Changes

Version 3.0.2

Released 2024-02-03

  • Correct type for jinja_loader property. #5388
  • Fix error with --extra-files and --exclude-patterns CLI options. #5391

Version 3.0.1

Released 2024-01-18

  • Correct type for path argument to send_file. #5230
  • Fix a typo in an error message for the flask run --key option. #5344
  • Session data is untagged without relying on the built-in json.loads object_hook. This allows other JSON providers that don’t implement that. #5381
  • Address more type findings when using mypy strict mode. #5383

Version 3.0.0

Released 2023-09-30

  • Remove previously deprecated code. #5223
  • Deprecate the __version__ attribute. Use feature detection, or importlib.metadata.version("flask"), instead. #5230
  • Restructure the code such that the Flask (app) and Blueprint classes have Sans-IO bases. #5127
  • Allow self as an argument to url_for. #5264
  • Require Werkzeug >= 3.0.0.

Version 2.3.3

Released 2023-08-21

  • Python 3.12 compatibility.
  • Require Werkzeug >= 2.3.7.
  • Use flit_core instead of setuptools as build backend.
  • Refactor how an app’s root and instance paths are determined. #5160

Version 2.3.2

Released 2023-05-01

  • Set Vary: Cookie header when the session is accessed, modified, or refreshed.
  • Update Werkzeug requirement to >=2.3.3 to apply recent bug fixes.

Version 2.3.1

Released 2023-04-25

  • Restore deprecated from flask import Markup. #5084

Version 2.3.0

Released 2023-04-25

  • Drop support for Python 3.7. #5072
  • Update minimum requirements to the latest versions: Werkzeug>=2.3.0, Jinja2>3.1.2, itsdangerous>=2.1.2, click>=8.1.3.

  • Remove previously deprecated code. #4995

  • The push and pop methods of the deprecated _app_ctx_stack and _request_ctx_stack objects are removed. top still exists to give extensions more time to update, but it will be removed.

  • The FLASK_ENV environment variable, ENV config key, and app.env property are removed.
  • The session_cookie_name, send_file_max_age_default, use_x_sendfile, propagate_exceptions, and templates_auto_reload properties on app are removed.
  • The JSON_AS_ASCII, JSON_SORT_KEYS, JSONIFY_MIMETYPE, and JSONIFY_PRETTYPRINT_REGULAR config keys are removed.
  • The app.before_first_request and bp.before_app_first_request decorators are removed.
  • json_encoder and json_decoder attributes on app and blueprint, and the corresponding json.JSONEncoder and JSONDecoder classes, are removed.
  • The json.htmlsafe_dumps and htmlsafe_dump functions are removed.
  • Calling setup methods on blueprints after registration is an error instead of a warning. #4997
  • Importing escape and Markup from flask is deprecated. Import them directly from markupsafe instead. #4996
  • The app.got_first_request property is deprecated. #4997
  • The locked_cached_property decorator is deprecated. Use a lock inside the decorated function if locking is needed. #4993
  • Signals are always available. blinker>=1.6.2 is a required dependency. The signals_available attribute is deprecated. #5056
  • Signals support async subscriber functions. #5049
  • Remove uses of locks that could cause requests to block each other very briefly. #4993
  • Use modern packaging metadata with pyproject.toml instead of setup.cfg. #4947
  • Ensure subdomains are applied with nested blueprints. #4834
  • config.from_file can use text=False to indicate that the parser wants a binary file instead. #4989
  • If a blueprint is created with an empty name it raises a ValueError. #5010
  • SESSION_COOKIE_DOMAIN does not fall back to SERVER_NAME. The default is not to set the domain, which modern browsers interpret as an exact match rather than a subdomain match. Warnings about localhost and IP addresses are also removed. #5051
  • The routes command shows each rule’s subdomain or host when domain matching is in use. #5004
  • Use postponed evaluation of annotations. #5071

Version 2.2.5

Released 2023-05-02

  • Update for compatibility with Werkzeug 2.3.3.
  • Set Vary: Cookie header when the session is accessed, modified, or refreshed.

Version 2.2.4

Released 2023-04-25

  • Update for compatibility with Werkzeug 2.3.

