How to pass a Pandas DataFrame to Julia in 0.9?

[mind6]

I have a pyconvert_add_rule in Julia that accepts a Py object wrapping pandas DataFrame, reads its columns, wraps PyArray around each column, add it to Julia DataFrame, all without copying. So I'm able to fetch a pandas DataFrame from inside Julia.

But I'm not able to activate this chain trying to pass from Python to Julia. It converts the pandas DataFrame to a PyObject instead of PyPandasDataFrame. I overrode convert rule to accept PyObject, but it seems to have trouble accessing its columns. I get the following RuntimeError trying to convert it:

In [9]: jl.convert(DataFrames.DataFrame, bm1)
---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
Input In [9], in <cell line: 1>()
----> 1 jl.convert(DataFrames.DataFrame, bm1)

RuntimeError: <PyCall.jlwrap (in a Julia function called from Python)
JULIA: UndefRefError: access to undefined reference
Stacktrace:
  [1] PyType_IsSubtype
    @ C:\Users\kirby\.julia\packages\PythonCall\4eoCM\src\cpython\pointers.jl:297 [inlined]
  [2] PyJuliaValue_New(t::Ptr{PythonCall.C.PyObject}, v::Any)
    @ PythonCall.C C:\Users\kirby\.julia\packages\PythonCall\4eoCM\src\cpython\jlwrap.jl:314
  [3] pyjl
    @ C:\Users\kirby\.julia\packages\PythonCall\4eoCM\src\jlwrap\base.jl:7 [inlined]
  [4] pyjl
    @ C:\Users\kirby\.julia\packages\PythonCall\4eoCM\src\jlwrap\any.jl:321 [inlined]
  [5] Py
    @ C:\Users\kirby\.julia\packages\PythonCall\4eoCM\src\Py.jl:157 [inlined]
  [6] macro expansion
    @ C:\Users\kirby\.julia\packages\PythonCall\4eoCM\src\Py.jl:136 [inlined]
  [7] pyconvert(#unused#::Type{DataFrames.DataFrame}, x::PyObject)
    @ PythonCall C:\Users\kirby\.julia\packages\PythonCall\4eoCM\src\convert.jl:370
  [8] convert(#unused#::Type{DataFrames.DataFrame}, x::PyObject)
    @ Conversions C:\Users\kirby\MyDrive\Documents\thirdwave\julia\Conversions.jl:27
  [9] invokelatest(::Any, ::Any, ::Vararg{Any}; kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ Base .\essentials.jl:716
 [10] invokelatest(::Any, ::Any, ::Vararg{Any})
    @ Base .\essentials.jl:714
 [11] _pyjlwrap_call(f::Function, args_::Ptr{PyCall.PyObject_struct}, kw_::Ptr{PyCall.PyObject_struct})
    @ PyCall C:\Users\kirby\.julia\packages\PyCall\7a7w0\src\callback.jl:28
 [12] pyjlwrap_call(self_::Ptr{PyCall.PyObject_struct}, args_::Ptr{PyCall.PyObject_struct}, kw_::Ptr{PyCall.PyObject_struct})
    @ PyCall C:\Users\kirby\.julia\packages\PyCall\7a7w0\src\callback.jl:44>

[mind6]

This was caused by confusing from julia import Main as jl with from juliacall import Main as jl. If you're using JuliaCall make sure you're using the second form. The first one is for the older pyjulia which hasn't had updates for two years.