avro: also improve TypeError handling

petl/io/avro.py

@@ -334,9 +334,12 @@ def _write_toavro(table, target, mode, schema, sample,
             try:
                 writer.write(record)
                 num = num + 1
-            except ValueError as err:
-                details = _get_error_details(target, num, err, record, schema)
-                _raise_error(details)
+            except ValueError as verr:
+                vmsg = _get_error_details(target, num, verr, record, schema)
+                _raise_error(ValueError, vmsg)
+            except TypeError as terr:
+                tmsg = _get_error_details(target, num, terr, record, schema)
+                _raise_error(TypeError, tmsg)
         # finish writing
         writer.flush()
 
@@ -541,14 +544,18 @@ def _get_schema_header_names(schema):
     return header
 
 
-def _raise_error(details):
-    if PY3:
-        raise ValueError(details).with_traceback(sys.exc_info()[2])
-    else:
-        import traceback
-        stacktrace = traceback.format_exc(sys.exc_info())
-        err = "%s%s" % (stacktrace, details)
-        raise ValueError(err)
+def _raise_error(ErrorType, new_message):
+    """Works like raise Excetion(msg) from prev_exp in python3."""
+    exinf = sys.exc_info()
+    tracebk = exinf[2]
+    try:
+        if PY3:
+            raise ErrorType(new_message).with_traceback(tracebk)
+        # Python2 compatibility workaround
+        exec('raise ErrorType, new_message, tracebk')
+    finally:
+        exinf = None
+        tracebk = None  # noqa: F841
 
 
 def _ordered_dict_iterator(table):

petl/test/io/test_avro.py

@@ -101,14 +101,27 @@ def test_appendavro22():
     def test_appendavro10():
         _append_to_avro_file(table11, table12, schema1)
 
-    def test_toavro_troubleshooting():
-        wrong_schema = dict(schema0)
-        schema_fields = wrong_schema['fields']
+    def test_toavro_troubleshooting10():
+        nullable_schema = dict(schema0)
+        schema_fields = nullable_schema['fields']
         for field in schema_fields:
             field['type'] = ['null', 'string']
         try:
-            _write_temp_avro_file(table1, wrong_schema)
-        except ValueError:
+            _write_temp_avro_file(table1, nullable_schema)
+        except ValueError as vex:
+            bob = "%s" % vex
+            assert 'Bob' in bob
+            return
+        assert False, 'Failed schema conversion'
+
+    def test_toavro_troubleshooting11():
+        table0 = list(table1)
+        table0[3][1] = None
+        try:
+            _write_temp_avro_file(table0, schema1)
+        except TypeError as tex:
+            joe = "%s" % tex
+            assert 'Joe' in joe
             return
         assert False, 'Failed schema conversion'