Merge pull request #1 from Infinidat/master

Master

README.rst

@@ -34,6 +34,20 @@ It is possible to provide a default value for a field, instead of its "natural"
 
 See below for the supported field types and table engines.
 
+Table Names
+***********
+
+The table name used for the model is its class name, converted to lowercase. To override the default name,
+implement the ``table_name`` method::
+
+    class Person(models.Model):
+
+        ...
+
+        @classmethod
+        def table_name(cls):
+            return 'people'
+
 Using Models
 ------------
 
@@ -151,7 +165,7 @@ The ``paginate`` method returns a ``namedtuple`` containing the following fields
 - ``objects`` - the list of objects in this page
 - ``number_of_objects`` - total number of objects in all pages
 - ``pages_total`` - total number of pages
-- ``number`` - the page number
+- ``number`` - the page number, starting from 1; the special value -1 may be used to retrieve the last page
 - ``page_size`` - the number of objects per page
 
 You can optionally pass conditions to the query::
@@ -191,8 +205,50 @@ UInt32Field    UInt32      int                Range 0 to 4294967295
 UInt64Field    UInt64      int/long           Range 0 to 18446744073709551615
 Float32Field   Float32     float
 Float64Field   Float64     float
+Enum8Field     Enum8       Enum               See below
+Enum16Field    Enum16      Enum               See below
+ArrayField     Array       list               See below
 =============  ========    =================  ===================================================
 
+Working with enum fields
+************************
+
+``Enum8Field`` and ``Enum16Field`` provide support for working with ClickHouse enum columns. They accept
+strings or integers as values, and convert them to the matching Pythonic Enum member.
+
+Python 3.4 and higher supports Enums natively. When using previous Python versions you 
+need to install the `enum34` library.
+
+Example of a model with an enum field::
+
+    Gender = Enum('Gender', 'male female unspecified')
+
+    class Person(models.Model):
+
+        first_name = fields.StringField()
+        last_name = fields.StringField()
+        birthday = fields.DateField()
+        gender = fields.Enum32Field(Gender)
+
+        engine = engines.MergeTree('birthday', ('first_name', 'last_name', 'birthday'))
+
+    suzy = Person(first_name='Suzy', last_name='Jones', gender=Gender.female)
+
+Working with array fields
+*************************
+
+You can create array fields containing any data type, for example::
+
+    class SensorData(models.Model):
+
+        date = fields.DateField()
+        temperatures = fields.ArrayField(fields.Float32Field())
+        humidity_levels = fields.ArrayField(fields.UInt8Field())
+
+        engine = engines.MergeTree('date', ('date',))
+
+    data = SensorData(date=date.today(), temperatures=[25.5, 31.2, 28.7], humidity_levels=[41, 39, 66])
+
 Table Engines
 -------------
 

buildout.cfg

@@ -45,6 +45,8 @@ recipe = infi.recipe.console_scripts
 eggs = ${project:name}
 	ipython
 	nose
+	coverage
+	enum34
 	infi.unittest
 	infi.traceback
 	zc.buildout

src/infi/clickhouse_orm/database.py

@@ -18,12 +18,20 @@ class DatabaseException(Exception):
 
 class Database(object):
 
-    def __init__(self, db_name, db_url='http://localhost:8123/', username=None, password=None):
+    def __init__(self, db_name, db_url='http://localhost:8123/', username=None, password=None, readonly=False):
         self.db_name = db_name
         self.db_url = db_url
         self.username = username
         self.password = password
-        self._send('CREATE DATABASE IF NOT EXISTS `%s`' % db_name)
+        self.readonly = readonly
+        if not self.readonly:
+            self.create_database()
+
+    def create_database(self):
+        self._send('CREATE DATABASE IF NOT EXISTS `%s`' % self.db_name)
+
+    def drop_database(self):
+        self._send('DROP DATABASE `%s`' % self.db_name)
 
     def create_table(self, model_class):
         # TODO check that model has an engine
@@ -32,10 +40,7 @@ class Database(object):
     def drop_table(self, model_class):
         self._send(model_class.drop_table_sql(self.db_name))
 
