/
models.py
609 lines (531 loc) · 22.1 KB
/
models.py
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from __future__ import unicode_literals
import copy
import importlib
import threading
import uuid
import warnings
import django
import six
from django.apps import apps
from django.conf import settings
from django.contrib import admin
from django.contrib.auth import get_user_model
from django.core.exceptions import ObjectDoesNotExist
from django.db import models
from django.db.models import Q
from django.db.models.fields.proxy import OrderWrt
from django.forms.models import model_to_dict
from django.urls import reverse
from django.utils.text import format_lazy
from django.utils.timezone import now
from simple_history import utils
from . import exceptions
from .manager import HistoryDescriptor
from .signals import post_create_historical_record, pre_create_historical_record
if django.VERSION < (2,):
from django.utils.translation import ugettext_lazy as _
from django.utils.encoding import smart_text as smart_str
from django.utils.encoding import python_2_unicode_compatible
else:
from django.utils.translation import gettext_lazy as _
from django.utils.encoding import smart_str
registered_models = {}
def _default_get_user(request, **kwargs):
try:
return request.user
except AttributeError:
return None
def _history_user_getter(historical_instance):
if historical_instance.history_user_id is None:
return None
User = get_user_model()
try:
return User.objects.get(pk=historical_instance.history_user_id)
except User.DoesNotExist:
return None
def _history_user_setter(historical_instance, user):
if user is not None:
historical_instance.history_user_id = user.pk
class HistoricalRecords(object):
thread = threading.local()
def __init__(
self,
verbose_name=None,
bases=(models.Model,),
user_related_name="+",
table_name=None,
inherit=False,
excluded_fields=None,
history_id_field=None,
history_change_reason_field=None,
user_model=None,
get_user=_default_get_user,
cascade_delete_history=False,
custom_model_name=None,
app=None,
history_user_id_field=None,
history_user_getter=_history_user_getter,
history_user_setter=_history_user_setter,
related_name=None,
use_base_model_db=False,
):
self.user_set_verbose_name = verbose_name
self.user_related_name = user_related_name
self.table_name = table_name
self.inherit = inherit
self.history_id_field = history_id_field
self.history_change_reason_field = history_change_reason_field
self.user_model = user_model
self.get_user = get_user
self.cascade_delete_history = cascade_delete_history
self.custom_model_name = custom_model_name
self.app = app
self.user_id_field = history_user_id_field
self.user_getter = history_user_getter
self.user_setter = history_user_setter
self.related_name = related_name
self.use_base_model_db = use_base_model_db
if excluded_fields is None:
excluded_fields = []
self.excluded_fields = excluded_fields
try:
if isinstance(bases, six.string_types):
raise TypeError
self.bases = (HistoricalChanges,) + tuple(bases)
except TypeError:
raise TypeError("The `bases` option must be a list or a tuple.")
def contribute_to_class(self, cls, name):
self.manager_name = name
self.module = cls.__module__
self.cls = cls
models.signals.class_prepared.connect(self.finalize, weak=False)
self.add_extra_methods(cls)
if cls._meta.abstract and not self.inherit:
msg = (
"HistoricalRecords added to abstract model ({}) without "
"inherit=True".format(self.cls.__name__)
)
warnings.warn(msg, UserWarning)
def add_extra_methods(self, cls):
def save_without_historical_record(self, *args, **kwargs):
"""
Save model without saving a historical record
Make sure you know what you're doing before you use this method.
"""
self.skip_history_when_saving = True
try:
ret = self.save(*args, **kwargs)
finally:
del self.skip_history_when_saving
return ret
setattr(cls, "save_without_historical_record", save_without_historical_record)
def finalize(self, sender, **kwargs):
inherited = False
if self.cls is not sender: # set in concrete
inherited = self.inherit and issubclass(sender, self.cls)
if not inherited:
return # set in abstract
if hasattr(sender._meta, "simple_history_manager_attribute"):
raise exceptions.MultipleRegistrationsError(
"{}.{} registered multiple times for history tracking.".format(
sender._meta.app_label, sender._meta.object_name
)
)
history_model = self.create_history_model(sender, inherited)
if inherited:
# Make sure history model is in same module as concrete model
module = importlib.import_module(history_model.__module__)
else:
module = importlib.import_module(self.module)
setattr(module, history_model.__name__, history_model)
