daft.functions.try_cast#

def try_cast(expr: Expression, dtype: DataTypeLike) -> Expression:
    """Attempts to cast an expression to the given datatype, returning null on failure.

    Unlike `cast`, this function does not raise an error when the conversion fails.
    Instead, it returns null for values that cannot be converted.

    Returns:
        Expression: Expression with the specified new datatype, with null for failed conversions

    Note:
        - If a string is provided, it will use the sql engine to parse the string into a data type.
        - A python `type` can also be provided, in which case the corresponding Daft data type will be used.

    Examples:
        >>> import daft
        >>> df = daft.from_pydict({"str_val": ["1", "2", "abc", None]})
        >>> df = df.select(df["str_val"].try_cast(daft.DataType.int64()))
        >>> df.show()
        ╭─────────╮
        │ str_val │
        │ ---     │
        │ Int64   │
        ╞═════════╡
        │ 1       │
        ├╌╌╌╌╌╌╌╌╌┤
        │ 2       │
        ├╌╌╌╌╌╌╌╌╌┤
        │ None    │
        ├╌╌╌╌╌╌╌╌╌┤
        │ None    │
        ╰─────────╯
        <BLANKLINE>
        (Showing first 4 of 4 rows)
    """
    dtype = DataType._infer(dtype)
    expr = Expression._to_expression(expr)
    return Expression._from_pyexpr(expr._expr.try_cast(dtype._dtype))