Reintroduce grid_model key for backwards compatibility

src/fmu/dataio/dataio.py

@@ -312,6 +312,8 @@ class ExportData:
             Use with care and avoid if possible! (*) For absolute paths, the class
             variable allow_forcefolder_absolute must set to True.
 
+        grid_model: Currently allowed but planned for deprecation
+
         include_index: This applies to Pandas (table) data only, and if True then the
             index column will be exported. Deprecated, use class variable
             ``table_include_index`` instead
@@ -437,6 +439,7 @@ class ExportData:
     description: Union[str, list] = ""
     fmu_context: str = "realization"
     forcefolder: str = ""
+    grid_model: Optional[str] = None
     is_observation: bool = False
     is_prediction: bool = True
     name: str = ""
@@ -503,12 +506,19 @@ def __post_init__(self):
         logger.info("Ran __post_init__")
 
     def _show_deprecations_or_notimplemented(self):
-        """Warn on deprecated keys og on stuff not implemented yet."""
+        """Warn on deprecated keys or on stuff not implemented yet."""
 
         if self.runpath:
             warn(
                 "The 'runpath' key has currently no function. It will be evaluated for "
-                "removal in fmu-dataio version 1. Use 'casepath' instead!",
+                "removal in fmu-dataio version 2. Use 'casepath' instead!",
+                PendingDeprecationWarning,
+            )
+
+        if self.grid_model:
+            warn(
+                "The 'grid_model' key has currently no function. It will be evaluated "
+                "for removal in fmu-dataio version 2.",
                 PendingDeprecationWarning,
             )
 

tests/test_units/test_dataio.py

@@ -55,6 +55,12 @@ def test_update_check_settings_shall_fail(globalconfig1):
             PendingDeprecationWarning,
             r"The 'runpath' key has currently no function",
         ),
+        (
+            "grid_model",
+            "some",
+            PendingDeprecationWarning,
+            r"The 'grid_model' key has currently no function",
+        ),
     ],
 )
 def test_deprecated_keys(globalconfig1, regsurf, key, value, wtype, expected_msg):