-    def drop_database(self):
-        self._send('DROP DATABASE `%s`' % self.db_name)
-
-    def insert(self, model_instances):
+    def insert(self, model_instances, batch_size=1000):
         from six import next
         i = iter(model_instances)
         try:
@@ -45,11 +50,19 @@ class Database(object):
         model_class = first_instance.__class__
         def gen():
             yield self._substitute('INSERT INTO $table FORMAT TabSeparated\n', model_class).encode('utf-8')
-            yield first_instance.to_tsv().encode('utf-8')
-            yield '\n'.encode('utf-8')
+            yield (first_instance.to_tsv() + '\n').encode('utf-8')
+            # Collect lines in batches of batch_size
+            batch = []
             for instance in i:
-                yield instance.to_tsv().encode('utf-8')
-                yield '\n'.encode('utf-8')
+                batch.append(instance.to_tsv())
+                if len(batch) >= batch_size:
+                    # Return the current batch of lines
+                    yield ('\n'.join(batch) + '\n').encode('utf-8')
+                    # Start a new batch
+                    batch = []
+            # Return any remaining lines in partial batch
+            if batch:
+                yield ('\n'.join(batch) + '\n').encode('utf-8')
         self._send(gen())
 
     def count(self, model_class, conditions=None):
@@ -74,6 +87,10 @@ class Database(object):
     def paginate(self, model_class, order_by, page_num=1, page_size=100, conditions=None, settings=None):
         count = self.count(model_class, conditions)
         pages_total = int(ceil(count / float(page_size)))
+        if page_num == -1:
+            page_num = pages_total
+        elif page_num < 1:
+            raise ValueError('Invalid page number: %d' % page_num)
         offset = (page_num - 1) * page_size
         query = 'SELECT * FROM $table'
         if conditions:

src/infi/clickhouse_orm/fields.py

@@ -3,6 +3,8 @@ import datetime
 import pytz
 import time
 
+from .utils import escape, parse_array
+
 
 class Field(object):
 
@@ -13,7 +15,7 @@ class Field(object):
     def __init__(self, default=None):
         self.creation_counter = Field.creation_counter
         Field.creation_counter += 1
-        self.default = default or self.class_default
+        self.default = self.class_default if default is None else default
 
     def to_python(self, value):
         '''
@@ -36,11 +38,22 @@ class Field(object):
         if value < min_value or value > max_value:
             raise ValueError('%s out of range - %s is not between %s and %s' % (self.__class__.__name__, value, min_value, max_value))
 
-    def get_db_prep_value(self, value):
+    def to_db_string(self, value, quote=True):
         '''
-        Returns the field's value prepared for interacting with the database.
+        Returns the field's value prepared for writing to the database.
+        When quote is true, strings are surrounded by single quotes.
         '''
-        return value
+        return escape(value, quote)
+
+    def get_sql(self, with_default=True):
+        '''
+        Returns an SQL expression describing the field (e.g. for CREATE TABLE).
+        '''
+        if with_default:
+            default = self.to_db_string(self.default)
+            return '%s DEFAULT %s' % (self.db_type, default)
+        else:
+            return self.db_type
 
 
 class StringField(Field):
@@ -66,6 +79,8 @@ class DateField(Field):
     def to_python(self, value):
         if isinstance(value, datetime.date):
             return value
+        if isinstance(value, datetime.datetime):
+            return value.date()
         if isinstance(value, int):
             return DateField.class_default + datetime.timedelta(days=value)
         if isinstance(value, string_types):
@@ -77,8 +92,8 @@ class DateField(Field):
     def validate(self, value):
         self._range_check(value, DateField.min_value, DateField.max_value)
 
-    def get_db_prep_value(self, value):
-        return value.isoformat()
+    def to_db_string(self, value, quote=True):
+        return escape(value.isoformat(), quote)
 
 
 class DateTimeField(Field):
@@ -94,11 +109,13 @@ class DateTimeField(Field):
         if isinstance(value, int):
             return datetime.datetime.fromtimestamp(value, pytz.utc)
         if isinstance(value, string_types):
+            if value == '0000-00-00 00:00:00':
+                return self.class_default
             return datetime.datetime.strptime(value, '%Y-%m-%d %H:%M:%S')
         raise ValueError('Invalid value for %s - %r' % (self.__class__.__name__, value))
 
-    def get_db_prep_value(self, value):
-        return int(time.mktime(value.timetuple()))
+    def to_db_string(self, value, quote=True):
+        return escape(int(time.mktime(value.timetuple())), quote)
 
 
 class BaseIntField(Field):
@@ -187,3 +204,94 @@ class Float64Field(BaseFloatField):
 
     db_type = 'Float64'
 