Version 2.2.3

Released 2023-02-15

  • Autoescape is enabled by default for .svg template files. #4831
  • Fix the type of template_folder to accept pathlib.Path. #4892
  • Add --debug option to the flask run command. #4777

Version 2.2.2

Released 2022-08-08

  • Update Werkzeug dependency to >= 2.2.2. This includes fixes related to the new faster router, header parsing, and the development server. #4754
  • Fix the default value for app.env to be "production". This attribute remains deprecated. #4740

Version 2.2.1

Released 2022-08-03

  • Setting or accessing json_encoder or json_decoder raises a deprecation warning. #4732

Version 2.2.0

Released 2022-08-01

  • Remove previously deprecated code. #4667

  • Old names for some send_file parameters have been removed. download_name replaces attachment_filename, max_age replaces cache_timeout, and etag replaces add_etags. Additionally, path replaces filename in send_from_directory.

  • The RequestContext.g property returning AppContext.g is removed.
  • Update Werkzeug dependency to >= 2.2.

  • The app and request contexts are managed using Python context vars directly rather than Werkzeug’s LocalStack. This should result in better performance and memory use. #4682

  • Extension maintainers, be aware that _app_ctx_stack.top and _request_ctx_stack.top are deprecated. Store data on g instead using a unique prefix, like g._extension_name_attr.

  • The FLASK_ENV environment variable and app.env attribute are deprecated, removing the distinction between development and debug mode. Debug mode should be controlled directly using the --debug option or app.run(debug=True). #4714
  • Some attributes that proxied config keys on app are deprecated: session_cookie_name, send_file_max_age_default, use_x_sendfile, propagate_exceptions, and templates_auto_reload. Use the relevant config keys instead. #4716

  • Add new customization points to the Flask app object for many previously global behaviors.

  • flask.url_for will call app.url_for. #4568

  • flask.abort will call app.aborter. Flask.aborter_class and Flask.make_aborter can be used to customize this aborter. #4567
  • flask.redirect will call app.redirect. #4569
  • flask.json is an instance of JSONProvider. A different provider can be set to use a different JSON library. flask.jsonify will call app.json.response, other functions in flask.json will call corresponding functions in app.json. #4692
  • JSON configuration is moved to attributes on the default app.json provider. JSON_AS_ASCII, JSON_SORT_KEYS, JSONIFY_MIMETYPE, and JSONIFY_PRETTYPRINT_REGULAR are deprecated. #4692
  • Setting custom json_encoder and json_decoder classes on the app or a blueprint, and the corresponding json.JSONEncoder and JSONDecoder classes, are deprecated. JSON behavior can now be overridden using the app.json provider interface. #4692
  • json.htmlsafe_dumps and json.htmlsafe_dump are deprecated, the function is built-in to Jinja now. #4692
  • Refactor register_error_handler to consolidate error checking. Rewrite some error messages to be more consistent. #4559
  • Use Blueprint decorators and functions intended for setup after registering the blueprint will show a warning. In the next version, this will become an error just like the application setup methods. #4571
  • before_first_request is deprecated. Run setup code when creating the application instead. #4605
  • Added the View.init_every_request class attribute. If a view subclass sets this to False, the view will not create a new instance on every request. #2520.
  • A flask.cli.FlaskGroup Click group can be nested as a sub-command in a custom CLI. #3263
  • Add --app and --debug options to the flask CLI, instead of requiring that they are set through environment variables. #2836
  • Add --env-file option to the flask CLI. This allows specifying a dotenv file to load in addition to .env and .flaskenv. #3108
  • It is no longer required to decorate custom CLI commands on app.cli or blueprint.cli with @with_appcontext, an app context will already be active at that point. #2410
  • SessionInterface.get_expiration_time uses a timezone-aware value. #4645
  • View functions can return generators directly instead of wrapping them in a Response. #4629
  • Add stream_template and stream_template_string functions to render a template as a stream of pieces. #4629

  • A new implementation of context preservation during debugging and testing. #4666

  • request, g, and other context-locals point to the correct data when running code in the interactive debugger console. #2836

