From 53255f1e3c018be910d521d0c89efd01d80dca35 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 23 Feb 2024 11:15:38 +0100
Subject: [PATCH 01/18] more informative error message for
 UnsetMetadataPassedError

---
 .../test_metaestimators_metadata_routing.py   |  2 +-
 sklearn/utils/_metadata_requests.py           | 73 +++++++++++++++----
 2 files changed, 59 insertions(+), 16 deletions(-)

diff --git a/sklearn/tests/test_metaestimators_metadata_routing.py b/sklearn/tests/test_metaestimators_metadata_routing.py
index 08a7e0ef9952a..9196d7a78c910 100644
--- a/sklearn/tests/test_metaestimators_metadata_routing.py
+++ b/sklearn/tests/test_metaestimators_metadata_routing.py
@@ -507,7 +507,7 @@ def test_error_on_missing_requests_for_sub_estimator(metaestimator):
             instance = cls(**kwargs)
             msg = (
                 f"[{key}] are passed but are not explicitly set as requested or not"
-                f" for {estimator.__class__.__name__}.{method_name}"
+                f" requested for {estimator.__class__.__name__}.{method_name}"
             )
             with pytest.raises(UnsetMetadataPassedError, match=re.escape(msg)):
                 method = getattr(instance, method_name)
diff --git a/sklearn/utils/_metadata_requests.py b/sklearn/utils/_metadata_requests.py
index 83cdf7790c7cd..ba1724bc62cc9 100644
--- a/sklearn/utils/_metadata_requests.py
+++ b/sklearn/utils/_metadata_requests.py
@@ -403,7 +403,7 @@ def _check_warnings(self, *, params):
                 "warning, or to True to consume and use the metadata."
             )
 
-    def _route_params(self, params):
+    def _route_params(self, params, parent, caller_method):
         """Prepare the given parameters to be passed to the method.
 
         The output of this method can be used directly as the input to the
@@ -414,6 +414,12 @@ def _route_params(self, params):
         params : dict
             A dictionary of provided metadata.
 
+        parent : object
+            Parent class object, that routes the metadata.
+
+        caller_method : str
+            Method from the parent class object, where the metadata is routed from.
+
         Returns
         -------
         params : Bunch
@@ -434,12 +440,20 @@ def _route_params(self, params):
             elif alias in args:
                 res[prop] = args[alias]
         if unrequested:
+            if self.method in COMPOSITE_METHODS:
+                callee_method = COMPOSITE_METHODS[self.method][0]
+            else:
+                callee_method = self.method
+            message = (
+                f"[{', '.join([key for key in unrequested])}] are passed but are"
+                " not explicitly set as requested or not requested for"
+                f" {self.owner}.{self.method}, which is used within"
+                f" {parent.__class__.__name__}.{caller_method}."
+                f" Call `{self.owner}.set_{callee_method}_request("
+                "{metadata}=True)` for each metadata."
+            )
             raise UnsetMetadataPassedError(
-                message=(
-                    f"[{', '.join([key for key in unrequested])}] are passed but are"
-                    " not explicitly set as requested or not for"
-                    f" {self.owner}.{self.method}"
-                ),
+                message=message,
                 unrequested_params=unrequested,
                 routed_params=res,
             )
@@ -591,7 +605,7 @@ def _get_param_names(self, method, return_alias, ignore_self_request=None):
         """
         return getattr(self, method)._get_param_names(return_alias=return_alias)
 
-    def _route_params(self, *, method, params):
+    def _route_params(self, *, method, caller_method, parent, params):
         """Prepare the given parameters to be passed to the method.
 
         The output of this method can be used directly as the input to the
@@ -603,6 +617,12 @@ def _route_params(self, *, method, params):
             The name of the method for which the parameters are requested and
             routed.
 
+        caller_method : str
+            Method from the parent class object, where the metadata is routed from.
+
+        parent : object
+            Parent class object, that routes the metadata.
+
         params : dict
             A dictionary of provided metadata.
 
@@ -612,7 +632,9 @@ def _route_params(self, *, method, params):
             A :class:`~sklearn.utils.Bunch` of {prop: value} which can be given to the
             corresponding method.
         """
-        return getattr(self, method)._route_params(params=params)
+        return getattr(self, method)._route_params(
+            params=params, parent=parent, caller_method=caller_method
+        )
 
     def _check_warnings(self, *, method, params):
         """Check whether metadata is passed which is marked as WARN.
@@ -938,7 +960,7 @@ def _get_param_names(self, *, method, return_alias, ignore_self_request):
                     )
         return res
 
-    def _route_params(self, *, params, method):
+    def _route_params(self, *, params, method, caller_method, parent):
         """Prepare the given parameters to be passed to the method.
 
         This is used when a router is used as a child object of another router.
@@ -950,12 +972,18 @@ def _route_params(self, *, params, method):
 
         Parameters
         ----------
+        params : dict
+            A dictionary of provided metadata.
+
         method : str
             The name of the method for which the parameters are requested and
             routed.
 
-        params : dict
-            A dictionary of provided metadata.
+        caller_method : str
+            Method from the parent class object, where the metadata is routed from.
+
+        parent : object
+            Parent class object, that routes the metadata.
 
         Returns
         -------
@@ -965,7 +993,14 @@ def _route_params(self, *, params, method):
         """
         res = Bunch()
         if self._self_request:
-            res.update(self._self_request._route_params(params=params, method=method))
+            res.update(
+                self._self_request._route_params(
+                    params=params,
+                    method=method,
+                    caller_method=caller_method,
+                    parent=parent,
+                )
+            )
 
         param_names = self._get_param_names(
             method=method, return_alias=True, ignore_self_request=True
@@ -987,7 +1022,7 @@ def _route_params(self, *, params, method):
         res.update(child_params)
         return res
 
-    def route_params(self, *, caller, params):
+    def route_params(self, *, caller, params, parent):
         """Return the input parameters requested by child objects.
 
