document exception sources better

common-workflow-language · Sep 13, 2021 · f1f465c · f1f465c
1 parent f91d883
commit f1f465c
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Showing 2 changed files with 12 additions and 8 deletions.
diff --git a/schema_salad/avro/schema.py b/schema_salad/avro/schema.py
@@ -303,8 +303,8 @@ def __init__(
                 type_schema = make_avsc_object(atype, names)
             except Exception as e:
                 raise SchemaParseException(
-                    f'Type property "{atype}" not a valid Avro schema: {e}'
-                )
+                    f'Type property "{atype}" not a valid Avro schema.'
+                ) from e
         self.set_prop("type", type_schema)
         self.set_prop("name", name)
         self.type = type_schema
@@ -409,9 +409,9 @@ def __init__(
                 items_schema = make_avsc_object(items, names)
             except Exception as err:
                 raise SchemaParseException(
-                    "Items schema ({}) not a valid Avro schema: {} (known "
-                    "names: {})".format(items, err, list(names.names.keys()))
-                )
+                    f"Items schema ({items}) not a valid Avro schema: (known "
+                    f"names: {list(names.names.keys())})."
+                ) from err
 
         self.set_prop("items", items_schema)
 
@@ -451,8 +451,8 @@ def __init__(
                     new_schema = make_avsc_object(schema, names)
                 except Exception as err:
                     raise SchemaParseException(
-                        f"Union item must be a valid Avro schema: {err}. {schema}"
-                    )
+                        f"Union item must be a valid Avro schema: {schema}"
+                    ) from err
             # check the new schema
             if (
                 new_schema.type in VALID_TYPES

diff --git a/schema_salad/validate.py b/schema_salad/validate.py
@@ -121,6 +121,7 @@ def validate_ex(
     # type: (...) -> bool
     """Determine if a python datum is an instance of a schema."""
 
+    debug = _logger.isEnabledFor(logging.DEBUG)
     if not identifiers:
         identifiers = []
 
@@ -228,7 +229,10 @@ def validate_ex(
                         return False
                 except ValidationException as v:
                     if raise_ex:
-                        raise ValidationException("item is invalid because", sl, [v])
+                        source = v if debug else None
+                        raise ValidationException(
+                            "item is invalid because", sl, [v]
+                        ) from source
                     return False
             return True
         else: