Simplify invalid chemical symbol error message

Co-authored-by: Casper Welzel Andersen <43357585+CasperWA@users.noreply.github.com>
Materials-Consortia · Sep 23, 2021 · 97484de · 97484de
1 parent 49fa172
commit 97484de
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/optimade/models/structures.py b/optimade/models/structures.py
@@ -21,7 +21,7 @@
 )
 from optimade.server.warnings import MissingExpectedField
 
-EXTENDED_CHEMICAL_SYMBOLS = CHEMICAL_SYMBOLS + EXTRA_SYMBOLS
+EXTENDED_CHEMICAL_SYMBOLS = set(CHEMICAL_SYMBOLS + EXTRA_SYMBOLS)
 
 
 __all__ = (
@@ -146,7 +146,9 @@ class Species(BaseModel):
     @validator("chemical_symbols", each_item=True)
     def validate_chemical_symbols(cls, v):
         if not (v in EXTENDED_CHEMICAL_SYMBOLS):
-            raise ValueError(f"{v} MUST be in {EXTENDED_CHEMICAL_SYMBOLS}")
+            raise ValueError(
+                f'{v!r} MUST be an element symbol, e.g., "C", "He", or a special symbol from {EXTRA_SYMBOLS}.'
+            )
         return v
 
     @validator("concentration", "mass")