         The output of this method is a bunch, which includes the inputs for all
@@ -1007,6 +1042,9 @@ def route_params(self, *, caller, params):
         params : dict
             A dictionary of provided metadata.
 
+        parent : object
+            Parent class object, that routes the metadata.
+
         Returns
         -------
         params : Bunch
@@ -1026,7 +1064,10 @@ def route_params(self, *, caller, params):
             for _callee, _caller in mapping:
                 if _caller == caller:
                     res[name][_callee] = router._route_params(
-                        params=params, method=_callee
+                        params=params,
+                        caller_method=caller,
+                        method=_callee,
+                        parent=parent,
                     )
         return res
 
@@ -1556,6 +1597,8 @@ def __getattr__(self, name):
 
     request_routing = get_routing_for_object(_obj)
     request_routing.validate_metadata(params=kwargs, method=_method)
-    routed_params = request_routing.route_params(params=kwargs, caller=_method)
+    routed_params = request_routing.route_params(
+        params=kwargs, caller=_method, parent=_obj
+    )
 
     return routed_params

From 693457933759100abcfb29b5995eb1491eeaa19b Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 23 Feb 2024 12:08:06 +0100
Subject: [PATCH 02/18] handle test errors

---
 sklearn/compose/tests/test_column_transformer.py | 2 +-
 sklearn/ensemble/tests/test_voting.py            | 2 +-
 sklearn/utils/_metadata_requests.py              | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/sklearn/compose/tests/test_column_transformer.py b/sklearn/compose/tests/test_column_transformer.py
index ec22ddf2f3ae0..56c4cd459aab5 100644
--- a/sklearn/compose/tests/test_column_transformer.py
+++ b/sklearn/compose/tests/test_column_transformer.py
@@ -2545,7 +2545,7 @@ def test_metadata_routing_error_for_column_transformer(method):
 
     error_message = (
         "[sample_weight, metadata] are passed but are not explicitly set as requested"
-        f" or not for ConsumingTransformer.{method}"
+        f" or not requested for ConsumingTransformer.{method}"
     )
     with pytest.raises(ValueError, match=re.escape(error_message)):
         if method == "transform":
diff --git a/sklearn/ensemble/tests/test_voting.py b/sklearn/ensemble/tests/test_voting.py
index 2f4c412bd6466..4b2c365752b72 100644
--- a/sklearn/ensemble/tests/test_voting.py
+++ b/sklearn/ensemble/tests/test_voting.py
@@ -777,7 +777,7 @@ def test_metadata_routing_error_for_voting_estimators(Estimator, Child):
 
     error_message = (
         "[sample_weight, metadata] are passed but are not explicitly set as requested"
-        f" or not for {Child.__name__}.fit"
+        f" or not requested for {Child.__name__}.fit"
     )
 
     with pytest.raises(ValueError, match=re.escape(error_message)):
diff --git a/sklearn/utils/_metadata_requests.py b/sklearn/utils/_metadata_requests.py
index ba1724bc62cc9..6274b84e6a969 100644
--- a/sklearn/utils/_metadata_requests.py
+++ b/sklearn/utils/_metadata_requests.py
@@ -1022,7 +1022,7 @@ def _route_params(self, *, params, method, caller_method, parent):
         res.update(child_params)
         return res
 
-    def route_params(self, *, caller, params, parent):
+    def route_params(self, *, caller, params, parent=None):
         """Return the input parameters requested by child objects.
 
         The output of this method is a bunch, which includes the inputs for all

From bef6606a56ab992d059c569e38278d16ed937e6c Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 23 Feb 2024 12:44:27 +0100
Subject: [PATCH 03/18] satisfied test

---
 sklearn/tests/test_pipeline.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sklearn/tests/test_pipeline.py b/sklearn/tests/test_pipeline.py
index 76ed9a7433d0f..f2aa73ebdce0e 100644
--- a/sklearn/tests/test_pipeline.py
+++ b/sklearn/tests/test_pipeline.py
@@ -1889,7 +1889,7 @@ def test_metadata_routing_error_for_pipeline(method):
     pipeline = Pipeline([("estimator", est)])
     error_message = (
         "[sample_weight, prop] are passed but are not explicitly set as requested"
-        f" or not for SimpleEstimator.{method}"
+        f" or not requested for SimpleEstimator.{method}"
     )
     with pytest.raises(ValueError, match=re.escape(error_message)):
         try:

From 7c567f78ac2a986fbdf630ca21bbf0ed860bb147 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 23 Feb 2024 13:21:45 +0100
Subject: [PATCH 04/18] handleing test errors

---
 doc/metadata_routing.rst               | 4 ++--
 sklearn/tests/test_metadata_routing.py | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/doc/metadata_routing.rst b/doc/metadata_routing.rst
index 4174f95e65ba0..109f82d197ff8 100644
--- a/doc/metadata_routing.rst
+++ b/doc/metadata_routing.rst
@@ -245,8 +245,8 @@ should be passed to the estimator's scorer or not::
     ...     ).fit(X, y, sample_weight=my_weights)
     ... except ValueError as e:
     ...     print(e)
-    [sample_weight] are passed but are not explicitly set as requested or not for
-    LogisticRegression.score
+    [sample_weight] are passed but are not explicitly set as requested or not
+    requested for LogisticRegression.score
 
 The issue can be fixed by explicitly setting the request value::
 
diff --git a/sklearn/tests/test_metadata_routing.py b/sklearn/tests/test_metadata_routing.py
index cf323d547e4d3..abe9f03610299 100644
--- a/sklearn/tests/test_metadata_routing.py
+++ b/sklearn/tests/test_metadata_routing.py
@@ -295,7 +295,7 @@ def test_simple_metadata_routing():
     clf = WeightedMetaClassifier(estimator=ConsumingClassifier())
     err_message = (
         "[sample_weight] are passed but are not explicitly set as requested or"
-        " not for ConsumingClassifier.fit"
+        " not requested for ConsumingClassifier.fit"
     )
     with pytest.raises(ValueError, match=re.escape(err_message)):
         clf.fit(X, y, sample_weight=my_weights)

