davlee1972 opened a new issue, #45936:
URL: https://github.com/apache/arrow/issues/45936
### Describe the enhancement requested
This impacts pyarrow.compute.cast() and reading pyarrow datasets using
schemas for Text and Json files.
It also impacts SQL result sets which return string values for date/datetime
columns. (Tested using ADBC).
Can we add some string to date32 and date64 conversions which strips the
time portion from YYYY-MM-DD HH:MM:SS.ffff??
For Json YYYY-MM-DD can only be converted to timestamp[s]. This is
inconsistent with the CSV reader which will by default converts YYYY-MM-DD into
date32..
```
>>> import pyarrow.compute as pc
>>> import pyarrow.dataset as ds
>>>
>>> # This works
>>> today = pa.scalar('2025-03-24')
>>> pc.cast(today, "date32")
<pyarrow.Date32Scalar: datetime.date(2025, 3, 24)>
>>> pc.cast(today, "timestamp[s]").cast("date32")
<pyarrow.Date32Scalar: datetime.date(2025, 3, 24)>
>>>
>>> # This works if you cast first to timestamp
>>> today = pa.scalar('2025-03-24 00:00:00')
>>> pc.cast(today, "date32")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/u1/leed/miniconda3/lib/python3.9/site-packages/pyarrow/compute.py",
line 405, in cast
return call_function("cast", [arr], options, memory_pool)
File "pyarrow/_compute.pyx", line 598, in pyarrow._compute.call_function
File "pyarrow/_compute.pyx", line 393, in pyarrow._compute.Function.call
File "pyarrow/error.pxi", line 155, in
pyarrow.lib.pyarrow_internal_check_status
File "pyarrow/error.pxi", line 92, in pyarrow.lib.check_status
pyarrow.lib.ArrowInvalid: Failed to parse string: '2025-03-24 00:00:00' as a
scalar of type date32[day]
>>> pc.cast(today, "timestamp[s]").cast("date32")
<pyarrow.Date32Scalar: datetime.date(2025, 3, 24)>
>>>
>>> # For text you also can't parse dates with 00:00:00 into dates
>>> with open("test.csv", "w") as f:
... f.write("today\n")
... f.write("2025-03-24 00:00:00\n")
... f.write("2025-03-24 00:00:00\n")
... f.write("2025-03-24 00:00:00\n")
...
6
20
20
20
>>> text_dataset = ds.dataset("test.csv", format="csv",
schema=pa.schema([pa.field("today", "date32")]))
>>> text_dataset.schema
today: date32[day]
>>> text_dataset.head(10)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pyarrow/_dataset.pyx", line 730, in pyarrow._dataset.Dataset.head
File "pyarrow/_dataset.pyx", line 3911, in pyarrow._dataset.Scanner.head
File "pyarrow/error.pxi", line 155, in
pyarrow.lib.pyarrow_internal_check_status
File "pyarrow/error.pxi", line 92, in pyarrow.lib.check_status
pyarrow.lib.ArrowInvalid: Could not open CSV input source 'test.csv':
Invalid: In CSV column #0: Row #2: CSV conversion error to date32[day]: invalid
value '2025-03-24 00:00:00'
>>>
>>> # JSON only supports timestamps.
>>> with open("test.json", "w") as f:
... f.write('{"today": "2025-03-24"}\n')
... f.write('{"today": "2025-03-24"}\n')
... f.write('{"today": "2025-03-24"}\n')
...
24
24
24
>>> json_dataset = ds.dataset("test.json", format="json",
schema=pa.schema([pa.field("today", "date32")]))
>>> json_dataset.schema
today: date32[day]
>>> json_dataset.head(10)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "pyarrow/_dataset.pyx", line 730, in pyarrow._dataset.Dataset.head
File "pyarrow/_dataset.pyx", line 3911, in pyarrow._dataset.Scanner.head
File "pyarrow/error.pxi", line 155, in
pyarrow.lib.pyarrow_internal_check_status
File "pyarrow/error.pxi", line 92, in pyarrow.lib.check_status
pyarrow.lib.ArrowInvalid: Could not open JSON input source 'test.json':
Invalid: JSON parse error: Column(/today) changed from number to string in row 0
>>>
>>> json_dataset = ds.dataset("test.json", format="json")
>>> json_dataset.schema
today: timestamp[s]
>>> json_dataset.head(10)
pyarrow.Table
today: timestamp[s]
----
today: [[2025-03-24 00:00:00,2025-03-24 00:00:00,2025-03-24 00:00:00]]
```
### Component(s)
C++, Python
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