feat: expose variety of features from DF54 update

.ai/skills/check-upstream/SKILL.md

@@ -66,11 +66,17 @@ The user may specify an area via `$ARGUMENTS`. If no area is specified or "all"
 - Python API: `python/datafusion/functions.py` — each function wraps a call to `datafusion._internal.functions`
 - Rust bindings: `crates/core/src/functions.rs` — `#[pyfunction]` definitions registered via `init_module()`
 
+**Evaluated and not requiring separate Python exposure:**
+- `get_field_path` — already covered by `get_field(expr, *names)`, which takes a
+  variadic field path and dispatches to the same underlying
+  `functions::core::get_field` UDF as the upstream `get_field_path` helper.
+
 **How to check:**
 1. Fetch the upstream scalar function documentation page
 2. Compare against functions listed in `python/datafusion/functions.py` (check the `__all__` list and function definitions)
 3. A function is covered if it exists in the Python API — it does NOT need a dedicated Rust `#[pyfunction]`. Many functions are aliases that reuse another function's Rust binding.
-4. Only report functions that are missing from the Python `__all__` list / function definitions
+4. Check against the "evaluated and not requiring exposure" list before flagging as a gap
+5. Only report functions that are missing from the Python `__all__` list / function definitions
 
 ### 2. Aggregate Functions
 

crates/core/src/functions.rs

@@ -574,10 +574,10 @@ expr_fn!(union_tag, arg1);
 expr_fn!(random);
 
 #[pyfunction]
-fn get_field(expr: PyExpr, name: PyExpr) -> PyExpr {
-    functions::core::get_field()
-        .call(vec![expr.into(), name.into()])
-        .into()
+fn get_field(expr: PyExpr, names: Vec<PyExpr>) -> PyExpr {
+    let mut args = vec![expr.into()];
+    args.extend(names.into_iter().map(Into::into));
+    functions::core::get_field().call(args).into()
 }
 
 #[pyfunction]

examples/datafusion-ffi-example/src/table_function.rs

@@ -17,9 +17,8 @@
 
 use std::sync::Arc;
 
-use datafusion_catalog::{TableFunctionImpl, TableProvider};
+use datafusion_catalog::{TableFunctionArgs, TableFunctionImpl, TableProvider};
 use datafusion_common::error::Result as DataFusionResult;
-use datafusion_expr::Expr;
 use datafusion_ffi::udtf::FFI_TableFunction;
 use datafusion_python_util::ffi_logical_codec_from_pycapsule;
 use pyo3::types::PyCapsule;
@@ -59,7 +58,7 @@ impl MyTableFunction {
 }
 
 impl TableFunctionImpl for MyTableFunction {
-    fn call(&self, _args: &[Expr]) -> DataFusionResult<Arc<dyn TableProvider>> {
+    fn call_with_args(&self, _args: TableFunctionArgs) -> DataFusionResult<Arc<dyn TableProvider>> {
         let provider = MyTableProvider::new(4, 3, 2).create_table()?;
         Ok(Arc::new(provider))
     }

python/datafusion/context.py

@@ -86,13 +86,16 @@
 
     import pandas as pd
     import polars as pl  # type: ignore[import]
+    from _typeshed import CapsuleType as _PyCapsule
 
     from datafusion.catalog import CatalogProvider, Table
     from datafusion.common import DFSchema
     from datafusion.expr import Expr, SortKey
     from datafusion.plan import ExecutionPlan, LogicalPlan
     from datafusion.user_defined import (
         AggregateUDF,
+        LogicalExtensionCodecExportable,
+        PhysicalExtensionCodecExportable,
         ScalarUDF,
         TableFunction,
         WindowUDF,
@@ -1744,11 +1747,15 @@ def __datafusion_logical_extension_codec__(self) -> Any:
         """Access the PyCapsule FFI_LogicalExtensionCodec."""
         return self.ctx.__datafusion_logical_extension_codec__()
 
-    def with_logical_extension_codec(self, codec: Any) -> SessionContext:
+    def with_logical_extension_codec(
+        self, codec: LogicalExtensionCodecExportable | _PyCapsule
+    ) -> SessionContext:
         """Create a new session context with specified codec.
 
         This only supports codecs that have been implemented using the
-        FFI interface.
+        FFI interface. ``codec`` must either be a raw ``FFI_LogicalExtensionCodec``
+        ``PyCapsule`` or an object exposing
+        ``__datafusion_logical_extension_codec__``.
         """
         new_internal = self.ctx.with_logical_extension_codec(codec)
         new = SessionContext.__new__(SessionContext)
@@ -1759,11 +1766,15 @@ def __datafusion_physical_extension_codec__(self) -> Any:
         """Access the PyCapsule FFI_PhysicalExtensionCodec."""
         return self.ctx.__datafusion_physical_extension_codec__()
 
-    def with_physical_extension_codec(self, codec: Any) -> SessionContext:
+    def with_physical_extension_codec(
+        self, codec: PhysicalExtensionCodecExportable | _PyCapsule
+    ) -> SessionContext:
         """Create a new session context with the specified physical codec.
 