  • Teardown functions are always run at the end of the request, even if the context is preserved. They are also run after the preserved context is popped.
  • stream_with_context preserves context separately from a with client block. It will be cleaned up when response.get_data() or response.close() is called.
  • Allow returning a list from a view function, to convert it to a JSON response like a dict is. #4672
  • When type checking, allow TypedDict to be returned from view functions. #4695
  • Remove the --eager-loading/--lazy-loading options from the flask run command. The app is always eager loaded the first time, then lazily loaded in the reloader. The reloader always prints errors immediately but continues serving. Remove the internal DispatchingApp middleware used by the previous implementation. #4715

Version 2.1.3

Released 2022-07-13

  • Inline some optional imports that are only used for certain CLI commands. #4606
  • Relax type annotation for after_request functions. #4600
  • instance_path for namespace packages uses the path closest to the imported submodule. #4610
  • Clearer error message when render_template and render_template_string are used outside an application context. #4693

Version 2.1.2

Released 2022-04-28

  • Fix type annotation for json.loads, it accepts str or bytes. #4519
  • The --cert and --key options on flask run can be given in either order. #4459

Version 2.1.1

Released on 2022-03-30

  • Set the minimum required version of importlib_metadata to 3.6.0, which is required on Python < 3.10. #4502

Version 2.1.0

Released 2022-03-28

  • Drop support for Python 3.6. #4335
  • Update Click dependency to >= 8.0. #4008

  • Remove previously deprecated code. #4337

  • The CLI does not pass script_info to app factory functions.

  • config.from_json is replaced by config.from_file(name, load=json.load).
  • json functions no longer take an encoding parameter.
  • safe_join is removed, use werkzeug.utils.safe_join instead.
  • total_seconds is removed, use timedelta.total_seconds instead.
  • The same blueprint cannot be registered with the same name. Use name= when registering to specify a unique name.
  • The test client’s as_tuple parameter is removed. Use response.request.environ instead. #4417

  • Some parameters in send_file and send_from_directory were renamed in 2.0. The deprecation period for the old names is extended to 2.2. Be sure to test with deprecation warnings visible.

  • attachment_filename is renamed to download_name.

  • cache_timeout is renamed to max_age.
  • add_etags is renamed to etag.
  • filename is renamed to path.
  • The RequestContext.g property is deprecated. Use g directly or AppContext.g instead. #3898
  • copy_current_request_context can decorate async functions. #4303
  • The CLI uses importlib.metadata instead of pkg_resources to load command entry points. #4419
  • Overriding FlaskClient.open will not cause an error on redirect. #3396
  • Add an --exclude-patterns option to the flask run CLI command to specify patterns that will be ignored by the reloader. #4188
  • When using lazy loading (the default with the debugger), the Click context from the flask run command remains available in the loader thread. #4460
  • Deleting the session cookie uses the httponly flag. #4485
  • Relax typing for errorhandler to allow the user to use more precise types and decorate the same function multiple times. #4095, #4295, #4297
  • Fix typing for __exit__ methods for better compatibility with ExitStack. #4474
  • From Werkzeug, for redirect responses the Location header URL will remain relative, and exclude the scheme and domain, by default. #4496
  • Add Config.from_prefixed_env() to load config values from environment variables that start with FLASK_ or another prefix. This parses values as JSON by default, and allows setting keys in nested dicts. #4479

Version 2.0.3

Released 2022-02-14

  • The test client’s as_tuple parameter is deprecated and will be removed in Werkzeug 2.1. It is now also deprecated in Flask, to be removed in Flask 2.1, while remaining compatible with both in 2.0.x. Use response.request.environ instead. #4341
  • Fix type annotation for errorhandler decorator. #4295
  • Revert a change to the CLI that caused it to hide ImportError tracebacks when importing the application. #4307
  • app.json_encoder and json_decoder are only passed to dumps and loads if they have custom behavior. This improves performance, mainly on PyPy. #4349
  • Clearer error message when after_this_request is used outside a request context. #4333

Version 2.0.2

Released 2021-10-04

  • Fix type annotation for teardown_* methods. #4093
  • Fix type annotation for before_request and before_app_request decorators. #4104
  • Fixed the issue where typing requires template global decorators to accept functions with no arguments. #4098
  • Support View and MethodView instances with async handlers. #4112
  • Enhance typing of app.errorhandler decorator. #4095
  • Fix registering a blueprint twice with differing names. #4124
  • Fix the type of static_folder to accept pathlib.Path. #4150
  • jsonify handles decimal.Decimal by encoding to str. #4157
  • Correctly handle raising deferred errors in CLI lazy loading. #4096
  • The CLI loader handles **kwargs in a create_app function. #4170
  • Fix the order of before_request and other callbacks that trigger before the view returns. They are called from the app down to the closest nested blueprint. #4229

