ENH: Better error output in case of wrong server XML.

src/caosdb/common/models.py

@@ -55,6 +55,7 @@ from caosdb.exceptions import (AmbiguousEntityError, AuthorizationError,
                                EntityDoesNotExistError, EntityError,
                                EntityHasNoDatatypeError, HTTPURITooLongError,
                                MismatchingEntitiesError, QueryNotUniqueError,
+                               ServerConfigurationException,
                                TransactionError, UniqueNamesError,
                                UnqualifiedParentsError,
                                UnqualifiedPropertiesError)
@@ -1195,6 +1196,10 @@ class Entity(object):
 
 
 def _parse_value(datatype, value):
+    """Parse the value (from XML input) according to the given datatype
+    """
+
+    # Simple values
     if value is None:
         return value
 
@@ -1215,12 +1220,12 @@ def _parse_value(datatype, value):
         else:
             raise ValueError("Boolean value was {}.".format(value))
 
+    # Datetime and text are returned as-is
     if datatype in [DATETIME, TEXT]:
         if isinstance(value, str):
             return value
 
     # deal with collections
-
     if isinstance(datatype, str):
         matcher = re.compile(r"^(?P<col>[^<]+)<(?P<dt>[^>]+)>$")
         m = matcher.match(datatype)
@@ -1245,12 +1250,10 @@ def _parse_value(datatype, value):
 
     # This is for a special case, where the xml parser could not differentiate
     # between single values and lists with one element. As
-
     if hasattr(value, "__len__") and len(value) == 1:
         return _parse_value(datatype, value[0])
 
     # deal with references
-
     if isinstance(value, Entity):
         return value
 
@@ -1266,6 +1269,12 @@ def _parse_value(datatype, value):
             # reference via name
 
             return str(value)
+        except TypeError:
+            # deal with invalid XML: List of values without appropriate datatype
+            if isinstance(value, list):
+                raise ServerConfigurationException(
+                    "The server sent an invalid XML: List valued properties must be announced by "
+                    "the datatype.\n" + f"Datatype: {datatype}\nvalue: {value}")
 
 
 def _log_request(request, xml_body=None):

unittests/data/list_in_value.xml

@@ -8,3 +8,5 @@
     <Value>1005</Value>
   </Property>
 </Record>
+
+<!-- Note: This XML is invalid, because list-valued Properties must have a LIST-Datatype -->

unittests/test_issues.py

@@ -24,10 +24,16 @@ import os
 import lxml
 import caosdb as db
 
+from pytest import raises
+
 
 def test_issue_100():
     """_parse_value() fails for some list-valued content
     """
+
+    # Parse from (invalid) XML file
     filename = os.path.join(os.path.dirname(__file__), "data", "list_in_value.xml")
     xml_el = lxml.etree.parse(filename).getroot()
-    rec = db.common.models._parse_single_xml_element(xml_el)
+    with raises(db.ServerConfigurationException) as exc_info:
+        db.common.models._parse_single_xml_element(xml_el)
+    assert "invalid XML: List valued properties" in exc_info.value.msg