+
+class BaseEnumField(Field):
+
+    def __init__(self, enum_cls, default=None):
+        self.enum_cls = enum_cls
+        if default is None:
+            default = list(enum_cls)[0]
+        super(BaseEnumField, self).__init__(default)
+
+    def to_python(self, value):
+        if isinstance(value, self.enum_cls):
+            return value
+        try:
+            if isinstance(value, text_type):
+                return self.enum_cls[value]
+            if isinstance(value, binary_type):
+                return self.enum_cls[value.decode('UTF-8')]
+            if isinstance(value, int):
+                return self.enum_cls(value)
+        except (KeyError, ValueError):
+            pass
+        raise ValueError('Invalid value for %s: %r' % (self.enum_cls.__name__, value))
+
+    def to_db_string(self, value, quote=True):
+        return escape(value.name, quote)
+
+    def get_sql(self, with_default=True):
+        values = ['%s = %d' % (escape(item.name), item.value) for item in self.enum_cls]
+        sql = '%s(%s)' % (self.db_type, ' ,'.join(values))
+        if with_default:
+            default = self.to_db_string(self.default)
+            sql = '%s DEFAULT %s' % (sql, default)
+        return sql
+
+    @classmethod
+    def create_ad_hoc_field(cls, db_type):
+        '''
+        Give an SQL column description such as "Enum8('apple' = 1, 'banana' = 2, 'orange' = 3)"
+        this method returns a matching enum field.
+        '''
+        import re
+        try:
+            Enum # exists in Python 3.4+
+        except NameError:
+            from enum import Enum # use the enum34 library instead
+        members = {}
+        for match in re.finditer("'(\w+)' = (\d+)", db_type):
+            members[match.group(1)] = int(match.group(2))
+        enum_cls = Enum('AdHocEnum', members)
+        field_class = Enum8Field if db_type.startswith('Enum8') else Enum16Field
+        return field_class(enum_cls)
+
+
+class Enum8Field(BaseEnumField):
+
+    db_type = 'Enum8'
+
+
+class Enum16Field(BaseEnumField):
+
+    db_type = 'Enum16'
+
+
+class ArrayField(Field):
+
+    class_default = []
+
+    def __init__(self, inner_field, default=None):
+        self.inner_field = inner_field
+        super(ArrayField, self).__init__(default)
+
+    def to_python(self, value):
+        if isinstance(value, text_type):
+            value = parse_array(value)
+        elif isinstance(value, binary_type):
+            value = parse_array(value.decode('UTF-8'))
+        elif not isinstance(value, (list, tuple)):
+            raise ValueError('ArrayField expects list or tuple, not %s' % type(value))
+        return [self.inner_field.to_python(v) for v in value]
+
+    def validate(self, value):
+        for v in value:
+            self.inner_field.validate(v)
+
+    def to_db_string(self, value, quote=True):
+        array = [self.inner_field.to_db_string(v, quote=True) for v in value]
+        return '[' + ', '.join(array) + ']'
+
+    def get_sql(self, with_default=True):
+        from .utils import escape
+        return 'Array(%s)' % self.inner_field.get_sql(with_default=False)

src/infi/clickhouse_orm/migrations.py

@@ -68,12 +68,11 @@ class AlterTable(Operation):
             if name not in table_fields:
                 logger.info('        Add column %s', name)
                 assert prev_name, 'Cannot add a column to the beginning of the table'
-                default = field.get_db_prep_value(field.default)
-                cmd = 'ADD COLUMN %s %s DEFAULT %s AFTER %s' % (name, field.db_type, escape(default), prev_name)
+                cmd = 'ADD COLUMN %s %s AFTER %s' % (name, field.get_sql(), prev_name)
                 self._alter_table(database, cmd)
             prev_name = name
         # Identify fields whose type was changed
-        model_fields = [(name, field.db_type) for name, field in self.model_class._fields]
+        model_fields = [(name, field.get_sql(with_default=False)) for name, field in self.model_class._fields]
         for model_field, table_field in zip(model_fields, self._get_table_fields(database)):
             assert model_field[0] == table_field[0], 'Model fields and table columns in disagreement'
             if model_field[1] != table_field[1]:

src/infi/clickhouse_orm/models.py

@@ -4,6 +4,9 @@ from .fields import Field
 
 from six import with_metaclass
 
+from logging import getLogger
+logger = getLogger('clickhouse_orm')
+
 
 class ModelBase(type):
     '''
@@ -28,7 +31,6 @@ class ModelBase(type):
     @classmethod
     def create_ad_hoc_model(cls, fields):
         # fields is a list of tuples (name, db_type)
-        import infi.clickhouse_orm.fields as orm_fields
         # Check if model exists in cache
         fields = list(fields)
         cache_key = str(fields)
@@ -37,15 +39,28 @@ class ModelBase(type):
         # Create an ad hoc model class
         attrs = {}
         for name, db_type in fields:
-            field_class = db_type + 'Field'
-            if not hasattr(orm_fields, field_class):
-                raise NotImplementedError('No field class for %s' % db_type)
-            attrs[name] = getattr(orm_fields, field_class)()
+            attrs[name] = cls.create_ad_hoc_field(db_type)
         model_class = cls.__new__(cls, 'AdHocModel', (Model,), attrs)
         # Add the model class to the cache
         cls.ad_hoc_model_cache[cache_key] = model_class
         return model_class
 