Version 2.0.1

Released 2021-05-21

  • Re-add the filename parameter in send_from_directory. The filename parameter has been renamed to path, the old name is deprecated. #4019
  • Mark top-level names as exported so type checking understands imports in user projects. #4024
  • Fix type annotation for g and inform mypy that it is a namespace object that has arbitrary attributes. #4020
  • Fix some types that weren’t available in Python 3.6.0. #4040
  • Improve typing for send_file, send_from_directory, and get_send_file_max_age. #4044, #4026
  • Show an error when a blueprint name contains a dot. The . has special meaning, it is used to separate (nested) blueprint names and the endpoint name. #4041
  • Combine URL prefixes when nesting blueprints that were created with a url_prefix value. #4037
  • Revert a change to the order that URL matching was done. The URL is again matched after the session is loaded, so the session is available in custom URL converters. #4053
  • Re-add deprecated Config.from_json, which was accidentally removed early. #4078
  • Improve typing for some functions using Callable in their type signatures, focusing on decorator factories. #4060
  • Nested blueprints are registered with their dotted name. This allows different blueprints with the same name to be nested at different locations. #4069
  • register_blueprint takes a name option to change the (pre-dotted) name the blueprint is registered with. This allows the same blueprint to be registered multiple times with unique names for url_for. Registering the same blueprint with the same name multiple times is deprecated. #1091
  • Improve typing for stream_with_context. #4052

Version 2.0.0

Released 2021-05-11

  • Drop support for Python 2 and 3.5.
  • Bump minimum versions of other Pallets projects: Werkzeug >= 2, Jinja2 >= 3, MarkupSafe >= 2, ItsDangerous >= 2, Click >= 8. Be sure to check the change logs for each project. For better compatibility with other applications (e.g. Celery) that still require Click 7, there is no hard dependency on Click 8 yet, but using Click 7 will trigger a DeprecationWarning and Flask 2.1 will depend on Click 8.
  • JSON support no longer uses simplejson. To use another JSON module, override app.json_encoder and json_decoder. #3555
  • The encoding option to JSON functions is deprecated. #3562
  • Passing script_info to app factory functions is deprecated. This was not portable outside the flask command. Use click.get_current_context().obj if it’s needed. #3552
  • The CLI shows better error messages when the app failed to load when looking up commands. #2741
  • Add SessionInterface.get_cookie_name to allow setting the session cookie name dynamically. #3369
  • Add Config.from_file to load config using arbitrary file loaders, such as toml.load or json.load. Config.from_json is deprecated in favor of this. #3398
  • The flask run command will only defer errors on reload. Errors present during the initial call will cause the server to exit with the traceback immediately. #3431
  • send_file raises a ValueError when passed an io object in text mode. Previously, it would respond with 200 OK and an empty file. #3358
  • When using ad-hoc certificates, check for the cryptography library instead of PyOpenSSL. #3492
  • When specifying a factory function with FLASK_APP, keyword argument can be passed. #3553
  • When loading a .env or .flaskenv file, the current working directory is no longer changed to the location of the file. #3560
  • When returning a (response, headers) tuple from a view, the headers replace rather than extend existing headers on the response. For example, this allows setting the Content-Type for jsonify(). Use response.headers.extend() if extending is desired. #3628
  • The Scaffold class provides a common API for the Flask and Blueprint classes. Blueprint information is stored in attributes just like Flask, rather than opaque lambda functions. This is intended to improve consistency and maintainability. #3215
  • Include samesite and secure options when removing the session cookie. #3726
  • Support passing a pathlib.Path to static_folder. #3579
  • send_file and send_from_directory are wrappers around the implementations in werkzeug.utils. #3828
  • Some send_file parameters have been renamed, the old names are deprecated. attachment_filename is renamed to download_name. cache_timeout is renamed to max_age. add_etags is renamed to etag. #3828, #3883
  • send_file passes download_name even if as_attachment=False by using Content-Disposition: inline. #3828
  • send_file sets conditional=True and max_age=None by default. Cache-Control is set to no-cache if max_age is not set, otherwise public. This tells browsers to validate conditional requests instead of using a timed cache. #3828
  • helpers.safe_join is deprecated. Use werkzeug.utils.safe_join instead. #3828
  • The request context does route matching before opening the session. This could allow a session interface to change behavior based on request.endpoint. #3776
  • Use Jinja’s implementation of the |tojson filter. #3881
  • Add route decorators for common HTTP methods. For example, @app.post("/login") is a shortcut for @app.route("/login", methods=["POST"]). #3907
  • Support async views, error handlers, before and after request, and teardown functions. #3412
  • Support nesting blueprints. #593, #1548, #3923
  • Set the default encoding to “UTF-8” when loading .env and .flaskenv files to allow to use non-ASCII characters. #3931
  • flask shell sets up tab and history completion like the default python shell if readline is installed. #3941
  • helpers.total_seconds() is deprecated. Use timedelta.total_seconds() instead. #3962
  • Add type hinting. #3973.

