Tell if object isinstance of PyDatetime or Pydate?

Question

Here's my main.rs file:

use pyo3::prelude::*;
use pyo3::types::{PyDateTime, PyDate};

fn main() -> () {
    Python::with_gil(|py| {
        let datetime = py.import("datetime").unwrap();
        let my_datetime = datetime.call_method1("datetime", (2022, 3, 28, 0, 0, 0, 0)).unwrap();
        println!("isinstance pydatetime: {:?}", my_datetime.is_instance_of::<PyDateTime>().unwrap());
        println!("isinstance pydate: {:?}", my_datetime.is_instance_of::<PyDate>().unwrap());

        let my_date = datetime.call_method1("date", (2022, 3, 28)).unwrap();
        println!("isinstance pydatetime: {:?}", my_date.is_instance_of::<PyDateTime>().unwrap());
        println!("isinstance pydate: {:?}", my_date.is_instance_of::<PyDate>().unwrap());
    })
}

Here's my Cargo.toml file:

[package]
name = "tmp"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
pyo3 = { version = "0.18.0", features = ["auto-initialize"] }

If I run the above, I get

isinstance pydatetime: true
isinstance pydate: true
isinstance pydatetime: true
isinstance pydate: true

I find this a bit odd, because running in Python directly, I get:

In [27]: import datetime as dt

In [28]: isinstance(my_datetime, dt.datetime)
Out[28]: True

In [29]: isinstance(my_datetime, dt.date)
Out[29]: True

In [30]: isinstance(my_date, dt.datetime)
Out[30]: False

In [31]: isinstance(my_date, dt.date)
Out[31]: True

So, I would have expected

my_date.is_instance_of::<PyDateTime>().unwrap()

to also be false

Why is that not the case, and how can I distinguish between whether an object is datetime or date without resorting to more hacky methods like checking dt.get_type().name()?

You might want to report this to pyo3 because there's something really wrong happening: I tried going through [PyTypeInfo](https://pyo3.rs/main/doc/pyo3/type_object/trait.pytypeinfo) and PyO3-level types for initialisation to avoid getting lost with Python-level types, and both `PyDate` and `PyDateTime` are reported as being the type of a `PyDateTime::new` result but neither is reported to be its exact type, and PyDate is even weirder: `PyDateTime::is_exact_type_of(my_date)` returns `true`, but `PyDateTime::is_type_of(my_date)` returns `false`. — Masklinn, Mar 27 '23 at 15:22
Even getting the Python-level `isinstance` from the builtins, I still get `True` when asking if `my_date` is an instance of `datetime`. — Masklinn, Mar 27 '23 at 15:32
My pull request has been accepted, so this should be fixed in the next version: https://github.com/PyO3/pyo3/pull/3071 — Solomon Ucko, Mar 28 '23 at 19:16

score 3 · Accepted Answer · answered Mar 27 '23 at 18:44

I've submitted a pull request to PyO3 that should fix this: https://github.com/PyO3/pyo3/pull/3071

diff --git a/src/types/datetime.rs b/src/types/datetime.rs
index 85860728568..2c995356e2c 100644
--- a/src/types/datetime.rs
+++ b/src/types/datetime.rs
@@ -228,7 +228,7 @@ pub struct PyDateTime(PyAny);
 pyobject_native_type!(
     PyDateTime,
     crate::ffi::PyDateTime_DateTime,
-    *ensure_datetime_api(Python::assume_gil_acquired()).DateType,
+    *ensure_datetime_api(Python::assume_gil_acquired()).DateTimeType,
     #module=Some("datetime"),
     #checkfunction=PyDateTime_Check
 );

Tell if object isinstance of PyDatetime or Pydate?

1 Answers1