From 497ec93af20592863aa08cdfdbf32561e4e2ade8 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 23 Feb 2024 14:16:54 +0100
Subject: [PATCH 05/18] disable routing like in #27357

---
 examples/miscellaneous/plot_metadata_routing.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/examples/miscellaneous/plot_metadata_routing.py b/examples/miscellaneous/plot_metadata_routing.py
index 9984bb6183348..d116b3544c73b 100644
--- a/examples/miscellaneous/plot_metadata_routing.py
+++ b/examples/miscellaneous/plot_metadata_routing.py
@@ -619,6 +619,11 @@ def predict(self, X):
 for w in record:
     print(w.message)
 
+# %%
+# In the end, we disable the configuration flag for metadata routing:
+
+set_config(enable_metadata_routing=False)
+
 # %%
 # Third Party Development and scikit-learn Dependency
 # ---------------------------------------------------

From fcb4325b516b432d12fc57e4c401762cfdc46026 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 23 Feb 2024 14:51:40 +0100
Subject: [PATCH 06/18] fix doctest failure

---
 doc/metadata_routing.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/doc/metadata_routing.rst b/doc/metadata_routing.rst
index 109f82d197ff8..bc9362de58014 100644
--- a/doc/metadata_routing.rst
+++ b/doc/metadata_routing.rst
@@ -246,7 +246,8 @@ should be passed to the estimator's scorer or not::
     ... except ValueError as e:
     ...     print(e)
     [sample_weight] are passed but are not explicitly set as requested or not
-    requested for LogisticRegression.score
+    requested for LogisticRegression.score, which is used within GridSearchCV.fit.
+    Call `LogisticRegression.set_score_request({metadata}=True)` for each metadata.
 
 The issue can be fixed by explicitly setting the request value::
 

From ea44b7e089995c377252eca5a721b95e6cb14ce2 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <91849487+StefanieSenger@users.noreply.github.com>
Date: Fri, 23 Feb 2024 16:36:29 +0100
Subject: [PATCH 07/18] Update doc/metadata_routing.rst

Co-authored-by: Adrin Jalali <adrin.jalali@gmail.com>
---
 doc/metadata_routing.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/metadata_routing.rst b/doc/metadata_routing.rst
index bc9362de58014..1533b1381aefd 100644
--- a/doc/metadata_routing.rst
+++ b/doc/metadata_routing.rst
@@ -247,7 +247,7 @@ should be passed to the estimator's scorer or not::
     ...     print(e)
     [sample_weight] are passed but are not explicitly set as requested or not
     requested for LogisticRegression.score, which is used within GridSearchCV.fit.
-    Call `LogisticRegression.set_score_request({metadata}=True)` for each metadata.
+    Call `LogisticRegression.set_score_request(sample_weight=True)` for each metadata.
 
 The issue can be fixed by explicitly setting the request value::
 

From 2c1e8d1aa416f16001cc44393e0f9320eee7e4fa Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 23 Feb 2024 17:09:04 +0100
Subject: [PATCH 08/18] added test

---
 doc/metadata_routing.rst               |  2 +-
 sklearn/tests/test_metadata_routing.py | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/doc/metadata_routing.rst b/doc/metadata_routing.rst
index 1533b1381aefd..bc9362de58014 100644
--- a/doc/metadata_routing.rst
+++ b/doc/metadata_routing.rst
@@ -247,7 +247,7 @@ should be passed to the estimator's scorer or not::
     ...     print(e)
     [sample_weight] are passed but are not explicitly set as requested or not
     requested for LogisticRegression.score, which is used within GridSearchCV.fit.
-    Call `LogisticRegression.set_score_request(sample_weight=True)` for each metadata.
+    Call `LogisticRegression.set_score_request({metadata}=True)` for each metadata.
 
 The issue can be fixed by explicitly setting the request value::
 
diff --git a/sklearn/tests/test_metadata_routing.py b/sklearn/tests/test_metadata_routing.py
index abe9f03610299..8323c95e4f1bc 100644
--- a/sklearn/tests/test_metadata_routing.py
+++ b/sklearn/tests/test_metadata_routing.py
@@ -15,7 +15,10 @@
     BaseEstimator,
     clone,
 )
+from sklearn.ensemble import VotingClassifier
+from sklearn.exceptions import UnsetMetadataPassedError
 from sklearn.linear_model import LinearRegression
+from sklearn.pipeline import Pipeline
 from sklearn.tests.metadata_routing_common import (
     ConsumingClassifier,
     ConsumingRegressor,
@@ -1029,3 +1032,18 @@ def fit(self, X, y, metadata=None):
         NotImplementedError, match="Estimator has not implemented metadata routing yet."
     ):
         MetaRegressor(estimator=Estimator()).fit(X, y, metadata=my_groups)
+
+
+def test_unsetmetadatapassederror_correct():
+    """Test that UnsetMetadataPassedError raises the correct error message when
+    set_{method}_request is not set in nested cases."""
+    voting = VotingClassifier(estimators=[("classifier", ConsumingClassifier())])
+    pipe = Pipeline([("voting", voting)])
+    msg = re.escape(
+        "[metadata] are passed but are not explicitly set as requested or not requested"
+        " for ConsumingClassifier.fit, which is used within VotingClassifier.fit. Call"
+        " `ConsumingClassifier.set_fit_request({metadata}=True)` for each metadata."
+    )
+
+    with pytest.raises(UnsetMetadataPassedError, match=msg):
+        pipe.fit(X, y, metadata="blah")

From 8ecb239f4f08b29686c7dbe795d28bdaf95334af Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 1 Mar 2024 14:11:00 +0100
Subject: [PATCH 09/18] changes after review

