.. _logging-fstring-interpolation:

logging-fstring-interpolation / W1203
=====================================

**Message emitted:**

``Use %s formatting in logging functions``

**Description:**

*Used when a logging statement has a call form of "logging.<logging method>(f"...")".Use another type of string formatting instead. You can use % formatting but leave interpolation to the logging function by passing the parameters as arguments. If logging-format-interpolation is disabled then you can use str.format. If logging-not-lazy is disabled then you can use % formatting as normal.*

**Problematic code:**

.. literalinclude:: /data/messages/l/logging-fstring-interpolation/bad.py
   :language: python

**Correct code:**

.. literalinclude:: /data/messages/l/logging-fstring-interpolation/good.py
   :language: python


**Additional details:**

This message permits to allow f-string in logging and still be warned of
``logging-format-interpolation``.

**Related links:**

- `logging variable data <https://docs.python.org/3/howto/logging.html#logging-variable-data>`_
- `Rationale <https://stackoverflow.com/questions/34619790>`_


Created by the `logging <https://github.com/pylint-dev/pylint/blob/main/pylint/checkers/logging.py>`__ checker.