# The HistoricalRecords object will be discarded,
# so the signal handlers can't use weak references.
models.signals.post_save.connect(self.post_save, sender=sender, weak=False)
models.signals.post_delete.connect(self.post_delete, sender=sender, weak=False)
descriptor = HistoryDescriptor(history_model)
setattr(sender, self.manager_name, descriptor)
sender._meta.simple_history_manager_attribute = self.manager_name
def get_history_model_name(self, model):
if not self.custom_model_name:
return "Historical{}".format(model._meta.object_name)
# Must be trying to use a custom history model name
if callable(self.custom_model_name):
name = self.custom_model_name(model._meta.object_name)
else:
# simple string
name = self.custom_model_name
# Desired class name cannot be same as the model it is tracking
if not (
name.lower() == model._meta.object_name.lower()
and model.__module__ == self.module
):
return name
raise ValueError(
"The 'custom_model_name' option '{}' evaluates to a name that is the same "
"as the model it is tracking. This is not permitted.".format(
self.custom_model_name
)
)
def create_history_model(self, model, inherited):
"""
Creates a historical model to associate with the model provided.
"""
attrs = {
"__module__": self.module,
"_history_excluded_fields": self.excluded_fields,
}
app_module = "%s.models" % model._meta.app_label
if inherited:
# inherited use models module
attrs["__module__"] = model.__module__
elif model.__module__ != self.module:
# registered under different app
attrs["__module__"] = self.module
elif app_module != self.module:
# Abuse an internal API because the app registry is loading.
app = apps.app_configs[model._meta.app_label]
models_module = app.name
attrs["__module__"] = models_module
fields = self.copy_fields(model)
attrs.update(fields)
attrs.update(self.get_extra_fields(model, fields))
# type in python2 wants str as a first argument
attrs.update(Meta=type(str("Meta"), (), self.get_meta_options(model)))
if self.table_name is not None:
attrs["Meta"].db_table = self.table_name
# Set as the default then check for overrides
name = self.get_history_model_name(model)
registered_models[model._meta.db_table] = model
history_model = type(str(name), self.bases, attrs)
return (
python_2_unicode_compatible(history_model)
if django.VERSION < (2,)
else history_model
)
def fields_included(self, model):
fields = []
for field in model._meta.fields:
if field.name not in self.excluded_fields:
fields.append(field)
return fields
def copy_fields(self, model):
"""
Creates copies of the model's original fields, returning
a dictionary mapping field name to copied field object.
"""
fields = {}
for field in self.fields_included(model):
field = copy.copy(field)
field.remote_field = copy.copy(field.remote_field)
if isinstance(field, OrderWrt):
# OrderWrt is a proxy field, switch to a plain IntegerField
field.__class__ = models.IntegerField
if isinstance(field, models.ForeignKey):
old_field = field
old_swappable = old_field.swappable
old_field.swappable = False
try:
_name, _path, args, field_args = old_field.deconstruct()
finally:
old_field.swappable = old_swappable
if getattr(old_field, "one_to_one", False) or isinstance(
old_field, models.OneToOneField
):
FieldType = models.ForeignKey
else:
FieldType = type(old_field)
# If field_args['to'] is 'self' then we have a case where the object
# has a foreign key to itself. If we pass the historical record's
# field to = 'self', the foreign key will point to an historical
# record rather than the base record. We can use old_field.model here.
if field_args.get("to", None) == "self":