---
 sklearn/tests/test_metadata_routing.py | 19 +++++++-----
 sklearn/utils/_metadata_requests.py    | 43 +++++++++++++-------------
 2 files changed, 34 insertions(+), 28 deletions(-)

diff --git a/sklearn/tests/test_metadata_routing.py b/sklearn/tests/test_metadata_routing.py
index 8323c95e4f1bc..5431087c19d5f 100644
--- a/sklearn/tests/test_metadata_routing.py
+++ b/sklearn/tests/test_metadata_routing.py
@@ -15,10 +15,8 @@
     BaseEstimator,
     clone,
 )
-from sklearn.ensemble import VotingClassifier
 from sklearn.exceptions import UnsetMetadataPassedError
 from sklearn.linear_model import LinearRegression
-from sklearn.pipeline import Pipeline
 from sklearn.tests.metadata_routing_common import (
     ConsumingClassifier,
     ConsumingRegressor,
@@ -71,7 +69,13 @@ def enable_slep006():
 
 
 class SimplePipeline(BaseEstimator):
-    """A very simple pipeline, assuming the last step is always a predictor."""
+    """A very simple pipeline, assuming the last step is always a predictor.
+
+    Parameters
+    ----------
+    steps : iterable of objects
+        An iterable of transformers with the last step being a predictor.
+    """
 
     def __init__(self, steps):
         self.steps = steps
@@ -1037,12 +1041,13 @@ def fit(self, X, y, metadata=None):
 def test_unsetmetadatapassederror_correct():
     """Test that UnsetMetadataPassedError raises the correct error message when
     set_{method}_request is not set in nested cases."""
-    voting = VotingClassifier(estimators=[("classifier", ConsumingClassifier())])
-    pipe = Pipeline([("voting", voting)])
+    weighted_meta = WeightedMetaClassifier(estimator=ConsumingClassifier())
+    pipe = SimplePipeline([weighted_meta])
     msg = re.escape(
         "[metadata] are passed but are not explicitly set as requested or not requested"
-        " for ConsumingClassifier.fit, which is used within VotingClassifier.fit. Call"
-        " `ConsumingClassifier.set_fit_request({metadata}=True)` for each metadata."
+        " for ConsumingClassifier.fit, which is used within WeightedMetaClassifier.fit."
+        " Call `ConsumingClassifier.set_fit_request({metadata}=True/False)` for each"
+        " metadata you want to request/ignore."
     )
 
     with pytest.raises(UnsetMetadataPassedError, match=msg):
diff --git a/sklearn/utils/_metadata_requests.py b/sklearn/utils/_metadata_requests.py
index 6274b84e6a969..2ff9a8c3449ae 100644
--- a/sklearn/utils/_metadata_requests.py
+++ b/sklearn/utils/_metadata_requests.py
@@ -403,7 +403,7 @@ def _check_warnings(self, *, params):
                 "warning, or to True to consume and use the metadata."
             )
 
-    def _route_params(self, params, parent, caller_method):
+    def _route_params(self, params, parent, caller):
         """Prepare the given parameters to be passed to the method.
 
         The output of this method can be used directly as the input to the
@@ -417,7 +417,7 @@ def _route_params(self, params, parent, caller_method):
         parent : object
             Parent class object, that routes the metadata.
 
-        caller_method : str
+        caller : str
             Method from the parent class object, where the metadata is routed from.
 
         Returns
@@ -445,12 +445,12 @@ def _route_params(self, params, parent, caller_method):
             else:
                 callee_method = self.method
             message = (
-                f"[{', '.join([key for key in unrequested])}] are passed but are"
-                " not explicitly set as requested or not requested for"
+                f"[{', '.join([key for key in unrequested])}] are passed but are not"
+                " explicitly set as requested or not requested for"
                 f" {self.owner}.{self.method}, which is used within"
-                f" {parent.__class__.__name__}.{caller_method}."
-                f" Call `{self.owner}.set_{callee_method}_request("
-                "{metadata}=True)` for each metadata."
+                f" {parent.__class__.__name__}.{caller}. Call"
+                f" `{self.owner}.set_{callee_method}_request({{metadata}}=True/False)`"
+                " for each metadata you want to request/ignore."
             )
             raise UnsetMetadataPassedError(
                 message=message,
@@ -605,7 +605,7 @@ def _get_param_names(self, method, return_alias, ignore_self_request=None):
         """
         return getattr(self, method)._get_param_names(return_alias=return_alias)
 
-    def _route_params(self, *, method, caller_method, parent, params):
+    def _route_params(self, *, method, parent, caller, params):
         """Prepare the given parameters to be passed to the method.
 
         The output of this method can be used directly as the input to the
@@ -617,12 +617,12 @@ def _route_params(self, *, method, caller_method, parent, params):
             The name of the method for which the parameters are requested and
             routed.
 
-        caller_method : str
-            Method from the parent class object, where the metadata is routed from.
-
         parent : object
             Parent class object, that routes the metadata.
 
+        caller : str
+            Method from the parent class object, where the metadata is routed from.
+
         params : dict
             A dictionary of provided metadata.
 
@@ -633,7 +633,7 @@ def _route_params(self, *, method, caller_method, parent, params):
             corresponding method.
         """
         return getattr(self, method)._route_params(
-            params=params, parent=parent, caller_method=caller_method
+            params=params, parent=parent, caller=caller
         )
 
     def _check_warnings(self, *, method, params):
@@ -960,7 +960,7 @@ def _get_param_names(self, *, method, return_alias, ignore_self_request):
                     )
         return res
 
-    def _route_params(self, *, params, method, caller_method, parent):
+    def _route_params(self, *, params, method, parent, caller):
         """Prepare the given parameters to be passed to the method.
 
         This is used when a router is used as a child object of another router.
@@ -979,12 +979,12 @@ def _route_params(self, *, params, method, caller_method, parent):
             The name of the method for which the parameters are requested and
             routed.
 
-        caller_method : str
-            Method from the parent class object, where the metadata is routed from.
-
         parent : object
             Parent class object, that routes the metadata.
 