Version 1.1.4

Released 2021-05-13

  • Update static_folder to use _compat.fspath instead of os.fspath to continue supporting Python < 3.6 #4050

Version 1.1.3

Released 2021-05-13

  • Set maximum versions of Werkzeug, Jinja, Click, and ItsDangerous. #4043
  • Re-add support for passing a pathlib.Path for static_folder. #3579

Version 1.1.2

Released 2020-04-03

  • Work around an issue when running the flask command with an external debugger on Windows. #3297
  • The static route will not catch all URLs if the Flask static_folder argument ends with a slash. #3452

Version 1.1.1

Released 2019-07-08

  • The flask.json_available flag was added back for compatibility with some extensions. It will raise a deprecation warning when used, and will be removed in version 2.0.0. #3288

Version 1.1.0

Released 2019-07-04

  • Bump minimum Werkzeug version to >= 0.15.
  • Drop support for Python 3.4.

  • Error handlers for InternalServerError or 500 will always be passed an instance of InternalServerError. If they are invoked due to an unhandled exception, that original exception is now available as e.original_exception rather than being passed directly to the handler. The same is true if the handler is for the base HTTPException. This makes error handler behavior more consistent. #3266

  • Flask.finalize_request is called for all unhandled exceptions even if there is no 500 error handler.

  • Flask.logger takes the same name as Flask.name (the value passed as Flask(import_name). This reverts 1.0’s behavior of always logging to "flask.app", in order to support multiple apps in the same process. A warning will be shown if old configuration is detected that needs to be moved. #2866
  • RequestContext.copy includes the current session object in the request context copy. This prevents session pointing to an out-of-date object. #2935
  • Using built-in RequestContext, unprintable Unicode characters in Host header will result in a HTTP 400 response and not HTTP 500 as previously. #2994
  • send_file supports PathLike objects as described in PEP 519, to support pathlib in Python 3. #3059
  • send_file supports BytesIO partial content. #2957
  • open_resource accepts the “rt” file mode. This still does the same thing as “r”. #3163
  • The MethodView.methods attribute set in a base class is used by subclasses. #3138
  • Flask.jinja_options is a dict instead of an ImmutableDict to allow easier configuration. Changes must still be made before creating the environment. #3190
  • Flask’s JSONMixin for the request and response wrappers was moved into Werkzeug. Use Werkzeug’s version with Flask-specific support. This bumps the Werkzeug dependency to >= 0.15. #3125
  • The flask command entry point is simplified to take advantage of Werkzeug 0.15’s better reloader support. This bumps the Werkzeug dependency to >= 0.15. #3022
  • Support static_url_path that ends with a forward slash. #3134
  • Support empty static_folder without requiring setting an empty static_url_path as well. #3124
  • jsonify supports dataclass objects. #3195
  • Allow customizing the Flask.url_map_class used for routing. #3069
  • The development server port can be set to 0, which tells the OS to pick an available port. #2926
  • The return value from cli.load_dotenv is more consistent with the documentation. It will return False if python-dotenv is not installed, or if the given path isn’t a file. #2937
  • Signaling support has a stub for the connect_via method when the Blinker library is not installed. #3208
  • Add an --extra-files option to the flask run CLI command to specify extra files that will trigger the reloader on change. #2897
  • Allow returning a dictionary from a view function. Similar to how returning a string will produce a text/html response, returning a dict will call jsonify to produce a application/json response. #3111
  • Blueprints have a cli Click group like app.cli. CLI commands registered with a blueprint will be available as a group under the flask command. #1357.
  • 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. #3157
  • Show a better error message when the view return type is not supported. #3214
  • flask.testing.make_test_environ_builder() has been deprecated in favour of a new class flask.testing.EnvironBuilder. #3232
  • The flask run command no longer fails if Python is not built with SSL support. Using the --cert option will show an appropriate error message. #3211
  • URL matching now occurs after the request context is pushed, rather than when it’s created. This allows custom URL converters to access the app and request contexts, such as to query a database for an id. #3088

