Not possible to seed uuid4

[J535D165]

It is not possible to seed the uuid4 property.

>>> f1 = Faker()
>>> f1.seed(4321)
>>> print(f1.uuid4())
4a6d35db-b61b-49ed-a225-e16bc164f7cc

>>> f2 = Faker()
>>> f2.seed(4321)
>>> print(f2.uuid4())
b5f05be8-2f57-4a52-9b6f-5bcd03125278

The solution is pretty much given in:
http://stackoverflow.com/questions/41186818/how-to-generate-a-random-uuid-which-is-reproducible-with-a-seed-in-python

[fcurella]

Thank you for the report, good catch!

Would you mind submit a Pull Request?

[J535D165]

The same issue for Faker.binary().

I am working on a unit test for the seeding part. But there is another issue that needs a fix first.

[fcurella]

Closed in #486

@J535D165 can you open a separate issue for seeding .binary()?

[fcurella]

reopened so I can close it when we have tests

[kevin-brown]

It was mentioned on Stack Overflow, but the patch doesn't guarantee that the generated UUID is version 4 (which is what uuid4 generates).

[J535D165]

@kevin-brown I do agree that this is not a valid uuid4. Nevertheless, the format is UUID (32 alphanumeric characters and four hyphens). So I don't think there is an issue.

[fcurella]

@J535D165 @kevin-brown the method is called uuid4, not uuid, so I think users might expect to get a valid uuid4 after all.

That said, I"m still not sure if there is a way that we can fix it, or that we should. If python's uuid4 doesn't return an uuid4 under some conditions, wouldn't this be a bug in Python?

[kevin-brown]

That said, I"m still not sure if there is a way that we can fix it, or that we should. If python's uuid4 doesn't return an uuid4 under some conditions, wouldn't this be a bug in Python?

It's not that Python's uuid4 doesn't return a UUIDv4 identifier, it's that the pull request which added the ability to seed uuid4 in Faker does not always generate a valid UUIDv4 identifier.

[J535D165]

@kevin-brown Do you know how to make it valid?

Is it correct that you can't see a difference between an (incorrect) UUID4 in Faker and a valid UUID4?

[kevin-brown]

Is it correct that you can't see a difference between an (incorrect) UUID4 in Faker and a valid UUID4?

That is not correct. And 15/16 times it will produce a UUID that is not version 4.

>>> u = uuid.UUID(int=random.getrandbits(128))
>>> u
UUID('7119ccd3-e9be-c160-8d0d-608e5f5ea285')
>>> u.version
12

There are a total of 8 bits that must be set manually in order for it to be properly detected as a UUIDv4.

>>> uuid.UUID(int=(random.getrandbits(128) | (1<<63) | (1<<78)) & (~(1<<79) & ~(1<<77) & ~(1<<76) & ~(1<<62))).version
4
>>> uuid.UUID(int=(random.getrandbits(128) | (1<<63) | (1<<78)) & (~(1<<79) & ~(1<<77) & ~(1<<76) & ~(1<<62))).version
4
>>> uuid.UUID(int=(random.getrandbits(128) | (1<<63) | (1<<78)) & (~(1<<79) & ~(1<<77) & ~(1<<76) & ~(1<<62))).version
4
>>> uuid.UUID(int=(random.getrandbits(128) | (1<<63) | (1<<78)) & (~(1<<79) & ~(1<<77) & ~(1<<76) & ~(1<<62))).version
4
>>> uuid.UUID(int=(random.getrandbits(128) | (1<<63) | (1<<78)) & (~(1<<79) & ~(1<<77) & ~(1<<76) & ~(1<<62))).version
4

[michaelvilensky]

I think we should revert the pull request to return the original functionality for uuid4 as it currently breaks things.
For seed support another method can be added: uuid or uuid_seed which will implement the pull request logic: str(uuid.UUID(int=random.getrandbits(128)))

[J535D165]

Let's revert it or use the version proposed by Kevin.

But can you explain me what breaks?

[kungfoome]

Kevins solution appears to work properly. @kevin-brown can you create a pull request, I don't see any currently to update this.

[MarkJB]

Was this fixed? I'm not able to create deterministic UUIDs with Faker-4.17.1

for _ in range(10):
     random_seed = 1234
     baseline_fake = Faker()
     baseline_fake.seed(random_seed)
     expected_uuids = [baseline_fake.uuid4() for i in range(1000)]
     new_fake = Faker()
     new_fake.seed(random_seed)
     new_uuids = [new_fake.uuid4() for i in range(1000)]
     assert new_uuids == expected_uuids
     
Traceback (most recent call last):
  File "<input>", line 4, in <module>
  File "C:\code\sdk_unit_test\venv\lib\site-packages\faker\proxy.py", line 89, in __getattribute__
    raise TypeError(msg)
TypeError: Calling '.seed()' on instances is deprecated. Use the class method 'Faker.seed()' instead.

from faker import Faker
Faker.seed(123)
my_fake = Faker()
my_second_fake = Faker()
my_fake.uuid4()
'c4da537c-1651-4dae-8486-7db30d67b366'
my_second_fake.uuid4()
'd6a82a95-1b92-4e0a-843c-def36840ff07'

[kevin-brown]

The tests which were added in #1050 (and closed out this ticket) are still in the repo at

faker/tests/providers/test_misc.py

Lines 68 to 75 in 594d344

	def test_uuid4_seedability(self, faker, num_samples):
	for _ in range(num_samples):
	random_seed = faker.random_int()
	faker.seed_instance(random_seed)
	expected_uuids = [faker.uuid4() for _ in range(100)]
	faker.seed_instance(random_seed)
	new_uuids = [faker.uuid4() for _ in range(100)]
	assert new_uuids == expected_uuids

I don't use Faker anymore, but after looking at the code it looks like it should now work with seeding and properly return v4 UUIDs.

[MarkJB]

.seed_instance() was what I was missing.

I followed the link to the commit in #1050 and the tests were using .seed() which was what was thowing me.