+        caller : str
+            Method from the parent class object, where the metadata is routed from.
+
         Returns
         -------
         params : Bunch
@@ -996,9 +996,9 @@ def _route_params(self, *, params, method, caller_method, parent):
             res.update(
                 self._self_request._route_params(
                     params=params,
-                    method=method,
-                    caller_method=caller_method,
                     parent=parent,
+                    caller=caller,
+                    method=method,
                 )
             )
 
@@ -1022,7 +1022,8 @@ def _route_params(self, *, params, method, caller_method, parent):
         res.update(child_params)
         return res
 
-    def route_params(self, *, caller, params, parent=None):
+    # def route_params(self, *, caller, params, parent=None):
+    def route_params(self, *, caller, params, parent):
         """Return the input parameters requested by child objects.
 
         The output of this method is a bunch, which includes the inputs for all
@@ -1065,9 +1066,9 @@ def route_params(self, *, caller, params, parent=None):
                 if _caller == caller:
                     res[name][_callee] = router._route_params(
                         params=params,
-                        caller_method=caller,
-                        method=_callee,
                         parent=parent,
+                        caller=caller,
+                        method=_callee,
                     )
         return res
 

From 2073a270b1910517645626c7f72085aa375d990b Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 1 Mar 2024 16:15:10 +0100
Subject: [PATCH 10/18] correct error message for composite methods

---
 sklearn/tests/test_metadata_routing.py | 19 +++++++++++++++++++
 sklearn/utils/_metadata_requests.py    | 16 +++++++++++-----
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/sklearn/tests/test_metadata_routing.py b/sklearn/tests/test_metadata_routing.py
index 5431087c19d5f..9e8ee47c35782 100644
--- a/sklearn/tests/test_metadata_routing.py
+++ b/sklearn/tests/test_metadata_routing.py
@@ -17,6 +17,7 @@
 )
 from sklearn.exceptions import UnsetMetadataPassedError
 from sklearn.linear_model import LinearRegression
+from sklearn.pipeline import Pipeline
 from sklearn.tests.metadata_routing_common import (
     ConsumingClassifier,
     ConsumingRegressor,
@@ -1052,3 +1053,21 @@ def test_unsetmetadatapassederror_correct():
 
     with pytest.raises(UnsetMetadataPassedError, match=msg):
         pipe.fit(X, y, metadata="blah")
+
+
+def test_unsetmetadatapassederror_correct_for_composite_methods():
+    """Test that UnsetMetadataPassedError raises the correct error message when
+    composite metadata request methods are not set in nested cases."""
+    consuming_transformer = ConsumingTransformer()
+    pipe = Pipeline([("consuming_transformer", consuming_transformer)])
+
+    msg = re.escape(
+        "[metadata] are passed but are not explicitly set as requested or not requested"
+        " for ConsumingTransformer.fit_transform, which is used within"
+        " Pipeline.fit_transform. Call"
+        " `ConsumingTransformer.set_fit_request({metadata}=True/False)"
+        ".set_transform_request({metadata}=True/False)`"
+        " for each metadata you want to request/ignore."
+    )
+    with pytest.raises(UnsetMetadataPassedError, match=msg):
+        pipe.fit_transform(X, y, metadata="blah")
diff --git a/sklearn/utils/_metadata_requests.py b/sklearn/utils/_metadata_requests.py
index 2ff9a8c3449ae..cf80df91a58e5 100644
--- a/sklearn/utils/_metadata_requests.py
+++ b/sklearn/utils/_metadata_requests.py
@@ -441,16 +441,22 @@ def _route_params(self, params, parent, caller):
                 res[prop] = args[alias]
         if unrequested:
             if self.method in COMPOSITE_METHODS:
-                callee_method = COMPOSITE_METHODS[self.method][0]
+                callee_methods = list(COMPOSITE_METHODS[self.method])
             else:
-                callee_method = self.method
+                callee_methods = [self.method]
+            set_requests_on = "".join(
+                [
+                    f".set_{method}_request({{metadata}}=True/False)"
+                    for method in callee_methods
+                ]
+            )
             message = (
                 f"[{', '.join([key for key in unrequested])}] are passed but are not"
                 " explicitly set as requested or not requested for"
                 f" {self.owner}.{self.method}, which is used within"
-                f" {parent.__class__.__name__}.{caller}. Call"
-                f" `{self.owner}.set_{callee_method}_request({{metadata}}=True/False)`"
-                " for each metadata you want to request/ignore."
+                f" {parent.__class__.__name__}.{caller}. Call `{self.owner}"
+                + set_requests_on
+                + "` for each metadata you want to request/ignore."
             )
             raise UnsetMetadataPassedError(
                 message=message,

From 0ea9e4d35da45b9325411eb7193e61e26467e662 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 1 Mar 2024 17:17:20 +0100
Subject: [PATCH 11/18] adjust for parent param without default value

---
 examples/miscellaneous/plot_metadata_routing.py | 14 ++++++++++----
 sklearn/metrics/tests/test_score_objects.py     |  8 ++++++--
 sklearn/utils/_metadata_requests.py             |  5 +++--
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/examples/miscellaneous/plot_metadata_routing.py b/examples/miscellaneous/plot_metadata_routing.py
index d116b3544c73b..bc82db7acca7f 100644
--- a/examples/miscellaneous/plot_metadata_routing.py
+++ b/examples/miscellaneous/plot_metadata_routing.py
@@ -169,7 +169,9 @@ def fit(self, X, y, **fit_params):
         # we can use provided utility methods to map the given metadata to what
         # is required by the underlying estimator. Here `method` refers to the
         # parent's method, i.e. `fit` in this example.
-        routed_params = request_router.route_params(params=fit_params, caller="fit")
+        routed_params = request_router.route_params(
+            params=fit_params, caller="fit", parent=self.__class__
+        )
 
