daft.functions.json_array_length#

def json_array_length(expr: Expression) -> Expression:
    """Returns the number of elements in the outermost JSON array.

    Returns ``NULL`` when the input is ``NULL``, cannot be parsed as JSON,
    or the parsed JSON is not an array. Equivalent to Spark's
    ``json_array_length``.

    Args:
        expr: A string expression containing JSON.

    Returns:
        Expression: An ``Int32`` expression with the array length.

    Examples:
        >>> import daft
        >>> from daft.functions import json_array_length
        >>>
        >>> df = daft.from_pydict({"col": ["[1, 2, 3]", "[]", '{"a": 1}', None]})
        >>> df.with_column("len", json_array_length(df["col"])).collect()
        ╭───────────┬───────╮
        │ col       ┆ len   │
        │ ---       ┆ ---   │
        │ String    ┆ Int32 │
        ╞═══════════╪═══════╡
        │ [1, 2, 3] ┆ 3     │
        ├╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ []        ┆ 0     │
        ├╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ {"a": 1}  ┆ None  │
        ├╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
        │ None      ┆ None  │
        ╰───────────┴───────╯
        <BLANKLINE>
        (Showing first 4 of 4 rows)
    """
    return Expression._call_builtin_scalar_fn("json_array_length", expr)