From b6e464592a840027d4cd4392b086a041802f65d1 Mon Sep 17 00:00:00 2001
From: Michael-J-Ward <ward.michael.j@gmail.com>
Date: Sat, 10 Aug 2024 15:33:41 -0500
Subject: [PATCH] deprecate Expr::display_name

Ref: https://github.com/apache/datafusion/pull/11797
---
 python/datafusion/expr.py            | 11 ++++++++++-
 python/datafusion/tests/test_expr.py | 20 ++++++++++++++++++++
 src/expr.rs                          |  2 +-
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/python/datafusion/expr.py b/python/datafusion/expr.py
index 78acee31b..1733e69ac 100644
--- a/python/datafusion/expr.py
+++ b/python/datafusion/expr.py
@@ -29,6 +29,7 @@
 )
 from datafusion.common import NullTreatment, RexType, DataTypeMap
 from typing import Any, Optional, Type
+from typing_extensions import deprecated
 import pyarrow as pa
 
 # The following are imported from the internal representation. We may choose to
@@ -195,12 +196,20 @@ def to_variant(self) -> Any:
         """Convert this expression into a python object if possible."""
         return self.expr.to_variant()
 
+    @deprecated(since="41.0.0", message="Use :py:meth:`~Expr.schema_name` instead")
     def display_name(self) -> str:
         """Returns the name of this expression as it should appear in a schema.
 
         This name will not include any CAST expressions.
         """
-        return self.expr.display_name()
+        return self.schema_name()
+
+    def schema_name(self) -> str:
+        """Returns the name of this expression as it should appear in a schema.
+
+        This name will not include any CAST expressions.
+        """
+        return self.expr.schema_name()
 
     def canonical_name(self) -> str:
         """Returns a complete string representation of this expression."""
diff --git a/python/datafusion/tests/test_expr.py b/python/datafusion/tests/test_expr.py
index 056d2ea03..1aa93110c 100644
--- a/python/datafusion/tests/test_expr.py
+++ b/python/datafusion/tests/test_expr.py
@@ -192,3 +192,23 @@ def test_expr_getitem() -> None:
 
     assert names == ["Alice", "Bob", "Charlie", None]
     assert array_values == [2, 5, None, None]
+
+
+def test_display_name_deprecation():
+    import warnings
+    expr = col("foo")
+    with warnings.catch_warnings(record=True) as w:
+        # Cause all warnings to always be triggered
+        warnings.simplefilter("always")
+
+        # should trigger warning
+        name = expr.display_name()
+
+        # Verify some things
+        assert len(w) == 1
+        assert issubclass(w[-1].category, DeprecationWarning)
+        assert "deprecated" in str(w[-1].message)
+
+    # returns appropriate result
+    assert name == expr.schema_name()
+    assert name == "foo"
diff --git a/src/expr.rs b/src/expr.rs
index 4841b26b1..e1edbe864 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -189,7 +189,7 @@ impl PyExpr {
 
     /// Returns the name of this expression as it should appear in a schema. This name
     /// will not include any CAST expressions.
-    fn display_name(&self) -> PyResult<String> {
+    fn schema_name(&self) -> PyResult<String> {
         Ok(format!("{}", self.expr.schema_name()))
     }