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Streamline serialization for migrations
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Trying to avoid uncessary creation of migrations.
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@mfogel
mfogel committed Feb 8, 2022
1 parent 74f8612 commit 93fc011
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Showing 2 changed files with 97 additions and 107 deletions.
161 changes: 79 additions & 82 deletions tests/test_deconstruct.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,70 +5,40 @@
from timezone_field import TimeZoneField
from timezone_field.compat import ZoneInfo


@pytest.fixture
def fields(use_pytz):
return (
TimeZoneField(use_pytz=use_pytz),
TimeZoneField(default="UTC", use_pytz=use_pytz),
TimeZoneField(max_length=42, use_pytz=use_pytz),
TimeZoneField(
choices=[
(pytz.timezone("US/Pacific"), "US/Pacific"),
(pytz.timezone("US/Eastern"), "US/Eastern"),
],
use_pytz=use_pytz,
),
TimeZoneField(
choices=[
(pytz.timezone(b"US/Pacific"), b"US/Pacific"),
(pytz.timezone(b"US/Eastern"), b"US/Eastern"),
],
use_pytz=use_pytz,
),
TimeZoneField(
choices=[
("US/Pacific", "US/Pacific"),
("US/Eastern", "US/Eastern"),
],
use_pytz=use_pytz,
),
TimeZoneField(
choices=[
(b"US/Pacific", b"US/Pacific"),
(b"US/Eastern", b"US/Eastern"),
],
use_pytz=use_pytz,
),
)


def test_deconstruct(fields, use_pytz):
if not use_pytz:
fields += (
TimeZoneField(
choices=[
(ZoneInfo("US/Pacific"), "US/Pacific"),
(ZoneInfo("US/Eastern"), "US/Eastern"),
],
use_pytz=use_pytz,
),
)
for org_field in fields:
_name, _path, args, kwargs = org_field.deconstruct()
new_field = TimeZoneField(*args, use_pytz=use_pytz, **kwargs)
assert org_field.max_length == new_field.max_length
assert org_field.choices == new_field.choices


def test_full_serialization(fields):
test_fields = [
TimeZoneField(),
TimeZoneField(default="UTC"),
TimeZoneField(max_length=42),
TimeZoneField(use_pytz=True),
TimeZoneField(use_pytz=False),
TimeZoneField(choices=[("US/Pacific", "US/Pacific"), ("US/Eastern", "US/Eastern")]),
TimeZoneField(choices=[(b"US/Pacific", b"US/Pacific"), (b"US/Eastern", b"US/Eastern")]),
TimeZoneField(
choices=[(pytz.timezone("US/Pacific"), "US/Pacific"), (pytz.timezone("US/Eastern"), "US/Eastern")],
use_pytz=True,
),
TimeZoneField(
choices=[(ZoneInfo("US/Pacific"), "US/Pacific"), (ZoneInfo("US/Eastern"), "US/Eastern")],
use_pytz=False,
),
]


@pytest.mark.parametrize("field", test_fields)
def test_deconstruct(field):
_name, _path, args, kwargs = field.deconstruct()
new_field = TimeZoneField(*args, **kwargs)
assert field.max_length == new_field.max_length
assert field.choices == new_field.choices


@pytest.mark.parametrize("field", test_fields)
def test_full_serialization(field):
# ensure the values passed to kwarg arguments can be serialized
# the recommended 'deconstruct' testing by django docs doesn't cut it
# https://docs.djangoproject.com/en/1.7/howto/custom-model-fields/#field-deconstruction
# replicates https://github.com/mfogel/django-timezone-field/issues/12
for field in fields:
# ensuring the following call doesn't throw an error
MigrationWriter.serialize(field)
MigrationWriter.serialize(field) # should not throw


def test_from_db_value(use_pytz):
Expand All @@ -82,51 +52,64 @@ def test_from_db_value(use_pytz):
assert utc == value


def test_default_kwargs_not_frozen(use_pytz):
def test_default_kwargs_not_frozen():
"""
Ensure the deconstructed representation of the field does not contain
kwargs if they match the default.
Don't want to bloat everyone's migration files.
"""
field = TimeZoneField(use_pytz=use_pytz)
field = TimeZoneField()
_name, _path, _args, kwargs = field.deconstruct()
assert "choices" not in kwargs
assert "max_length" not in kwargs


