examples/datafusion-ffi-example/python/tests/_test_scalar_udf.py

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from __future__ import annotations

import pyarrow as pa
from datafusion import SessionContext, col, udf
from datafusion_ffi_example import IsNullUDF


def setup_context_with_table():
    ctx = SessionContext()

    batch = pa.RecordBatch.from_arrays(
        [pa.array([1, 2, 3, None])],
        names=["a"],
    )
    ctx.register_record_batches("test_table", [[batch]])
    return ctx


def test_ffi_scalar_register():
    ctx = setup_context_with_table()
    my_udf = udf(IsNullUDF())
    ctx.register_udf(my_udf)

    result = ctx.sql("select my_custom_is_null(a) from test_table").collect()

    assert len(result) == 1
    assert result[0].num_columns == 1
    print(result)

    result = [r.column(0) for r in result]
    expected = [
        pa.array([False, False, False, True], type=pa.bool_()),
    ]

    assert result == expected


def test_ffi_scalar_call_directly():
    ctx = setup_context_with_table()
    my_udf = udf(IsNullUDF())

    result = ctx.table("test_table").select(my_udf(col("a"))).collect()

    assert len(result) == 1
    assert result[0].num_columns == 1
    print(result)

    result = [r.column(0) for r in result]
    expected = [
        pa.array([False, False, False, True], type=pa.bool_()),
    ]

    assert result == expected