         # the output has a key for each object's method which is used here,
         # i.e. parent's `fit` method, containing the metadata which should be
@@ -186,7 +188,7 @@ def predict(self, X, **predict_params):
         request_router.validate_metadata(params=predict_params, method="predict")
         # and then prepare the input to the underlying `predict` method.
         routed_params = request_router.route_params(
-            params=predict_params, caller="predict"
+            params=predict_params, caller="predict", parent=self.__class__
         )
         return self.estimator_.predict(X, **routed_params.estimator.predict)
 
@@ -342,7 +344,9 @@ def fit(self, X, y, sample_weight, **fit_params):
         request_router.validate_metadata(params=fit_params, method="fit")
         # we can use provided utility methods to map the given metadata to what
         # is required by the underlying estimator
-        params = request_router.route_params(params=fit_params, caller="fit")
+        params = request_router.route_params(
+            params=fit_params, caller="fit", parent=self.__class__
+        )
         self.estimator_ = clone(self.estimator).fit(X, y, **params.estimator.fit)
         self.classes_ = self.estimator_.classes_
         return self
@@ -353,7 +357,9 @@ def predict(self, X, **predict_params):
         request_router = get_routing_for_object(self)
         request_router.validate_metadata(params=predict_params, method="predict")
         # and then prepare the input to the underlying ``predict`` method.
-        params = request_router.route_params(params=predict_params, caller="predict")
+        params = request_router.route_params(
+            params=predict_params, caller="predict", parent=self.__class__
+        )
         return self.estimator_.predict(X, **params.estimator.predict)
 
 
diff --git a/sklearn/metrics/tests/test_score_objects.py b/sklearn/metrics/tests/test_score_objects.py
index c721922f1b2d5..0f52becc9c70e 100644
--- a/sklearn/metrics/tests/test_score_objects.py
+++ b/sklearn/metrics/tests/test_score_objects.py
@@ -1239,7 +1239,9 @@ def test_scorer_metadata_request(name):
     with pytest.raises(TypeError, match="got unexpected argument"):
         router.validate_metadata(params={"sample_weight": 1}, method="score")
     # make sure `sample_weight` is not routed even if passed.
-    routed_params = router.route_params(params={"sample_weight": 1}, caller="score")
+    routed_params = router.route_params(
+        params={"sample_weight": 1}, caller="score", parent=name
+    )
     assert not routed_params.scorer.score
 
     # make sure putting weighted_scorer in a router requests sample_weight
@@ -1247,7 +1249,9 @@ def test_scorer_metadata_request(name):
         scorer=weighted_scorer, method_mapping="score"
     )
     router.validate_metadata(params={"sample_weight": 1}, method="score")
-    routed_params = router.route_params(params={"sample_weight": 1}, caller="score")
+    routed_params = router.route_params(
+        params={"sample_weight": 1}, caller="score", parent=name
+    )
     assert list(routed_params.scorer.score.keys()) == ["sample_weight"]
 
 
diff --git a/sklearn/utils/_metadata_requests.py b/sklearn/utils/_metadata_requests.py
index cf80df91a58e5..66a99c7a03b6f 100644
--- a/sklearn/utils/_metadata_requests.py
+++ b/sklearn/utils/_metadata_requests.py
@@ -440,6 +440,8 @@ def _route_params(self, params, parent, caller):
             elif alias in args:
                 res[prop] = args[alias]
         if unrequested:
+            if parent.__class__.__name__ != "str":
+                parent = parent.__class__.__name__
             if self.method in COMPOSITE_METHODS:
                 callee_methods = list(COMPOSITE_METHODS[self.method])
             else:
@@ -454,7 +456,7 @@ def _route_params(self, params, parent, caller):
                 f"[{', '.join([key for key in unrequested])}] are passed but are not"
                 " explicitly set as requested or not requested for"
                 f" {self.owner}.{self.method}, which is used within"
-                f" {parent.__class__.__name__}.{caller}. Call `{self.owner}"
+                f" {parent}.{caller}. Call `{self.owner}"
                 + set_requests_on
                 + "` for each metadata you want to request/ignore."
             )
@@ -1028,7 +1030,6 @@ def _route_params(self, *, params, method, parent, caller):
         res.update(child_params)
         return res
 
-    # def route_params(self, *, caller, params, parent=None):
     def route_params(self, *, caller, params, parent):
         """Return the input parameters requested by child objects.
 

From 5f7d734381f76b26690fd668a46eacb8ef83de04 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Tue, 5 Mar 2024 09:17:50 +0100
Subject: [PATCH 12/18] fix expected error message

---
 doc/metadata_routing.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/doc/metadata_routing.rst b/doc/metadata_routing.rst
index dbc4a5d147118..f171d6c0b6317 100644
--- a/doc/metadata_routing.rst
+++ b/doc/metadata_routing.rst
@@ -247,7 +247,8 @@ should be passed to the estimator's scorer or not::
     ...     print(e)
     [sample_weight] are passed but are not explicitly set as requested or not
     requested for LogisticRegression.score, which is used within GridSearchCV.fit.
-    Call `LogisticRegression.set_score_request({metadata}=True)` for each metadata.
+    Call `LogisticRegression.set_score_request({metadata}=True/False)` for each metadata
+    you want to request/ignore.
 