         This only supports codecs that have been implemented using the
-        FFI interface.
+        FFI interface. ``codec`` must either be a raw
+        ``FFI_PhysicalExtensionCodec`` ``PyCapsule`` or an object exposing
+        ``__datafusion_physical_extension_codec__``.
         """
         new_internal = self.ctx.with_physical_extension_codec(codec)
         new = SessionContext.__new__(SessionContext)

python/datafusion/functions.py

@@ -2727,14 +2727,24 @@ def arrow_metadata(expr: Expr, key: Expr | str | None = None) -> Expr:
     return Expr(f.arrow_metadata(expr.expr, key.expr))
 
 
-def get_field(expr: Expr, name: Expr | str) -> Expr:
-    """Extracts a field from a struct or map by name.
+def get_field(expr: Expr, *names: Expr | str) -> Expr:
+    """Extracts a (possibly nested) field from a struct or map by name.
 
-    When the field name is a static string, the bracket operator
-    ``expr["field"]`` is a convenient shorthand. Use ``get_field``
-    when the field name is a dynamic expression.
+    Pass one name for a single-level lookup, or several names to walk a path
+    of nested struct/map fields in a single ``get_field`` call. For a single
+    static-string name, ``expr["field"]`` is a convenient shorthand; use
+    ``get_field`` when the field name is a dynamic
+    :py:class:`~datafusion.expr.Expr` or when traversing multiple levels at
+    once.
+
+    Args:
+        expr: The struct or map expression to read from.
+        *names: One or more field names (``str``) or expressions
+            (:py:class:`~datafusion.expr.Expr`).
 
     Examples:
+        Single-level lookup:
+
         >>> ctx = dfn.SessionContext()
         >>> df = ctx.from_pydict({"a": [1], "b": [2]})
         >>> df = df.with_column(
@@ -2756,10 +2766,26 @@ def get_field(expr: Expr, name: Expr | str) -> Expr:
         ... )
         >>> result.collect_column("x_val")[0].as_py()
         1
+
+        Multi-level lookup:
+
+        >>> df = df.with_column(
+        ...     "outer",
+        ...     dfn.functions.named_struct([("inner", dfn.col("s"))]),
+        ... )
+        >>> result = df.select(
+        ...     dfn.functions.get_field(
+        ...         dfn.col("outer"), "inner", "x"
+        ...     ).alias("x_val")
+        ... )
+        >>> result.collect_column("x_val")[0].as_py()
+        1
     """
-    if isinstance(name, str):
-        name = Expr.string_literal(name)
-    return Expr(f.get_field(expr.expr, name.expr))
+    if not names:
+        msg = "get_field requires at least one field name"
+        raise ValueError(msg)
+    resolved = [Expr.string_literal(n) if isinstance(n, str) else n for n in names]
+    return Expr(f.get_field(expr.expr, [n.expr for n in resolved]))
 
 
 def union_extract(union_expr: Expr, field_name: Expr | str) -> Expr:

python/datafusion/user_defined.py

@@ -113,6 +113,18 @@ def _is_pycapsule(value: object) -> TypeGuard[_PyCapsule]:
     return value.__class__.__name__ == "PyCapsule"
 
 
+class LogicalExtensionCodecExportable(Protocol):
+    """Type hint for objects exposing ``__datafusion_logical_extension_codec__``."""
+
+    def __datafusion_logical_extension_codec__(self) -> object: ...  # noqa: D105
+
+
+class PhysicalExtensionCodecExportable(Protocol):
+    """Type hint for objects exposing ``__datafusion_physical_extension_codec__``."""
+
+    def __datafusion_physical_extension_codec__(self) -> object: ...  # noqa: D105
+
+
 class ScalarUDF:
     """Class for performing scalar user-defined functions (UDF).
 

python/tests/test_functions.py

@@ -1957,6 +1957,37 @@ def test_get_field(df):
     assert result.column(1) == pa.array([4, 5, 6])
 
 
+def test_get_field_path(df):
+    df = df.with_column(
+        "outer",
+        f.named_struct(
+            [
+                (
+                    "inner",
+                    f.named_struct(
+                        [
+                            ("x", column("a")),
+                            ("y", column("b")),
+                        ]
+                    ),
+                ),
+            ]
+        ),
+    )
+    result = df.select(
+        f.get_field(column("outer"), "inner", "x").alias("x_val"),
+        f.get_field(column("outer"), "inner", "y").alias("y_val"),
+    ).collect()[0]
+
+    assert result.column(0) == pa.array(["Hello", "World", "!"], type=pa.string_view())
+    assert result.column(1) == pa.array([4, 5, 6])
+
+
+def test_get_field_requires_a_name():
+    with pytest.raises(ValueError, match="at least one field name"):
+        f.get_field(column("s"))
+
+
 def test_arrow_metadata():
     ctx = SessionContext()
     field = pa.field("val", pa.int64(), metadata={"key1": "value1", "key2": "value2"})