Handle special enum values #333

clickhouse_driver/__init__.py

@@ -3,7 +3,7 @@
 from .dbapi import connect
 
 
-VERSION = (0, 2, 8)
+VERSION = (0, 2, 9)
 __version__ = '.'.join(str(x) for x in VERSION)
 
 __all__ = ['Client', 'connect']

clickhouse_driver/columns/enumcolumn.py

@@ -1,20 +1,24 @@
 from enum import Enum
+from collections import OrderedDict
 
 from .. import errors
 from .intcolumn import IntColumn
 
+invalid_names_for_python_enum = frozenset(['mro', ''])
+
 
 class EnumColumn(IntColumn):
     py_types = (Enum, int, str)
 
-    def __init__(self, enum_cls, **kwargs):
-        self.enum_cls = enum_cls
+    def __init__(self, name_by_value, value_by_name, **kwargs):
+        self.name_by_value = name_by_value
+        self.value_by_name = value_by_name
         super(EnumColumn, self).__init__(**kwargs)
 
     def before_write_items(self, items, nulls_map=None):
         null_value = self.null_value
-
-        enum_cls = self.enum_cls
+        name_by_value = self.name_by_value
+        value_by_name = self.value_by_name
 
         for i, item in enumerate(items):
             if nulls_map and nulls_map[i]:
@@ -26,29 +30,29 @@ def before_write_items(self, items, nulls_map=None):
             # Check real enum value
             try:
                 if isinstance(source_value, str):
-                    items[i] = enum_cls[source_value].value
+                    items[i] = value_by_name[source_value]
                 else:
-                    items[i] = enum_cls(source_value).value
+                    items[i] = value_by_name[name_by_value[source_value]]
             except (ValueError, KeyError):
                 choices = ', '.join(
-                    "'{}' = {}".format(x.name.replace("'", r"\'"), x.value)
-                    for x in enum_cls
+                    "'{}' = {}".format(name.replace("'", r"\'"), value)
+                    for name, value in value_by_name.items()
                 )
-                enum_str = '{}({})'.format(enum_cls.__name__, choices)
+                enum_str = '{}({})'.format(self.ch_type, choices)
 
                 raise errors.LogicalError(
                     "Unknown element '{}' for type {}"
                     .format(source_value, enum_str)
                 )
 
     def after_read_items(self, items, nulls_map=None):
-        enum_cls = self.enum_cls
+        name_by_value = self.name_by_value
 
         if nulls_map is None:
-            return tuple(enum_cls(item).name for item in items)
+            return tuple(name_by_value[item] for item in items)
         else:
             return tuple(
-                (None if is_null else enum_cls(items[i]).name)
+                (None if is_null else name_by_value[items[i]])
                 for i, is_null in enumerate(nulls_map)
             )
 
@@ -73,11 +77,13 @@ def create_enum_column(spec, column_options):
         params = spec[7:-1]
         cls = Enum16Column
 
-    return cls(Enum(cls.ch_type, _parse_options(params)), **column_options)
+    name_by_value, value_by_name = _parse_options(params)
+
+    return cls(name_by_value, value_by_name, **column_options)
 
 
 def _parse_options(option_string):
-    options = dict()
+    name_by_value, value_by_name = {}, OrderedDict()
     after_name = False
     escaped = False
     quote_character = None
@@ -93,7 +99,9 @@ def _parse_options(option_string):
             if ch in (' ', '='):
                 pass
             elif ch == ',':
-                options[name] = int(value)
+                value = int(value)
+                name_by_value[value] = name
+                value_by_name[name] = value
                 after_name = False
                 name = ''
                 value = ''  # reset before collecting new option
@@ -114,6 +122,8 @@ def _parse_options(option_string):
                 quote_character = ch
 
     if after_name:
-        options.setdefault(name, int(value))  # append word after last comma
+        value = int(value)
+        name_by_value[value] = name
+        value_by_name[name] = value
 
-    return options
+    return name_by_value, value_by_name

docs/types.rst

@@ -147,12 +147,8 @@ SELECT type: :class:`str`.
         >>> client.execute('SELECT * FROM test')
         [('foo',), ('bar',), ('foo',)]
 
-Currently clickhouse-driver can't handle empty enum value due to Python's `Enum` mechanics.
-Enum member name must be not empty. See `issue`_ and  `workaround`_.
-
-.. _issue: https://github.com/mymarilyn/clickhouse-driver/issues/48
-.. _workaround: https://github.com/mymarilyn/clickhouse-driver/issues/48#issuecomment-412480613
-
+*Starting from version 0.2.9* clickhouse-driver can handle special enum values:
+``mro`` and ``''``.
 
 Array(T)
 --------

tests/columns/test_enum.py

@@ -149,3 +149,27 @@ def test_nullable(self):
                     (None, ), ('hello', ), (None, ), ('world', ),
                 ]
             )
+
+    def test_invalid_python_names(self):
+        data = [(1, ), (2, ), (3, )]
+        with self.create_table("a Enum8('mro' = 1, '' = 2, 'test' = 3)"):
+            self.client.execute(
+                'INSERT INTO test (a) VALUES', data
+            )
+
+            query = 'SELECT * FROM test'
+            inserted = self.emit_cli(query)
+            self.assertEqual(
+                inserted, (
+                    'mro\n'
+                    '\n'
+                    'test\n'
+                )
+            )
+
+            inserted = self.client.execute(query)
+            self.assertEqual(
+                inserted, [
+                    ('mro', ), ('', ), ('test', )
+                ]
+            )