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

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from __future__ import annotations

from typing import TYPE_CHECKING

import pyarrow as pa
from datafusion import Expr, SessionContext, udtf
from datafusion_ffi_example import MyTableFunction, MyTableProvider

if TYPE_CHECKING:
    from datafusion.context import TableProviderExportable


def test_ffi_table_function_register():
    ctx = SessionContext()
    table_func = MyTableFunction()
    table_udtf = udtf(table_func, "my_table_func")
    ctx.register_udtf(table_udtf)
    result = ctx.sql("select * from my_table_func()").collect()

    assert len(result) == 2
    assert result[0].num_columns == 4
    print(result)

    result = [r.column(0) for r in result]
    expected = [
        pa.array([0, 1, 2], type=pa.int32()),
        pa.array([3, 4, 5, 6], type=pa.int32()),
    ]

    assert result == expected


def test_ffi_table_function_call_directly():
    ctx = SessionContext()
    table_func = MyTableFunction()
    table_udtf = udtf(table_func, "my_table_func")

    my_table = table_udtf()
    ctx.register_table_provider("t", my_table)
    result = ctx.table("t").collect()

    assert len(result) == 2
    assert result[0].num_columns == 4
    print(result)

    result = [r.column(0) for r in result]
    expected = [
        pa.array([0, 1, 2], type=pa.int32()),
        pa.array([3, 4, 5, 6], type=pa.int32()),
    ]

    assert result == expected


class PythonTableFunction:
    """Python based table function.

    This class is used as a Python implementation of a table function.
    We use the existing TableProvider to create the underlying
    provider, and this function takes no arguments
    """

    def __call__(
        self, num_cols: Expr, num_rows: Expr, num_batches: Expr
    ) -> TableProviderExportable:
        args = [
            num_cols.to_variant().value_i64(),
            num_rows.to_variant().value_i64(),
            num_batches.to_variant().value_i64(),
        ]
        return MyTableProvider(*args)


def common_table_function_test(test_ctx: SessionContext) -> None:
    result = test_ctx.sql("select * from my_table_func(3,2,4)").collect()

    assert len(result) == 4
    assert result[0].num_columns == 3
    print(result)

    result = [r.column(0) for r in result]
    expected = [
        pa.array([0, 1], type=pa.int32()),
        pa.array([2, 3, 4], type=pa.int32()),
        pa.array([4, 5, 6, 7], type=pa.int32()),
        pa.array([6, 7, 8, 9, 10], type=pa.int32()),
    ]

    assert result == expected


def test_python_table_function():
    ctx = SessionContext()
    table_func = PythonTableFunction()
    table_udtf = udtf(table_func, "my_table_func")
    ctx.register_udtf(table_udtf)

    common_table_function_test(ctx)


def test_python_table_function_decorator():
    ctx = SessionContext()

    @udtf("my_table_func")
    def my_udtf(
        num_cols: Expr, num_rows: Expr, num_batches: Expr
    ) -> TableProviderExportable:
        args = [
            num_cols.to_variant().value_i64(),
            num_rows.to_variant().value_i64(),
            num_batches.to_variant().value_i64(),
        ]
        return MyTableProvider(*args)

    ctx.register_udtf(my_udtf)

    common_table_function_test(ctx)