Version 1.0.4

Released 2019-07-04

  • The key information for BadRequestKeyError is no longer cleared outside debug mode, so error handlers can still access it. This requires upgrading to Werkzeug 0.15.5. #3249
  • send_file url quotes the “:” and “/” characters for more compatible UTF-8 filename support in some browsers. #3074
  • Fixes for PEP 451 import loaders and pytest 5.x. #3275
  • Show message about dotenv on stderr instead of stdout. #3285

Version 1.0.3

Released 2019-05-17

  • send_file encodes filenames as ASCII instead of Latin-1 (ISO-8859-1). This fixes compatibility with Gunicorn, which is stricter about header encodings than PEP 3333. #2766
  • Allow custom CLIs using FlaskGroup to set the debug flag without it always being overwritten based on environment variables. #2765
  • flask --version outputs Werkzeug’s version and simplifies the Python version. #2825
  • send_file handles an attachment_filename that is a native Python 2 string (bytes) with UTF-8 coded bytes. #2933
  • A catch-all error handler registered for HTTPException will not handle RoutingException, which is used internally during routing. This fixes the unexpected behavior that had been introduced in 1.0. #2986
  • Passing the json argument to app.test_client does not push/pop an extra app context. #2900

Version 1.0.2

Released 2018-05-02

  • Fix more backwards compatibility issues with merging slashes between a blueprint prefix and route. #2748
  • Fix error with flask routes command when there are no routes. #2751

Version 1.0.1

Released 2018-04-29

  • Fix registering partials (with no __name__) as view functions. #2730
  • Don’t treat lists returned from view functions the same as tuples. Only tuples are interpreted as response data. #2736
  • Extra slashes between a blueprint’s url_prefix and a route URL are merged. This fixes some backwards compatibility issues with the change in 1.0. #2731, #2742
  • Only trap BadRequestKeyError errors in debug mode, not all BadRequest errors. This allows abort(400) to continue working as expected. #2735
  • The FLASK_SKIP_DOTENV environment variable can be set to 1 to skip automatically loading dotenv files. #2722

