[R] Possible undesirable handling of POSIXlt objects

[asfimport]

In the course of updating documentation, I noticed that it is possible to create an Arrow array of POSIXlt objects from R, but not a scalar.

#14514 (comment)

This works:

tm <- as.POSIXlt(c(Sys.time(), Sys.time()))
arrow::Array$create(tm)

This fails:

arrow::Scalar$create(as.POSIXlt(Sys.time()))

It's possible to manually convert a POSIXlt object to a struct scalar like this:

df <- as.data.frame(unclass(as.POSIXlt(Sys.time())))
arrow::Scalar$create(df, 
              type = struct(
                sec = float32(), 
                min = int32(),
                hour = int32(),
                mday = int32(),
                mon = int32(),
                year = int32(),
                wday = int32(),
                yday = int32(),
                isdst = int32(),
                zone = utf8(),
                gmtoff = int32()
              ))

although this does not seem precisely the same as the behaviour of Array$create() which creates an extension type?

It was unclear to us ( @thisisnic and myself) whether the current behaviour was desirable, so it seemed sensible to open an issue!

Related issue:

https://issues.apache.org/jira/browse/ARROW-18263

Reporter: Danielle Navarro / @djnavarro
Assignee: Dewey Dunnington / @paleolimbot

PRs and other links:

• GitHub Pull Request #15277

_{Note: This issue was originally created as ARROW-18337. Please see the migration documentation for further details.}

[asfimport]

Dewey Dunnington / @paleolimbot:
Oooof...this is particularly bad since it causes a crash (for me):

/Users/dewey/Desktop/rscratch/arrow/cpp/src/arrow/result.cc:28: ValueOrDie called on an error: NotImplemented: construction from scalar of type POSIXlt of length 0

The error seems to be coming from the ValueOrDie here: https://github.com/apache/arrow/blob/master/cpp/src/arrow/scalar.cc#L785-L803

I tried a rudimentary approach of an RExtensionScalar subclass but didn't get anywhere because Scalar::ToString() is not virtual (i.e., I can't provide a more reasonable method without exposing an additional R6 class at the R level).

[asfimport]

Dewey Dunnington / @paleolimbot:
The backtrace of the ValueOrDie is:

/Users/dewey/Desktop/rscratch/arrow/cpp/src/arrow/result.cc:28: ValueOrDie called on an error: NotImplemented: construction from scalar of type POSIXlt of length 0
/Users/dewey/Desktop/rscratch/arrow/cpp/src/arrow/array/util.cc:545  VisitTypeInline(*scalar_.type, this)
0   libarrow.1100.0.0.dylib             0x000000011b3a9d0c _ZN5arrow4util7CerrLogD2Ev + 236
1   libarrow.1100.0.0.dylib             0x000000011b3a9c18 _ZN5arrow4util7CerrLogD0Ev + 12
2   libarrow.1100.0.0.dylib             0x000000011b3a9bb4 _ZN5arrow4util8ArrowLogD1Ev + 48
3   libarrow.1100.0.0.dylib             0x000000011b2862a0 _ZN5arrow8internal17InvalidValueOrDieERKNS_6StatusE + 244
4   libarrow.1100.0.0.dylib             0x000000011b28a0d8 _ZNK5arrow6Scalar8ToStringEv + 792
5   arrow.so                            0x000000010c064fac _arrow_Scalar__ToString + 108
6   libR.dylib                          0x0000000102f89be4 R_doDotCall + 1572

[raulcd]

This has been merged pointing to the original issue. I am closing the issue manually. Should we update the merge script to not allow merging issues pointing to JIRA so we have to update the titles? I already created a PR to update the title check on the PR: #33611

[assignUser]

@raulcd yes I think that makes sense