field_args["to"] = old_field.model
# Override certain arguments passed when creating the field
# so that they work for the historical field.
field_args.update(
db_constraint=False,
related_name="+",
null=True,
blank=True,
primary_key=False,
db_index=True,
serialize=True,
unique=False,
on_delete=models.DO_NOTHING,
)
field = FieldType(*args, **field_args)
field.name = old_field.name
else:
transform_field(field)
fields[field.name] = field
return fields
def _get_history_change_reason_field(self):
if self.history_change_reason_field:
# User specific field from init
history_change_reason_field = self.history_change_reason_field
elif getattr(
settings, "SIMPLE_HISTORY_HISTORY_CHANGE_REASON_USE_TEXT_FIELD", False
):
# Use text field with no max length, not enforced by DB anyways
history_change_reason_field = models.TextField(null=True)
else:
# Current default, with max length
history_change_reason_field = models.CharField(max_length=100, null=True)
return history_change_reason_field
def _get_history_id_field(self):
if self.history_id_field:
history_id_field = self.history_id_field
history_id_field.primary_key = True
history_id_field.editable = False
elif getattr(settings, "SIMPLE_HISTORY_HISTORY_ID_USE_UUID", False):
history_id_field = models.UUIDField(
primary_key=True, default=uuid.uuid4, editable=False
)
else:
history_id_field = models.AutoField(primary_key=True)
return history_id_field
def _get_history_user_fields(self):
if self.user_id_field is not None:
# Tracking user using explicit id rather than Django ForeignKey
history_user_fields = {
"history_user": property(self.user_getter, self.user_setter),
"history_user_id": self.user_id_field,
}
else:
user_model = self.user_model or getattr(
settings, "AUTH_USER_MODEL", "auth.User"
)
history_user_fields = {
"history_user": models.ForeignKey(
user_model,
null=True,
related_name=self.user_related_name,
on_delete=models.SET_NULL,
)
}
return history_user_fields
def _get_history_related_field(self, model):
if self.related_name:
if self.manager_name == self.related_name:
raise exceptions.RelatedNameConflictError(
"The related name must not be called like the history manager."
)
return {
"history_relation": models.ForeignKey(
model,
on_delete=models.DO_NOTHING,
related_name=self.related_name,
db_constraint=False,
)
}
else:
return {}
def get_extra_fields(self, model, fields):
"""Return dict of extra fields added to the historical record model"""
def revert_url(self):
"""URL for this change in the default admin site."""
opts = model._meta
app_label, model_name = opts.app_label, opts.model_name
return reverse(
"%s:%s_%s_simple_history" % (admin.site.name, app_label, model_name),
args=[getattr(self, opts.pk.attname), self.history_id],
)
def get_instance(self):
attrs = {
field.attname: getattr(self, field.attname) for field in fields.values()
}
if self._history_excluded_fields:
excluded_attnames = [
model._meta.get_field(field).attname
for field in self._history_excluded_fields
]
try:
values = (
model.objects.filter(pk=getattr(self, model._meta.pk.attname))
.values(*excluded_attnames)
.get()
)
except ObjectDoesNotExist:
pass
else:
attrs.update(values)
return model(**attrs)
def get_next_record(self):
"""
Get the next history record for the instance. `None` if last.
"""
history = utils.get_history_manager_for_model(self.instance)
return (
history.filter(Q(history_date__gt=self.history_date))
.order_by("history_date")
.first()
)
def get_prev_record(self):
"""
Get the previous history record for the instance. `None` if first.
"""
history = utils.get_history_manager_for_model(self.instance)
return (
history.filter(Q(history_date__lt=self.history_date))
.order_by("history_date")
.last()
)
extra_fields = {
"history_id": self._get_history_id_field(),
"history_date": models.DateTimeField(),
"history_change_reason": self._get_history_change_reason_field(),
"history_type": models.CharField(
max_length=1,
choices=(("+", _("Created")), ("~", _("Changed")), ("-", _("Deleted"))),
),
"history_object": HistoricalObjectDescriptor(
model, self.fields_included(model)
),
"instance": property(get_instance),
"instance_type": model,
"next_record": property(get_next_record),
"prev_record": property(get_prev_record),
"revert_url": revert_url,
"__str__": lambda self: "{} as of {}".format(
self.history_object, self.history_date
),
}
extra_fields.update(self._get_history_related_field(model))
extra_fields.update(self._get_history_user_fields())
return extra_fields
def get_meta_options(self, model):
"""
Returns a dictionary of fields that will be added to
the Meta inner class of the historical record model.