+    @classmethod
+    def create_ad_hoc_field(cls, db_type):
+        import infi.clickhouse_orm.fields as orm_fields
+        # Enums
+        if db_type.startswith('Enum'):
+            return orm_fields.BaseEnumField.create_ad_hoc_field(db_type)
+        # Arrays
+        if db_type.startswith('Array'):
+            inner_field = cls.create_ad_hoc_field(db_type[6 : -1])
+            return orm_fields.ArrayField(inner_field)
+        # Simple fields
+        name = db_type + 'Field'
+        if not hasattr(orm_fields, name):
+            raise NotImplementedError('No field class for %s' % db_type)
+        return getattr(orm_fields, name)()
+
 
 class Model(with_metaclass(ModelBase)):
     '''
@@ -107,8 +122,7 @@ class Model(with_metaclass(ModelBase)):
         parts = ['CREATE TABLE IF NOT EXISTS `%s`.`%s` (' % (db_name, cls.table_name())]
         cols = []
         for name, field in cls._fields:
-            default = field.get_db_prep_value(field.default)
-            cols.append('    %s %s DEFAULT %s' % (name, field.db_type, escape(default)))
+            cols.append('    %s %s' % (name, field.get_sql()))
         parts.append(',\n'.join(cols))
         parts.append(')')
         parts.append('ENGINE = ' + cls.engine.create_table_sql())
@@ -140,8 +154,5 @@ class Model(with_metaclass(ModelBase)):
         '''
         Returns the instance's column values as a tab-separated line. A newline is not included.
         '''
-        parts = []
-        for name, field in self._fields:
-            value = field.get_db_prep_value(field.to_python(getattr(self, name)))
-            parts.append(escape(value, quote=False))
-        return '\t'.join(parts)
+        data = self.__dict__
+        return '\t'.join(field.to_db_string(data[name], quote=False) for name, field in self._fields)

src/infi/clickhouse_orm/utils.py

@@ -1,5 +1,6 @@
 from six import string_types, binary_type, text_type, PY3
 import codecs
+import re
 
 
 SPECIAL_CHARS = {
@@ -13,11 +14,20 @@ SPECIAL_CHARS = {
     "'"  : "\\'"
 }
 
+SPECIAL_CHARS_REGEX = re.compile("[" + ''.join(SPECIAL_CHARS.values()) + "]")
+
 
 def escape(value, quote=True):
+    '''
+    If the value is a string, escapes any special characters and optionally
+    surrounds it with single quotes. If the value is not a string (e.g. a number), 
+    converts it to one.
+    '''
     if isinstance(value, string_types):
-        chars = (SPECIAL_CHARS.get(c, c) for c in value)
-        value = "'" + "".join(chars) + "'" if quote else "".join(chars)
+        if SPECIAL_CHARS_REGEX.search(value):
+            value = "".join(SPECIAL_CHARS.get(c, c) for c in value)
+        if quote:
+            value = "'" + value + "'"
     return text_type(value)
 
 
@@ -33,6 +43,40 @@ def parse_tsv(line):
     return [unescape(value) for value in line.split('\t')]
 
 
+def parse_array(array_string):
+    """
+    Parse an array string as returned by clickhouse. For example:
+        "['hello', 'world']" ==> ["hello", "world"]
+        "[1,2,3]"            ==> [1, 2, 3]
+    """
+    # Sanity check
+    if len(array_string) < 2 or array_string[0] != '[' or array_string[-1] != ']':
+        raise ValueError('Invalid array string: "%s"' % array_string)
+    # Drop opening brace
+    array_string = array_string[1:] 
+    # Go over the string, lopping off each value at the beginning until nothing is left
+    values = []
+    while True:
+        if array_string == ']':
+            # End of array
+            return values
+        elif array_string[0] in ', ':
+            # In between values
+            array_string = array_string[1:] 
+        elif array_string[0] == "'":
+            # Start of quoted value, find its end
+            match = re.search(r"[^\\]'", array_string)
+            if match is None:
+                raise ValueError('Missing closing quote: "%s"' % array_string)
+            values.append(array_string[1 : match.start() + 1])
+            array_string = array_string[match.end():]
+        else:
+            # Start of non-quoted value, find its end
+            match = re.search(r",|\]", array_string)
+            values.append(array_string[0 : match.start()])
+            array_string = array_string[match.end() - 1:]
+
+
 def import_submodules(package_name):
     """
     Import all submodules of a module.