def test_specifying_defaults_not_frozen(use_pytz, tz_func):
def test_specifying_defaults_not_frozen():
"""
If someone's matched the default values with their kwarg args, we
shouldn't bothering freezing those.
shouldn't bothering freezing those
(excluding the use_pytz, which changes with your django version).
"""
field = TimeZoneField(max_length=63, use_pytz=use_pytz)
field = TimeZoneField(max_length=63)
_name, _path, _args, kwargs = field.deconstruct()
assert "max_length" not in kwargs

choices = [(tz_func(tz), tz.replace("_", " ")) for tz in pytz.common_timezones]
field = TimeZoneField(choices=choices, use_pytz=use_pytz)
choices = [(tz, tz.replace("_", " ")) for tz in pytz.common_timezones]
field = TimeZoneField(choices=choices)
_name, _path, _args, kwargs = field.deconstruct()
assert "choices" not in kwargs

choices = [(tz, tz.replace("_", " ")) for tz in pytz.common_timezones]
field = TimeZoneField(choices=choices, use_pytz=use_pytz)
choices = [(pytz.timezone(tz), tz.replace("_", " ")) for tz in pytz.common_timezones]
field = TimeZoneField(choices=choices, use_pytz=True)
_name, _path, _args, kwargs = field.deconstruct()
assert "choices" not in kwargs

choices = [(ZoneInfo(tz), tz.replace("_", " ")) for tz in pytz.common_timezones]
field = TimeZoneField(choices=choices, use_pytz=False)
_name, _path, _args, kwargs = field.deconstruct()
assert "choices" not in kwargs


@pytest.mark.parametrize(
"use_tz_object, timezones",
"choices, use_pytz",
[
[True, ["US/Pacific", "US/Eastern"]],
[False, ["US/Pacific", "US/Eastern"]],
[
[("US/Pacific", "US/Pacific"), ("US/Eastern", "US/Eastern")],
None,
],
[
[(pytz.timezone("US/Pacific"), "US/Pacific"), (pytz.timezone("US/Eastern"), "US/Eastern")],
True,
],
[
[(ZoneInfo("US/Pacific"), "US/Pacific"), (ZoneInfo("US/Eastern"), "US/Eastern")],
False,
],
],
)
def test_deconstruct_when_using_just_choices(use_tz_object, timezones, use_pytz, tz_func):
if not use_tz_object:
tz_func = str
choices = [(tz_func(tz), tz) for tz in timezones]
field = TimeZoneField(choices=choices, use_pytz=use_pytz)
_name, _path, _args, kwargs = field.deconstruct()
def test_deconstruct_when_using_choices(choices, use_pytz):
field = TimeZoneField(choices=choices)
_name, _path, args, kwargs = field.deconstruct()
assert kwargs == {
"choices": [
("US/Pacific", "US/Pacific"),
Expand All @@ -143,8 +126,8 @@ def test_deconstruct_when_using_just_choices(use_tz_object, timezones, use_pytz,
["WITH_GMT_OFFSET", {"choices_display": "WITH_GMT_OFFSET"}],
],
)
def test_deconstruct_when_using_just_choices_display(use_pytz, choices_display, expected_kwargs):
field = TimeZoneField(choices_display=choices_display, use_pytz=use_pytz)
def test_deconstruct_when_using_choices_display(choices_display, expected_kwargs):
field = TimeZoneField(choices_display=choices_display)
_name, _path, _args, kwargs = field.deconstruct()
assert kwargs == expected_kwargs

Expand Down Expand Up @@ -174,7 +157,21 @@ def test_deconstruct_when_using_just_choices_display(use_pytz, choices_display,
],
],
)
def test_deconstruct_when_using_choices_and_choices_display(use_pytz, choices, choices_display, expected_kwargs):
field = TimeZoneField(choices=choices, choices_display=choices_display, use_pytz=use_pytz)
def test_deconstruct_when_using_choices_and_choices_display(choices, choices_display, expected_kwargs):
field = TimeZoneField(choices=choices, choices_display=choices_display)
_name, _path, _args, kwargs = field.deconstruct()
assert kwargs == expected_kwargs


