, in full_dispatch_request
    return self.finalize_request(rv)
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 1922, in finalize_request
    response = self.make_response(rv)
  File "/Users/johnzeringue/Documents/ts-open/flask/flask/app.py", line 2085, in make_response
    " {rv.__class__.__name__}.".format(rv=rv))
TypeError: The view function did not return a valid response. The return type must be a string, dict, tuple, Response instance, or WSGI callable, but it was a bool.
```

Fixes #3214
This commit is contained in:
John Zeringue 2019-05-31 10:56:01 -04:00
parent 6ac4b93779
commit 8bb7185284
3 changed files with 19 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

2
CHANGES.rst
View file

@ -64,6 +64,8 @@ Unreleased
- When using the test client as a context manager (``with client:``),
all preserved request contexts are popped when the block exits,
ensuring nested contexts are cleaned up correctly. :pr:`3157`
- Show a better error message when the view return type is not
supported. :issue:`3214`
.. _#2935: https://github.com/pallets/flask/issues/2935
.. _#2957: https://github.com/pallets/flask/issues/2957

12
flask/app.py
View file

@ -27,6 +27,7 @@ from werkzeug.exceptions import (
default_exceptions,
)
from werkzeug.routing import BuildError, Map, RequestRedirect, RoutingException, Rule
from werkzeug.wrappers import BaseResponse
from . import cli, json
from ._compat import integer_types, reraise, string_types, text_type
@ -2063,7 +2064,7 @@ class Flask(_PackageBoundObject):
status = headers = None
elif isinstance(rv, dict):
rv = jsonify(rv)
else:
elif isinstance(rv, BaseResponse) or callable(rv):
# evaluate a WSGI callable, or coerce a different response
# class to the correct type
try:
@ -2071,11 +2072,18 @@ class Flask(_PackageBoundObject):
except TypeError as e:
new_error = TypeError(
"{e}\nThe view function did not return a valid"
" response. The return type must be a string, tuple,"
" response. The return type must be a string, dict, tuple,"
" Response instance, or WSGI callable, but it was a"
" {rv.__class__.__name__}.".format(e=e, rv=rv)
)
reraise(TypeError, new_error, sys.exc_info()[2])
else:
raise TypeError(
"The view function did not return a valid"
" response. The return type must be a string, dict, tuple,"
" Response instance, or WSGI callable, but it was a"
" {rv.__class__.__name__}.".format(rv=rv)
)
# prefer the status if it was provided
if status is not None:

10
tests/test_basic.py
View file

@ -1218,17 +1218,21 @@ def test_response_type_errors():
with pytest.raises(TypeError) as e:
c.get("/none")
assert "returned None" in str(e)
assert "returned None" in str(e)
with pytest.raises(TypeError) as e:
c.get("/small_tuple")
assert "tuple must have the form" in str(e)
assert "tuple must have the form" in str(e)
pytest.raises(TypeError, c.get, "/large_tuple")
with pytest.raises(TypeError) as e:
c.get("/bad_type")
assert "it was a bool" in str(e)
assert "object is not callable" not in str(e)
assert "it was a bool" in str(e)
pytest.raises(TypeError, c.get, "/bad_wsgi")