add get_first_provenance and error handling for #1268

src/esm_parser/provenance.py

@@ -523,6 +523,23 @@ def get_provenance(self, index=-1):
 
         return provenance_dict
 
+    def get_first_provenance(self):
+        """
+        Recursively loops through the dictionary keys and returns the first provenance
+        found in the nested values.
+
+        Returns
+        -------
+        first_provenance : esm_parser.provenance.Provenance
+            The first provenance found in the nested values
+        """
+        first_provenance = None
+        for key, val in self.items():
+            if isinstance(val, PROVENANCE_MAPPINGS):
+                return val.get_first_provenance()
+            elif hasattr(val, "provenance"):
+                return val.provenance[-1]
+
     def __setitem__(self, key, val):
         """
         Any time an item in a DictWithProvenance is set, extend the old provenance of
@@ -773,6 +790,23 @@ def get_provenance(self, index=-1):
 
         return provenance_list
 
+    def get_first_provenance(self):
+        """
+        Recursively loops through the list elements and returns the first provenance
+        found in the nested values.
+
+        Returns
+        -------
+        first_provenance : esm_parser.provenance.Provenance
+            The first provenance found in the nested values
+        """
+        first_provenance = None
+        for elem in self:
+            if isinstance(elem, PROVENANCE_MAPPINGS):
+                return elem.get_first_provenance()
+            elif hasattr(elem, "provenance"):
+                return elem.provenance[-1]
+
     def __setitem__(self, indx, val):
         """
         Any time an item in a ListWithProvenance is set, extend the old provenance of

src/esm_runscripts/coupler.py

@@ -159,14 +159,29 @@ def add_files(self, full_config):
                             sys.exit(0)
 
                     direction_info = None
-                    if "coupling_directions" in full_config[self.name]:
-                        if (
-                            right_grid + "->" + left_grid
-                            in full_config[self.name]["coupling_directions"]
-                        ):
-                            direction_info = full_config[self.name][
-                                "coupling_directions"
-                            ][right_grid + "->" + left_grid]
+                    coupling_directions = full_config[self.name].get(
+                        "coupling_directions"
+                    )
+                    if coupling_directions:
+                        direction = f"{right_grid}->{left_grid}"
+                        direction_info = coupling_directions.get(direction)
+                        if not direction_info:
+                            first_provenance = (
+                                coupling_directions.get_first_provenance()
+                            )
+                            location_hint = ""
+                            if first_provenance:
+                                yaml_file = first_provenance.get("yaml_file")
+                                line = first_provenance.get("line")
+                                location_hint = (
+                                    f" (for example near ``{yaml_file},line:{line}``)"
+                                )
+                            esm_parser.user_error(
+                                "Missing coupling direction",
+                                f"The ``{direction}`` does not exist in "
+                                f"``{self.name}.coupling_directions``. You can solve "
+                                f"this by defining it there{location_hint}."
+                            )
                     transf_info = None
                     if "coupling_methods" in full_config[self.name]:
                         if interpolation in full_config[self.name]["coupling_methods"]: