[forms] Fix edition of TZDatetime attributes
Parse the submitted web form values into a timezone-aware datetime
(by default, UTC) when such an attribute is edited. This is done using
an automatically-selected (by `web.formfield.guess_field`) field named
`TZDatetimeField`.
Closes #12666598.
Tutorials
~~~~~~~~~
We present a few tutorials of different levels. The blog building
tutorial introduces one smoothly to the basic concepts.
Then there is a photo gallery construction tutorial which highlights
more advanced concepts such as unit tests, security settings,
migration scripts.
.. toctree::
:maxdepth: 1
base/index
advanced/index
tools/windmill.rst
textreports/index
dataimport/index