How can I use a case expression from Python?

[mesejo]

According to the User Guide one of the conditional expressions available is case:

CASE expression. Example: case(expr).when(expr, expr).when(expr, expr).otherwise(expr).end()

However, the Python module does not expose a case function, it does expose a Case class, but I could not find any documentation on how to use it.

The Case class has no constructor. For example:

df = df.select(
    Case(col("a")).when(datafusion.lit(3)).then(datafusion.lit(3))
)

gives:

Traceback (most recent call last):
  File "/datafusion-demo/main.py", line 20, in <module>
    Case(col("a")).when(datafusion.lit(3)).then(datafusion.lit(3))
TypeError: No constructor defined 

Also:

df = df.select(
    col("a").when(datafusion.lit(3)).then(datafusion.lit(3))
)

gives:

AttributeError: 'datafusion.expr.Expr' object has no attribute 'when'

PS:

The repository for the Python bindings has no discussions and I could not find a suitable example here.

Curious fact is that the nullif expression is exposed under the functions module.

[alamb]

I am sorry I don't know about the python bindings, but the rust function is here: https://docs.rs/datafusion/latest/datafusion/logical_expr/fn.case.html

Maybe it needs to be exposed via the python bindings?