New submission from Richard Neumann <[email protected]>:
I often write factory (deserialization) methods for ORM models for web
application backends that produce a number of records (ORM model instances) of
itself and related database tables:
@classmethod
def from_json(cls, json):
"""Yields records from a JSON-ish dict."""
modules = json.pop('modules', None) or ()
order = super().from_json(json)
yield order
for module in modules:
yield OrderedModule(order=order, module=Module(module))
This yields the main record "order" and related records from OrderedModules,
which have a foreign key to Order.
Thusly I can save all records by:
for record in Order.from_json(json):
record.save()
Since I have several of those deserialization functions for multiple tables in
multiple databases, it'd be nice to reduce the amount of code with some extra
syntactic sugar, like:
@classmethod
def from_json(cls, json):
"""Yields records from a JSON-ish dict."""
modules = json.pop('modules', None) or ()
yield order = super().from_json(json) # Assignment via "="
for module in modules:
yield OrderedModule(order=order, module=Module(module))
or:
@classmethod
def from_json(cls, json):
"""Yields records from a JSON-ish dict."""
modules = json.pop('modules', None) or ()
yield order := super().from_json(json) # Assignment via ":="
for module in modules:
yield OrderedModule(order=order, module=Module(module))
I therefor propose to allow assignment of names in generator-like yield
statements as described above.
----------
messages: 376979
nosy: conqp
priority: normal
severity: normal
status: open
title: Allow assignment in yield statement
type: enhancement
versions: Python 3.10
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Python tracker <[email protected]>
<https://bugs.python.org/issue41795>
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