pitrou commented on code in PR #37797:
URL: https://github.com/apache/arrow/pull/37797#discussion_r1354314764
##########
python/pyarrow/table.pxi:
##########
@@ -2983,6 +2985,100 @@ cdef class RecordBatch(_Tabular):
<ArrowArray*> c_ptr, c_schema))
return pyarrow_wrap_batch(c_batch)
+ def __arrow_c_array__(self, requested_schema=None):
+ """
+ Get a pair of PyCapsules containing a C ArrowArray representation of
the object.
+
+ Parameters
+ ----------
+ requested_schema : PyCapsule | None
+ A PyCapsule containing a C ArrowSchema representation of a
requested
+ schema. PyArrow will attempt to cast the batch to this schema.
+ If None, the schema will be returned as-is, with a schema matching
the
+ one returned by :meth:`__arrow_c_schema__()`.
+
+ Returns
+ -------
+ Tuple[PyCapsule, PyCapsule]
+ A pair of PyCapsules containing a C ArrowSchema and ArrowArray,
+ respectively.
+ """
+ cdef:
+ ArrowArray* c_array
+ ArrowSchema* c_schema
+
+ if requested_schema is not None:
+ target_schema = Schema._import_from_c_capsule(requested_schema)
+
+ if target_schema != self.schema:
+ try:
+ # We don't expose .cast() on RecordBatch, only on Table.
+ casted_batch = Table.from_batches([self]).cast(
+ target_schema, safe=True).to_batches()[0]
+ inner_batch = pyarrow_unwrap_batch(casted_batch)
+ except ArrowInvalid as e:
+ raise ValueError(
+ f"Could not cast {self.schema} to requested schema
{target_schema}"
Review Comment:
I don't know, but it doesn't help if one merely prints the exception
message. Here, we are really re-raising the original error with a bit more
context in the exception message, so IMHO it makes sense to keep the original
message as well.
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