Return current field value when using transformations and returnUnmat…

…ched

adtl/__init__.py

@@ -117,9 +117,10 @@ def get_value_unhashed(row: StrDict, rule: Rule, ctx: Context = None) -> Any:
                 )
             except AdtlTransformationWarning as e:
                 if ctx and ctx.get("returnUnmatched"):
-                    return e.args[0]
-                else:
                     warnings.warn(str(e), AdtlTransformationWarning)
+                    return value
+                else:
+                    logging.error(str(e))
                     return None
             return value
         if value == "":

adtl/transformations.py

@@ -347,6 +347,7 @@ def splitDate(
             AdtlTransformationWarning,
             stacklevel=2,
         )
+        return None
 
 
 def startYear(

docs/specification.md

@@ -54,7 +54,12 @@ if not present in a datafile, following the same syntax as `fieldPattern` key.
   with either "date_" / "_date" in the field name or that have format date
   set in the JSON schema
 * **returnUnmatched**: Returns all values that are not able to be converted
-  according to the provided rules and formats. For fields with [value mappings](#field-with-value-mapping), it is equivalent to using `ignoreMissingKeys`. Fields using [data transformation functions](#data-transformations-(apply)) will return a string describing the failed function and input values.
+  according to the provided rules and formats. For fields with [value mappings](#field-with-value-mapping), it is equivalent to using `ignoreMissingKeys`. Fields using [data transformation functions](#data-transformations-(apply)) will issue a warning to the 
+  terminal describing the error in the transformation. Transformations requiring multiple
+  parameters will only return the current field value that was not transformed.
+  > :warning: This is likely to return columns with non-matching datatypes. External json
+  validation may fail, as will attempting to use the `--parquet` option to save outputs as
+  parquet files (which required a consistent type down each column).
 
 ## Validation
 

tests/__snapshots__/test_parser.ambr

@@ -50,7 +50,7 @@
 # name: test_return_unmapped
   '''
   age,date_death,date_of_birth,diabetes_type,has_smoking,pregnancy_birth_weight_kg,subject_id
-  fifteen,"Could not construct date from: year=2023, month=11, day=80",2023-11-20,No matches found for: 'no diabetes',today,eight,1
+  fifteen,2023,2023-11-20,no diabetes,today,eight,1
 
   '''
 # ---