Version 1.0

Released 2018-04-26

  • Python 2.6 and 3.3 are no longer supported.
  • Bump minimum dependency versions to the latest stable versions: Werkzeug >= 0.14, Jinja >= 2.10, itsdangerous >= 0.24, Click >= 5.1. #2586
  • Skip app.run when a Flask application is run from the command line. This avoids some behavior that was confusing to debug.
  • Change the default for JSONIFY_PRETTYPRINT_REGULAR to False. ~json.jsonify returns a compact format by default, and an indented format in debug mode. #2193
  • Flask.__init__ accepts the host_matching argument and sets it on Flask.url_map. #1559
  • Flask.__init__ accepts the static_host argument and passes it as the host argument when defining the static route. #1559
  • send_file supports Unicode in attachment_filename. #2223
  • Pass _scheme argument from url_for to Flask.handle_url_build_error. #2017
  • Flask.add_url_rule accepts the provide_automatic_options argument to disable adding the OPTIONS method. #1489
  • MethodView subclasses inherit method handlers from base classes. #1936
  • Errors caused while opening the session at the beginning of the request are handled by the app’s error handlers. #2254
  • Blueprints gained Blueprint.json_encoder and Blueprint.json_decoder attributes to override the app’s encoder and decoder. #1898
  • Flask.make_response raises TypeError instead of ValueError for bad response types. The error messages have been improved to describe why the type is invalid. #2256
  • Add routes CLI command to output routes registered on the application. #2259
  • Show warning when session cookie domain is a bare hostname or an IP address, as these may not behave properly in some browsers, such as Chrome. #2282
  • Allow IP address as exact session cookie domain. #2282
  • SESSION_COOKIE_DOMAIN is set if it is detected through SERVER_NAME. #2282
  • Auto-detect zero-argument app factory called create_app or make_app from FLASK_APP. #2297
  • Factory functions are not required to take a script_info parameter to work with the flask command. If they take a single parameter or a parameter named script_info, the ScriptInfo object will be passed. #2319
  • FLASK_APP can be set to an app factory, with arguments if needed, for example FLASK_APP=myproject.app:create_app('dev'). #2326
  • FLASK_APP can point to local packages that are not installed in editable mode, although pip install -e is still preferred. #2414
  • The View class attribute View.provide_automatic_options is set in View.as_view, to be detected by Flask.add_url_rule. #2316
  • Error handling will try handlers registered for blueprint, code, app, code, blueprint, exception, app, exception. #2314
  • Cookie is added to the response’s Vary header if the session is accessed at all during the request (and not deleted). #2288
  • Flask.test_request_context accepts subdomain and url_scheme arguments for use when building the base URL. #1621
  • Set APPLICATION_ROOT to '/' by default. This was already the implicit default when it was set to None.
  • TRAP_BAD_REQUEST_ERRORS is enabled by default in debug mode. BadRequestKeyError has a message with the bad key in debug mode instead of the generic bad request message. #2348
  • Allow registering new tags with TaggedJSONSerializer to support storing other types in the session cookie. #2352
  • Only open the session if the request has not been pushed onto the context stack yet. This allows stream_with_context generators to access the same session that the containing view uses. #2354
  • Add json keyword argument for the test client request methods. This will dump the given object as JSON and set the appropriate content type. #2358
  • Extract JSON handling to a mixin applied to both the Request and Response classes. This adds the Response.is_json and Response.get_json methods to the response to make testing JSON response much easier. #2358
  • Removed error handler caching because it caused unexpected results for some exception inheritance hierarchies. Register handlers explicitly for each exception if you want to avoid traversing the MRO. #2362
  • Fix incorrect JSON encoding of aware, non-UTC datetimes. #2374
  • Template auto reloading will honor debug mode even even if Flask.jinja_env was already accessed. #2373

  • The following old deprecated code was removed. #2385

  • flask.ext - import extensions directly by their name instead of through the flask.ext namespace. For example, import flask.ext.sqlalchemy becomes import flask_sqlalchemy.

  • Flask.init_jinja_globals - extend Flask.create_jinja_environment instead.
  • Flask.error_handlers - tracked by Flask.error_handler_spec, use Flask.errorhandler to register handlers.
  • Flask.request_globals_class - use Flask.app_ctx_globals_class instead.
  • Flask.static_path - use Flask.static_url_path instead.
  • Request.module - use Request.blueprint instead.
  • The Request.json property is no longer deprecated. #1421
  • Support passing a EnvironBuilder or dict to test_client.open. #2412
  • The flask command and Flask.run will load environment variables from .env and .flaskenv files if python-dotenv is installed. #2416
  • When passing a full URL to the test client, the scheme in the URL is used instead of PREFERRED_URL_SCHEME. #2430
  • Flask.logger has been simplified. LOGGER_NAME and LOGGER_HANDLER_POLICY config was removed. The logger is always named flask.app. The level is only set on first access, it doesn’t check Flask.debug each time. Only one format is used, not different ones depending on Flask.debug. No handlers are removed, and a handler is only added if no handlers are already configured. #2436
  • Blueprint view function names may not contain dots. #2450
  • Fix a ValueError caused by invalid Range requests in some cases. #2526
  • The development server uses threads by default. #2529
  • Loading config files with silent=True will ignore ENOTDIR errors. #2581
  • Pass --cert and --key options to flask run to run the development server over HTTPS. #2606
  • Added SESSION_COOKIE_SAMESITE to control the SameSite attribute on the session cookie. [#2607

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