feat(api): make struct metadata more convenient to access

ibis/expr/types/structs.py

@@ -2,10 +2,12 @@
 
 import collections
 import itertools
-from typing import TYPE_CHECKING, Iterable, Mapping
+from typing import TYPE_CHECKING, Iterable, Mapping, Sequence
 
+from cached_property import cached_property
 from public import public
 
+from ibis import util
 from ibis.expr.types.generic import Column, Scalar, Value, literal
 from ibis.expr.types.typing import V
 
@@ -78,6 +80,21 @@ def __getitem__(self, name: str) -> ir.Value:
 
         return ops.StructField(self, name).to_expr().name(name)
 
+    @cached_property
+    def names(self) -> Sequence[str]:
+        """Return the field names of the struct."""
+        return self.type().names
+
+    @cached_property
+    def types(self) -> Sequence[dt.DataType]:
+        """Return the field types of the struct."""
+        return self.type().types
+
+    @cached_property
+    def fields(self) -> Mapping[str, dt.DataType]:
+        """Return a mapping from field name to field type of the struct."""
+        return util.frozendict(self.type().pairs)
+
     def destructure(self) -> DestructValue:
         """Destructure `self` into a `DestructValue`.
 

ibis/tests/expr/test_value_exprs.py

@@ -1524,3 +1524,23 @@ def test_non_null_with_null_precedence(expr_fn, expected_type):
     t = ibis.table(dict(a="int64", b="!string"), name="t")
     expr = expr_fn(t)
     assert expr.type() == expected_type
+
+
+@pytest.mark.parametrize(
+    ("name", "expected"),
+    [
+        ("names", ("a", "b", "c")),
+        ("types", (dt.int8, dt.string, dt.Array(dt.Array(dt.float64)))),
+        (
+            "fields",
+            ibis.util.frozendict(
+                a=dt.int8,
+                b=dt.string,
+                c=dt.Array(dt.Array(dt.float64)),
+            ),
+        ),
+    ],
+)
+def test_struct_names_types_fields(name, expected):
+    s = ibis.struct(dict(a=1, b="2", c=[[1.0], [], [None]]))
+    assert getattr(s, name) == expected