"""
meta_fields = {
"ordering": ("-history_date", "-history_id"),
"get_latest_by": "history_date",
}
if self.user_set_verbose_name:
name = self.user_set_verbose_name
else:
name = format_lazy("historical {}", smart_str(model._meta.verbose_name))
meta_fields["verbose_name"] = name
if self.app:
meta_fields["app_label"] = self.app
return meta_fields
def post_save(self, instance, created, using=None, **kwargs):
if not created and hasattr(instance, "skip_history_when_saving"):
return
if not kwargs.get("raw", False):
self.create_historical_record(instance, created and "+" or "~", using=using)
def post_delete(self, instance, using=None, **kwargs):
if self.cascade_delete_history:
manager = getattr(instance, self.manager_name)
manager.using(using).all().delete()
else:
self.create_historical_record(instance, "-", using=using)
def create_historical_record(self, instance, history_type, using=None):
using = using if self.use_base_model_db else None
history_date = getattr(instance, "_history_date", now())
history_user = self.get_history_user(instance)
history_change_reason = getattr(instance, "changeReason", None)
manager = getattr(instance, self.manager_name)
attrs = {}
for field in self.fields_included(instance):
attrs[field.attname] = getattr(instance, field.attname)
relation_field = getattr(manager.model, "history_relation", None)
if relation_field is not None:
attrs["history_relation"] = instance
history_instance = manager.model(
history_date=history_date,
history_type=history_type,
history_user=history_user,
history_change_reason=history_change_reason,
**attrs
)
pre_create_historical_record.send(
sender=manager.model,
instance=instance,
history_date=history_date,
history_user=history_user,
history_change_reason=history_change_reason,
history_instance=history_instance,
using=using,
)
history_instance.save(using=using)
post_create_historical_record.send(
sender=manager.model,
instance=instance,
history_instance=history_instance,
history_date=history_date,
history_user=history_user,
history_change_reason=history_change_reason,
using=using,
)
def get_history_user(self, instance):
"""Get the modifying user from instance or middleware."""
try:
return instance._history_user
except AttributeError:
request = None
try:
if self.thread.request.user.is_authenticated:
request = self.thread.request
except AttributeError:
pass
return self.get_user(instance=instance, request=request)
def transform_field(field):
"""Customize field appropriately for use in historical model"""
field.name = field.attname
if isinstance(field, models.BigAutoField):
field.__class__ = models.BigIntegerField
elif isinstance(field, models.AutoField):
field.__class__ = models.IntegerField
elif isinstance(field, models.FileField):
# Don't copy file, just path.
field.__class__ = models.TextField
# Historical instance shouldn't change create/update timestamps
field.auto_now = False
field.auto_now_add = False
if field.primary_key or field.unique:
# Unique fields can no longer be guaranteed unique,
# but they should still be indexed for faster lookups.
field.primary_key = False
field._unique = False
field.db_index = True
field.serialize = True
class HistoricalObjectDescriptor(object):
def __init__(self, model, fields_included):
self.model = model
self.fields_included = fields_included
def __get__(self, instance, owner):
values = {f.attname: getattr(instance, f.attname) for f in self.fields_included}
return self.model(**values)
class HistoricalChanges(object):
def diff_against(self, old_history):
if not isinstance(old_history, type(self)):
raise TypeError(
("unsupported type(s) for diffing: " "'{}' and '{}'").format(
type(self), type(old_history)
)
)
changes = []
changed_fields = []
old_values = model_to_dict(old_history.instance)
current_values = model_to_dict(self.instance)
for field, new_value in current_values.items():
if field in old_values:
old_value = old_values[field]
if old_value != new_value:
change = ModelChange(field, old_value, new_value)
changes.append(change)
changed_fields.append(field)
return ModelDelta(changes, changed_fields, old_history, self)
class ModelChange(object):
def __init__(self, field_name, old_value, new_value):
self.field = field_name
self.old = old_value
self.new = new_value
class ModelDelta(object):
def __init__(self, changes, changed_fields, old_record, new_record):
self.changes = changes
self.changed_fields = changed_fields
self.old_record = old_record
self.new_record = new_record