Merge pull request #4672 from pybamm-team/fix-incorrect-error-msg

src/pybamm/util.py

@@ -94,10 +94,16 @@ def __getitem__(self, key):
                 ) from error
             best_matches = self.get_best_matches(key)
             for k in best_matches:
-                if key in k and k.endswith("]"):
+                if key in k and k.endswith("]") and not key.endswith("]"):
                     raise KeyError(
                         f"'{key}' not found. Use the dimensional version '{k}' instead."
                     ) from error
+                elif key in k and (
+                    k.startswith("Primary") or k.startswith("Secondary")
+                ):
+                    raise KeyError(
+                        f"'{key}' not found. If you are using a composite model, you may need to use {k} instead. Otherwise, best matches are {best_matches}"
+                    ) from error
             raise KeyError(
                 f"'{key}' not found. Best matches are {best_matches}"
             ) from error

tests/unit/test_util.py

@@ -35,6 +35,7 @@ def test_fuzzy_dict(self):
                 "Lithium plating current": 4,
                 "A dimensional variable [m]": 5,
                 "Positive particle diffusivity [m2.s-1]": 6,
+                "Primary: Open circuit voltage [V]": 7,
             }
         )
         d2 = pybamm.FuzzyDict(
@@ -52,6 +53,9 @@ def test_fuzzy_dict(self):
         with pytest.raises(KeyError, match="dimensional version"):
             d.__getitem__("A dimensional variable")
 
+        with pytest.raises(KeyError, match="composite model"):
+            d.__getitem__("Open circuit voltage [V]")
+
         with pytest.raises(KeyError, match="open circuit voltage"):
             d.__getitem__("Measured open circuit voltage [V]")