 The issue can be fixed by explicitly setting the request value::
 

From f7bff85cb54804127e0ad97d257b9f4ded8ed72a Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Tue, 5 Mar 2024 13:06:23 +0100
Subject: [PATCH 13/18] clearer error message for TypeError in
 validate_metadata

---
 sklearn/utils/_metadata_requests.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sklearn/utils/_metadata_requests.py b/sklearn/utils/_metadata_requests.py
index 7775d25c8a4ac..e8b0bc4605654 100644
--- a/sklearn/utils/_metadata_requests.py
+++ b/sklearn/utils/_metadata_requests.py
@@ -1108,7 +1108,7 @@ def validate_metadata(self, *, method, params):
         if extra_keys:
             raise TypeError(
                 f"{self.owner}.{method} got unexpected argument(s) {extra_keys}, which"
-                " are not requested metadata in any object."
+                " are not routed to any object."
             )
 
     def _serialize(self):

From 24483d2eec034012defbf7599905adfc26b24d76 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Thu, 7 Mar 2024 15:39:53 +0100
Subject: [PATCH 14/18] removed wrapping in list

---
 sklearn/utils/_metadata_requests.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sklearn/utils/_metadata_requests.py b/sklearn/utils/_metadata_requests.py
index e8b0bc4605654..2cd4833192d4d 100644
--- a/sklearn/utils/_metadata_requests.py
+++ b/sklearn/utils/_metadata_requests.py
@@ -440,10 +440,12 @@ def _route_params(self, params, parent, caller):
             elif alias in args:
                 res[prop] = args[alias]
         if unrequested:
+            # we want to get the parent's class name, except for cases, when the router
+            # is a function
             if parent.__class__.__name__ != "str":
                 parent = parent.__class__.__name__
             if self.method in COMPOSITE_METHODS:
-                callee_methods = list(COMPOSITE_METHODS[self.method])
+                callee_methods = COMPOSITE_METHODS[self.method]
             else:
                 callee_methods = [self.method]
             set_requests_on = "".join(

From cfec1003daa968ba94f94e592230dc09bd87c3a2 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Tue, 12 Mar 2024 16:26:58 +0100
Subject: [PATCH 15/18] move parent param one function down, get string
 directly by MetadataRouter.owner

---
 examples/miscellaneous/plot_metadata_routing.py | 14 ++++----------
 sklearn/metrics/tests/test_score_objects.py     |  8 ++------
 sklearn/utils/_metadata_requests.py             | 15 +++------------
 3 files changed, 9 insertions(+), 28 deletions(-)

diff --git a/examples/miscellaneous/plot_metadata_routing.py b/examples/miscellaneous/plot_metadata_routing.py
index bc82db7acca7f..d116b3544c73b 100644
--- a/examples/miscellaneous/plot_metadata_routing.py
+++ b/examples/miscellaneous/plot_metadata_routing.py
@@ -169,9 +169,7 @@ def fit(self, X, y, **fit_params):
         # we can use provided utility methods to map the given metadata to what
         # is required by the underlying estimator. Here `method` refers to the
         # parent's method, i.e. `fit` in this example.
-        routed_params = request_router.route_params(
-            params=fit_params, caller="fit", parent=self.__class__
-        )
+        routed_params = request_router.route_params(params=fit_params, caller="fit")
 
         # the output has a key for each object's method which is used here,
         # i.e. parent's `fit` method, containing the metadata which should be
@@ -188,7 +186,7 @@ def predict(self, X, **predict_params):
         request_router.validate_metadata(params=predict_params, method="predict")
         # and then prepare the input to the underlying `predict` method.
         routed_params = request_router.route_params(
-            params=predict_params, caller="predict", parent=self.__class__
+            params=predict_params, caller="predict"
         )
         return self.estimator_.predict(X, **routed_params.estimator.predict)
 
@@ -344,9 +342,7 @@ def fit(self, X, y, sample_weight, **fit_params):
         request_router.validate_metadata(params=fit_params, method="fit")
         # we can use provided utility methods to map the given metadata to what
         # is required by the underlying estimator
-        params = request_router.route_params(
-            params=fit_params, caller="fit", parent=self.__class__
-        )
+        params = request_router.route_params(params=fit_params, caller="fit")
         self.estimator_ = clone(self.estimator).fit(X, y, **params.estimator.fit)
         self.classes_ = self.estimator_.classes_
         return self
@@ -357,9 +353,7 @@ def predict(self, X, **predict_params):
         request_router = get_routing_for_object(self)
         request_router.validate_metadata(params=predict_params, method="predict")
         # and then prepare the input to the underlying ``predict`` method.
-        params = request_router.route_params(
-            params=predict_params, caller="predict", parent=self.__class__
-        )
+        params = request_router.route_params(params=predict_params, caller="predict")
         return self.estimator_.predict(X, **params.estimator.predict)
 
 
diff --git a/sklearn/metrics/tests/test_score_objects.py b/sklearn/metrics/tests/test_score_objects.py
index 0f52becc9c70e..c721922f1b2d5 100644
--- a/sklearn/metrics/tests/test_score_objects.py
+++ b/sklearn/metrics/tests/test_score_objects.py
@@ -1239,9 +1239,7 @@ def test_scorer_metadata_request(name):
     with pytest.raises(TypeError, match="got unexpected argument"):
         router.validate_metadata(params={"sample_weight": 1}, method="score")
     # make sure `sample_weight` is not routed even if passed.
-    routed_params = router.route_params(
-        params={"sample_weight": 1}, caller="score", parent=name
-    )
+    routed_params = router.route_params(params={"sample_weight": 1}, caller="score")
     assert not routed_params.scorer.score
 
     # make sure putting weighted_scorer in a router requests sample_weight
@@ -1249,9 +1247,7 @@ def test_scorer_metadata_request(name):
         scorer=weighted_scorer, method_mapping="score"
     )
     router.validate_metadata(params={"sample_weight": 1}, method="score")
-    routed_params = router.route_params(
-        params={"sample_weight": 1}, caller="score", parent=name
-    )
+    routed_params = router.route_params(params={"sample_weight": 1}, caller="score")
     assert list(routed_params.scorer.score.keys()) == ["sample_weight"]
 
 
diff --git a/sklearn/utils/_metadata_requests.py b/sklearn/utils/_metadata_requests.py
index 2cd4833192d4d..c83d040955d76 100644
--- a/sklearn/utils/_metadata_requests.py
+++ b/sklearn/utils/_metadata_requests.py
@@ -440,10 +440,6 @@ def _route_params(self, params, parent, caller):
             elif alias in args:
                 res[prop] = args[alias]
         if unrequested:
-            # we want to get the parent's class name, except for cases, when the router
-            # is a function
-            if parent.__class__.__name__ != "str":
-                parent = parent.__class__.__name__
             if self.method in COMPOSITE_METHODS:
                 callee_methods = COMPOSITE_METHODS[self.method]
             else:
@@ -1032,7 +1028,7 @@ def _route_params(self, *, params, method, parent, caller):
         res.update(child_params)
         return res
 
-    def route_params(self, *, caller, params, parent):
+    def route_params(self, *, caller, params):
         """Return the input parameters requested by child objects.
 
