Type Casting string to date does not for list of dicts #12900
Description
Checks
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I have checked that this issue has not already been reported.
-
I have confirmed this bug exists on the latest version of Polars.
Reproducible example
import polars as pl
pl.DataFrame([{'test':'2023-11-08'}], schema={'test':pl.Date})Log output
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/ahayler/miniforge3/lib/python3.10/os.py", line 685, in __setitem__
value = self.encodevalue(value)
File "/Users/ahayler/miniforge3/lib/python3.10/os.py", line 757, in encode
raise TypeError("str expected, not %s" % type(value).__name__)
TypeError: str expected, not int
>>> os.environ["POLARS_VERBOSE"]="1"
>>> pl.DataFrame([{'test':'2023-11-08'}], schema={'test':pl.Date})
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/Users/ahayler/miniforge3/lib/python3.10/site-packages/polars/dataframe/frame.py", line 368, in __init__
self._df = sequence_to_pydf(
File "/Users/ahayler/miniforge3/lib/python3.10/site-packages/polars/utils/_construction.py", line 940, in sequence_to_pydf
return _sequence_to_pydf_dispatcher(
File "/Users/ahayler/miniforge3/lib/python3.10/functools.py", line 889, in wrapper
return dispatch(args[0].__class__)(*args, **kw)
File "/Users/ahayler/miniforge3/lib/python3.10/site-packages/polars/utils/_construction.py", line 1159, in _sequence_of_dict_to_pydf
pydf = PyDataFrame.read_dicts(
polars.exceptions.ComputeError: could not append value: "2023-11-08" of type: str to the builder; make sure that all rows have the same schema or consider increasing `infer_schema_length`
it might also be that a value overflows the data-type's capacityIssue description
This issue occurs when I try to parse strings as dates into a polars DataFrame from a list of dicts. Removing the list wrapper from the code above creates the expected DataFrame.
Expected behavior
A one row, one column dataframe with '2023-11-08' in column 'test' of dtype pl.Date.
Installed versions
Details
--------Version info---------
Polars: 0.19.19
Index type: UInt32
Platform: macOS-13.2.1-arm64-arm-64bit
Python: 3.10.12 | packaged by conda-forge | (main, Jun 23 2023, 22:41:52) [Clang 15.0.7 ]
----Optional dependencies----
adbc_driver_manager: <not installed>
cloudpickle: <not installed>
connectorx: <not installed>
deltalake: <not installed>
fsspec: <not installed>
gevent: <not installed>
matplotlib: <not installed>
numpy: <not installed>
openpyxl: <not installed>
pandas: <not installed>
pyarrow: <not installed>
pydantic: <not installed>
pyiceberg: <not installed>
pyxlsb: <not installed>
sqlalchemy: <not installed>
xlsx2csv: <not installed>
xlsxwriter: <not installed>