@pytest.mark.parametrize(
"use_pytz, expected_kwargs",
[
[None, {}],
[True, {"use_pytz": True}],
[False, {"use_pytz": False}],
],
)
def test_deconstruct_when_using_use_pytz(use_pytz, expected_kwargs):
field = TimeZoneField(use_pytz=use_pytz)
_name, _path, _args, kwargs = field.deconstruct()
assert kwargs == expected_kwargs
43 changes: 18 additions & 25 deletions timezone_field/fields.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,11 +7,6 @@
from timezone_field.compat import ZoneInfo, ZoneInfoNotFoundError
from timezone_field.utils import is_pytz_instance, use_pytz_default

default_pytz_tzs = [pytz.timezone(tz) for tz in pytz.common_timezones]
default_pytz_choices = standard(default_pytz_tzs)
default_zoneinfo_tzs = [ZoneInfo(tz) for tz in pytz.common_timezones]
default_zoneinfo_choices = standard(default_zoneinfo_tzs)


class TimeZoneField(models.Field):
"""
Expand Down Expand Up @@ -42,18 +37,20 @@ class TimeZoneField(models.Field):
# NOTE: these defaults are excluded from migrations. If these are changed,
# existing migration files will need to be accomodated.
default_max_length = 63
default_pytz_tzs = [pytz.timezone(tz) for tz in pytz.common_timezones]
default_zoneinfo_tzs = [ZoneInfo(tz) for tz in pytz.common_timezones]

def __init__(self, *args, **kwargs):
# allow some use of positional args up until the args we customize
# https://github.com/mfogel/django-timezone-field/issues/42
# https://github.com/django/django/blob/1.11.11/django/db/models/fields/__init__.py#L145
if len(args) > 3:
raise ValueError("Cannot specify max_length by positional arg")
kwargs.setdefault("max_length", self.default_max_length)
self.use_pytz = kwargs.pop("use_pytz", use_pytz_default())

self.default_tzs = default_pytz_tzs if self.use_pytz else default_zoneinfo_tzs
self.default_choices = default_pytz_choices if self.use_pytz else default_zoneinfo_choices
self.max_length = kwargs.pop("max_length", self.default_max_length)
self.use_pytz_explicit = kwargs.pop("use_pytz", None)
self.use_pytz = self.use_pytz_explicit if self.use_pytz_explicit is not None else use_pytz_default()
self.default_tzs = self.default_pytz_tzs if self.use_pytz else self.default_zoneinfo_tzs

if "choices" in kwargs:
values, displays = zip(*kwargs["choices"])
Expand Down Expand Up @@ -100,26 +97,22 @@ def deconstruct(self):
if kwargs.get("max_length") == self.default_max_length:
del kwargs["max_length"]

if self.use_pytz_explicit is not None:
kwargs["use_pytz"] = self.use_pytz_explicit

if self.choices_display is not None:
kwargs["choices_display"] = self.choices_display

choices = kwargs.get("choices")
if choices:
if self.choices_display is None:
defaults = [default_pytz_choices]
if default_zoneinfo_tzs:
defaults += [default_zoneinfo_choices]
if choices == self.default_choices:
kwargs.pop("choices")
choices = kwargs["choices"]
if self.choices_display is None:
if choices == standard(self.default_tzs):
kwargs.pop("choices")
else:
values, _ = zip(*choices)
if sorted(values, key=str) == sorted(self.default_tzs, key=str):
kwargs.pop("choices")
else:
values, _ = zip(*choices)
defaults = [default_pytz_tzs]
if default_zoneinfo_tzs:
defaults += [default_zoneinfo_tzs]
if sorted(values, key=str) in defaults:
kwargs.pop("choices")
else:
kwargs["choices"] = [(value, "") for value in values]
kwargs["choices"] = [(value, "") for value in values]

# django can't decontruct pytz objects, so transform choices
# to [<str>, <str>] format for writing out to the migration
Expand Down

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