Version 1.1.1
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.
Version 1.1.0
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.
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.
flask.RequestContext.copy() includes the current session object in the request context copy. This prevents session pointing to an out-of-date object.
Using built-in RequestContext, unprintable Unicode characters in Host header will result in a HTTP 400 response and not HTTP 500 as previously.
send_file() supports PathLike objects as described in PEP 0519, to support pathlib in Python 3.
send_file() supports BytesIO partial content.
open_resource() accepts the “rt” file mode. This still does the same thing as “r”.
The MethodView.methods attribute set in a base class is used by subclasses.
Flask.jinja_options is a dict instead of an ImmutableDict to allow easier configuration. Changes must still be made before creating the environment.
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.
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.
Support static_url_path that ends with a forward slash.
Support empty static_folder without requiring setting an empty static_url_path as well.
jsonify() supports dataclasses.dataclass objects.
Allow customizing the Flask.url_map_class used for routing.
The development server port can be set to 0, which tells the OS to pick an available port.
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.
Signaling support has a stub for the connect_via method when the Blinker library is not installed.
Add an --extra-files option to the flask run CLI command to specify extra files that will trigger the reloader on change.
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.
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..
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.
Show a better error message when the view return type is not supported.
flask.testing.make_test_environ_builder() has been deprecated in favour of a new class flask.testing.EnvironBuilder.
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.
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.
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