Improvements to parser error handling.

gis_metadata/exceptions.py

@@ -1,14 +1,17 @@
-""" A module to define custom exceptions """
+""" A module to define metadata parsing exceptions """
 
 
 class ParserError(Exception):
     """ A class to encapsulate all parsing exceptions """
 
-    def __init__(self, msg_format, *args, **kwargs):
+    def __init__(self, msg_format, invalid=None, missing=None, **kwargs):
         """
         Call Exception with a message formatted with named arguments from
         a Dictionary with values by key, or a list of named parameters.
         """
-        Exception.__init__(self, msg_format.format(*args, **kwargs))
 
+        super(ParserError, self).__init__(msg_format.format(**kwargs))
 
+        # Track details about the error for handling downstream
+        self.invalid = {} if invalid is None else invalid
+        self.missing = [] if missing is None else missing

gis_metadata/metadata_parser.py

@@ -110,7 +110,7 @@ def get_parsed_content(metadata_content):
     if xml_tree is None:
         raise ParserError(
             'Cannot instantiate a {parser_type} parser with invalid content to parse',
-            parser_type=type(metadata_content)
+            parser_type=type(metadata_content).__name__
         )
 
     xml_root = get_element_name(xml_tree)

gis_metadata/utils.py

@@ -639,14 +639,17 @@ def validate_properties(props, required):
     required = set(required or _supported_props)
 
     if len(required.intersection(props)) < len(required):
-        raise ParserError('Missing property names: {props}', props=','.join(required - props))
+        missing = required - props
+        raise ParserError(
+            'Missing property names: {props}', props=','.join(missing), missing=missing
+        )
 
 
 def validate_type(prop, value, expected):
     """ Default validation for all types """
 
     if not isinstance(value, expected):
-        _validation_error(prop, type(value), None, expected)
+        _validation_error(prop, type(value).__name__, None, expected)
 
 
 def _validation_error(prop, prop_type, prop_value, expected):
@@ -661,7 +664,8 @@ def _validation_error(prop, prop_type, prop_value, expected):
 
     raise ParserError(
         'Invalid property {attrib} for {prop}:\n\t{attrib}: {assigned}\n\texpected: {expected}',
-        attrib=attrib, prop=prop, assigned=assigned, expected=expected
+        attrib=attrib, prop=prop, assigned=assigned, expected=expected,
+        invalid={prop: prop_value} if attrib == 'value' else {}
     )