uuid.py

"""
Adapted from https://github.com/lukesneeringer/django-pgfields/blob/master/django_pg/models/fields/uuid.py

Copyright (c) 2013, Luke Sneeringer
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of the django-pgfields nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL AUTHORS BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""
import importlib
from uuid import UUID, uuid4

from django.db import models
from django.db.models.fields import NOT_PROVIDED
from psycopg2.extensions import register_adapter

from sentry.db.models.utils import Creator


# Adapted from django-pgfields
# https://github.com/lukesneeringer/django-pgfields/blob/master/django_pg/models/fields/uuid.py
class UUIDField(models.Field):
    """Field for storing UUIDs."""

    description = "Universally unique identifier."

    def __init__(self, auto_add=False, coerce_to=UUID, **kwargs):
        """Instantiate the field."""

        # If the `auto_add` argument is specified as True, substitute an
        # appropriate callable which requires no arguments and will return
        # a UUID.
        if auto_add is True:
            auto_add = uuid4

        # If the `auto_add` arguments is specified as a string
        # parse out and import the callable.
        if isinstance(auto_add, str):
            module_name, member = auto_add.split(":")
            module = importlib.import_module(module_name)
            auto_add = getattr(module, member)

        # Save the `auto_add` and `coerce_to` rules.
        self._auto_add = auto_add
        self._coerce_to = coerce_to

        # If `auto_add` is enabled, it should imply that the field
        # is not editable, and should not show up in ModelForms.
        if auto_add and "editable" not in kwargs:
            kwargs["editable"] = False

        # Blank values shall be nulls.
        if kwargs.get("blank", False) and not kwargs.get("null", False):
            raise AttributeError(
                " ".join(
                    (
                        "Blank UUIDs are stored as NULL. Therefore, setting",
                        "`blank` to True requires `null` to be True.",
                    )
                )
            )

        # Enforce CHAR(32) for unsupported engines
        kwargs["max_length"] = 32

        # Now pass the rest of the work to CharField.
        super().__init__(**kwargs)

    def db_type(self, connection):
        return "uuid"

    def get_internal_type(self):
        return "CharField"

    def get_prep_value(self, value):
        """Return a wrapped, valid UUID value."""

        # If the value is None, return None.
        if not value:
            if self.null or self._auto_add or (self.default != NOT_PROVIDED):
                return None
            raise ValueError(
                "Explicit UUID required unless either `null` is " "True or `auto_add` is given."
            )

        # If we already have a UUID, pass it through.
        if isinstance(value, UUID):
            return value

        # Convert our value to a UUID.
        return UUID(value)

    def pre_save(self, instance, add):
        """If auto is set, generate a UUID at random."""

        # If the `auto_add` option was set, and there is no value
        # on the model instance, then generate a UUID using the given
        # callable.
        if self._auto_add and add and not getattr(instance, self.attname):
            uuid_value = self._auto_add()

            # Save the UUID to the model instance
            setattr(instance, self.attname, uuid_value)
            return uuid_value

        # This is the standard case; just use the superclass logic.
        return super().pre_save(instance, add)

    def contribute_to_class(self, cls, name):
        super().contribute_to_class(cls, name)
        setattr(cls, name, Creator(self))

    def to_python(self, value):
        """Return a UUID object."""
        if isinstance(value, self._coerce_to) or not value:
            return value
        return self._coerce_to(value)

    @property
    def _auto_add_str(self):
        """Return a dot path, as a string, of the `_auto_add` callable.
        If `_auto_add` is a boolean, return it unchanged.
        """
        if isinstance(self._auto_add, bool):
            return self._auto_add
        return f"{self._auto_add.__module__}:{self._auto_add.__name__}"


class UUIDAdapter:
    def __init__(self, value):
        if not isinstance(value, UUID):
            raise TypeError("UUIDAdapter only understands UUID objects.")
        self.value = value

    def getquoted(self):
        return ("'%s'" % self.value).encode("utf8")


# Register the UUID type with psycopg2.
register_adapter(UUID, UUIDAdapter)