         The output of this method is a bunch, which includes the inputs for all
@@ -1052,9 +1048,6 @@ def route_params(self, *, caller, params, parent):
         params : dict
             A dictionary of provided metadata.
 
-        parent : object
-            Parent class object, that routes the metadata.
-
         Returns
         -------
         params : Bunch
@@ -1075,7 +1068,7 @@ def route_params(self, *, caller, params, parent):
                 if _caller == caller:
                     res[name][_callee] = router._route_params(
                         params=params,
-                        parent=parent,
+                        parent=self.owner,
                         caller=caller,
                         method=_callee,
                     )
@@ -1607,8 +1600,6 @@ def __getattr__(self, name):
 
     request_routing = get_routing_for_object(_obj)
     request_routing.validate_metadata(params=kwargs, method=_method)
-    routed_params = request_routing.route_params(
-        params=kwargs, caller=_method, parent=_obj
-    )
+    routed_params = request_routing.route_params(params=kwargs, caller=_method)
 
     return routed_params

From e0eef01987437f6ad4aa9e2c837b75266771d8f6 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Tue, 12 Mar 2024 16:53:51 +0100
Subject: [PATCH 16/18] same signature for methods with same name

---
 sklearn/utils/_metadata_requests.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/sklearn/utils/_metadata_requests.py b/sklearn/utils/_metadata_requests.py
index c83d040955d76..9e067fa29195b 100644
--- a/sklearn/utils/_metadata_requests.py
+++ b/sklearn/utils/_metadata_requests.py
@@ -611,7 +611,7 @@ def _get_param_names(self, method, return_alias, ignore_self_request=None):
         """
         return getattr(self, method)._get_param_names(return_alias=return_alias)
 
-    def _route_params(self, *, method, parent, caller, params):
+    def _route_params(self, *, params, method, parent, caller):
         """Prepare the given parameters to be passed to the method.
 
         The output of this method can be used directly as the input to the
@@ -619,6 +619,9 @@ def _route_params(self, *, method, parent, caller, params):
 
         Parameters
         ----------
+        params : dict
+            A dictionary of provided metadata.
+
         method : str
             The name of the method for which the parameters are requested and
             routed.
@@ -629,9 +632,6 @@ def _route_params(self, *, method, parent, caller, params):
         caller : str
             Method from the parent class object, where the metadata is routed from.
 
-        params : dict
-            A dictionary of provided metadata.
-
         Returns
         -------
         params : Bunch
@@ -1002,9 +1002,9 @@ def _route_params(self, *, params, method, parent, caller):
             res.update(
                 self._self_request._route_params(
                     params=params,
+                    method=method,
                     parent=parent,
                     caller=caller,
-                    method=method,
                 )
             )
 
@@ -1068,9 +1068,9 @@ def route_params(self, *, caller, params):
                 if _caller == caller:
                     res[name][_callee] = router._route_params(
                         params=params,
+                        method=_callee,
                         parent=self.owner,
                         caller=caller,
-                        method=_callee,
                     )
         return res
 

From f7614e2f872ebf835947bfaf4fcb0127ed7176ed Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Fri, 15 Mar 2024 15:28:08 +0100
Subject: [PATCH 17/18] fix test

---
 sklearn/tests/test_pipeline.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sklearn/tests/test_pipeline.py b/sklearn/tests/test_pipeline.py
index a5a5de41cb943..55f520de7c62e 100644
--- a/sklearn/tests/test_pipeline.py
+++ b/sklearn/tests/test_pipeline.py
@@ -1975,7 +1975,7 @@ def test_feature_union_metadata_routing_error():
 
     error_message = (
         "[sample_weight, metadata] are passed but are not explicitly set as requested"
-        f" or not for {ConsumingTransformer.__name__}.fit"
+        f" or not requested for {ConsumingTransformer.__name__}.fit"
     )
 
     with pytest.raises(UnsetMetadataPassedError, match=re.escape(error_message)):
@@ -1995,7 +1995,7 @@ def test_feature_union_metadata_routing_error():
 
     error_message = (
         "[sample_weight, metadata] are passed but are not explicitly set as requested "
-        f"or not for {ConsumingTransformer.__name__}.transform"
+        f"or not requested for {ConsumingTransformer.__name__}.transform"
     )
 
     with pytest.raises(UnsetMetadataPassedError, match=re.escape(error_message)):

From 96e42a05a572d08521ae5247fe8ae0c1fa0b36f6 Mon Sep 17 00:00:00 2001
From: Stefanie Senger <stefanie.senger@posteo.de>
Date: Mon, 8 Apr 2024 13:18:44 +0200
Subject: [PATCH 18/18] satisfy linting

---
 sklearn/tests/test_metadata_routing.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sklearn/tests/test_metadata_routing.py b/sklearn/tests/test_metadata_routing.py
index e094701dc266e..110452870d682 100644
--- a/sklearn/tests/test_metadata_routing.py
+++ b/sklearn/tests/test_metadata_routing.py
@@ -1074,6 +1074,7 @@ def test_unsetmetadatapassederror_correct_for_composite_methods():
     with pytest.raises(UnsetMetadataPassedError, match=msg):
         pipe.fit_transform(X, y, metadata="blah")
 
+
 def test_unbound_set_methods_work():
     """Tests that if the set_{method}_request is unbound, it still works.