Fix #599 by updating error message

- No longer use length of dummy value
- Apply concentration validator before chemical_symbols which may be
  invalid

optimade/models/structures.py

@@ -138,11 +138,12 @@ def validate_chemical_symbols(cls, v):
             raise ValueError(f"{v} MUST be in {EXTENDED_CHEMICAL_SYMBOLS}")
         return v
 
-    @validator("concentration")
+    @validator("concentration", pre=True)
     def validate_concentration(cls, v, values):
         if len(v) != len(values.get("chemical_symbols", [])):
             raise ValueError(
-                f"Length of concentration ({len(v)}) MUST equal length of chemical_symbols ({len(values.get('chemical_symbols', 'Not specified'))})"
+                f"Length of concentration ({len(v)}) MUST equal length of chemical_symbols "
+                f"({len(values.get('chemical_symbols', []))})"
             )
         return v
 
@@ -227,7 +228,8 @@ def validate_sites_in_groups(cls, v):
     def check_self_consistency(cls, v, values):
         if len(v) != len(values.get("sites_in_groups", [])):
             raise ValueError(
-                f"sites_in_groups and group_probabilities MUST be of same length, but are {len(values.get('sites_in_groups', 'Not specified'))} and {len(v)}, respectively"
+                f"sites_in_groups and group_probabilities MUST be of same length, "
+                f"but are {len(values.get('sites_in_groups', []))} and {len(v)}, respectively"
             )
         return v
 
@@ -825,7 +827,8 @@ def null_values_for_whole_vector(cls, v):
     def validate_nsites(cls, v, values):
         if v != len(values.get("cartesian_site_positions", [])):
             raise ValueError(
-                f"nsites (value: {v}) MUST equal length of cartesian_site_positions (value: {len(values.get('cartesian_site_positions', []))})"
+                f"nsites (value: {v}) MUST equal length of cartesian_site_positions "
+                f"(value: {len(values.get('cartesian_site_positions', []))})"
             )
         return v
 
@@ -837,7 +840,8 @@ def validate_species_at_sites(cls, v, values):
             )
         if len(v) != values.get("nsites", 0):
             raise ValueError(
-                f"Number of species_at_sites (value: {len(v)}) MUST equal number of sites (value: {values.get('nsites', 'Not specified')})"
+                f"Number of species_at_sites (value: {len(v)}) MUST equal number of sites "
+                f"(value: {values.get('nsites', 'Not specified')})"
             )
         all_species_names = {
             getattr(_, "name", None) for _ in values.get("species", [{}])
@@ -846,7 +850,8 @@ def validate_species_at_sites(cls, v, values):
         for value in v:
             if value not in all_species_names:
                 raise ValueError(
-                    f"species_at_sites MUST be represented by a species' name, but {value} was not found in the list of species names: {all_species_names}"
+                    "species_at_sites MUST be represented by a species' name, "
+                    f"but {value} was not found in the list of species names: {all_species_names}"
                 )
         return v
 
@@ -871,13 +876,15 @@ def validate_structure_features(cls, v, values):
             if len(species.chemical_symbols) > 1:
                 if StructureFeatures.DISORDER not in v:
                     raise ValueError(
-                        f"{StructureFeatures.DISORDER.value} MUST be present when any one entry in species has a chemical_symbols list greater than one element"
+                        f"{StructureFeatures.DISORDER.value} MUST be present when any one entry in species "
+                        "has a chemical_symbols list greater than one element"
                     )
                 break
         else:
             if StructureFeatures.DISORDER in v:
                 raise ValueError(
-                    f"{StructureFeatures.DISORDER.value} MUST NOT be present, since all species' chemical_symbols lists are equal to or less than one element"
+                    f"{StructureFeatures.DISORDER.value} MUST NOT be present, since all species' chemical_symbols "
+                    "lists are equal to or less than one element"
                 )
         # assemblies
         if values.get("assemblies", None) is not None:
@@ -888,7 +895,8 @@ def validate_structure_features(cls, v, values):
         else:
             if StructureFeatures.ASSEMBLIES in v:
                 raise ValueError(
-                    f"{StructureFeatures.ASSEMBLIES.value} MUST NOT be present, since the property of the same name is not present"
+                    f"{StructureFeatures.ASSEMBLIES.value} MUST NOT be present, "
+                    "since the property of the same name is not present"
                 )
         # site_attachments
         for species in values.get("species", []):
@@ -897,27 +905,31 @@ def validate_structure_features(cls, v, values):
             if getattr(species, "attached", None) is not None:
                 if StructureFeatures.SITE_ATTACHMENTS not in v:
                     raise ValueError(
-                        f"{StructureFeatures.SITE_ATTACHMENTS.value} MUST be present when any one entry in species includes attached and nattached"
+                        f"{StructureFeatures.SITE_ATTACHMENTS.value} MUST be present when any one entry "
+                        "in species includes attached and nattached"
                     )
                 break
         else:
             if StructureFeatures.SITE_ATTACHMENTS in v:
                 raise ValueError(
-                    f"{StructureFeatures.SITE_ATTACHMENTS.value} MUST NOT be present, since no species includes the attached and nattached fields"
+                    f"{StructureFeatures.SITE_ATTACHMENTS.value} MUST NOT be present, since no species includes "
+                    "the attached and nattached fields"
                 )
         # implicit_atoms
         species_names = [_.name for _ in values.get("species", [])]
         for name in species_names:
             if name not in values.get("species_at_sites", []):
                 if StructureFeatures.IMPLICIT_ATOMS not in v:
                     raise ValueError(
-                        f"{StructureFeatures.IMPLICIT_ATOMS.value} MUST be present when any one entry in species is not represented in species_at_sites"
+                        f"{StructureFeatures.IMPLICIT_ATOMS.value} MUST be present when any one entry in species "
+                        "is not represented in species_at_sites"
                     )
                 break
         else:
             if StructureFeatures.IMPLICIT_ATOMS in v:
                 raise ValueError(
-                    f"{StructureFeatures.IMPLICIT_ATOMS.value} MUST NOT be present, since all species are represented in species_at_sites"
+                    f"{StructureFeatures.IMPLICIT_ATOMS.value} MUST NOT be present, since all species are "
+                    "represented in species_at_sites"
                 )
         return v