baumgold commented on issue #285:
URL: https://github.com/apache/arrow-julia/issues/285#issuecomment-1042488559
As a work-around all nullable types can be converted to use Missing instead
of Nothing, which seems to allow Python to read the Arrow files generated by
Arrow.jl. The issue is now we cannot distinguish between nothing (converted to
missing) and actual missing.
```julia
julia> ArrowTypes.ArrowType(::Type{Union{Nothing,T}}) where {T} =
Union{Missing,ArrowTypes.ArrowType(T)}
julia> Arrow.write("/tmp/nothing.arrow",
(col=Vector{Union{Nothing,Int32}}([1,2,3,nothing]),))
"/tmp/nothing.arrow"
julia> Arrow.Table("/tmp/nothing.arrow")
Arrow.Table with 4 rows, 1 columns, and schema:
:col Union{Missing, Int32}
```
```python
In [1]: pandas.read_feather("/tmp/nothing.arrow")
Out[1]:
col
0 1.0
1 2.0
2 3.0
3 NaN
```
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