tests/sample_migrations/0006.py

@@ -0,0 +1,6 @@
+from infi.clickhouse_orm import migrations
+from ..test_migrations import *
+
+operations = [
+    migrations.CreateTable(EnumModel1)
+]

tests/sample_migrations/0007.py

@@ -0,0 +1,6 @@
+from infi.clickhouse_orm import migrations
+from ..test_migrations import *
+
+operations = [
+    migrations.AlterTable(EnumModel2)
+]

tests/test_array_fields.py

@@ -0,0 +1,73 @@
+import unittest
+from datetime import date
+
+from infi.clickhouse_orm.database import Database
+from infi.clickhouse_orm.models import Model
+from infi.clickhouse_orm.fields import *
+from infi.clickhouse_orm.engines import *
+
+
+class ArrayFieldsTest(unittest.TestCase):
+
+    def setUp(self):
+        self.database = Database('test-db')
+        self.database.create_table(ModelWithArrays)
+
+    def tearDown(self):
+        self.database.drop_database()
+
+    def test_insert_and_select(self):
+        instance = ModelWithArrays(
+            date_field='2016-08-30', 
+            arr_str=['goodbye,', 'cruel', 'world', 'special chars: ,"\\\'` \n\t\\[]'], 
+            arr_date=['2010-01-01']
+        )
+        self.database.insert([instance])
+        query = 'SELECT * from $db.modelwitharrays ORDER BY date_field'
+        for model_cls in (ModelWithArrays, None):
+            results = list(self.database.select(query, model_cls))
+            self.assertEquals(len(results), 1)
+            self.assertEquals(results[0].arr_str, instance.arr_str)
+            self.assertEquals(results[0].arr_int, instance.arr_int)
+            self.assertEquals(results[0].arr_date, instance.arr_date)
+
+    def test_conversion(self):
+        instance = ModelWithArrays(
+            arr_int=('1', '2', '3'),
+            arr_date=['2010-01-01']
+        )
+        self.assertEquals(instance.arr_str, [])
+        self.assertEquals(instance.arr_int, [1, 2, 3])
+        self.assertEquals(instance.arr_date, [date(2010, 1, 1)])
+
+    def test_assignment_error(self):
+        instance = ModelWithArrays()
+        for value in (7, 'x', [date.today()], ['aaa'], [None]):
+            with self.assertRaises(ValueError):
+                instance.arr_int = value
+
+    def test_parse_array(self):
+        from infi.clickhouse_orm.utils import parse_array, unescape
+        self.assertEquals(parse_array("[]"), [])
+        self.assertEquals(parse_array("[1, 2, 395, -44]"), ["1", "2", "395", "-44"])
+        self.assertEquals(parse_array("['big','mouse','','!']"), ["big", "mouse", "", "!"])
+        self.assertEquals(parse_array(unescape("['\\r\\n\\0\\t\\b']")), ["\r\n\0\t\b"])
+        for s in ("", 
+                  "[", 
+                  "]", 
+                  "[1, 2", 
+                  "3, 4]", 
+                  "['aaa', 'aaa]"):
+            with self.assertRaises(ValueError):
+                parse_array(s)
+
+
+class ModelWithArrays(Model):
+
+    date_field = DateField()
+    arr_str = ArrayField(StringField())
+    arr_int = ArrayField(Int32Field())
+    arr_date = ArrayField(DateField())
+
+    engine = MergeTree('date_field', ('date_field',))
+

tests/test_database.py

@@ -93,6 +93,23 @@ class DatabaseTestCase(unittest.TestCase):
             # Verify that all instances were returned
             self.assertEquals(len(instances), len(data))
 
+    def test_pagination_last_page(self):
+        self._insert_and_check(self._sample_data(), len(data))
+        # Try different page sizes
+        for page_size in (1, 2, 7, 10, 30, 100, 150):
+            # Ask for the last page in two different ways and verify equality
+            page_a = self.database.paginate(Person, 'first_name, last_name', -1, page_size)
+            page_b = self.database.paginate(Person, 'first_name, last_name', page_a.pages_total, page_size)
+            self.assertEquals(page_a[1:], page_b[1:])
+            self.assertEquals([obj.to_tsv() for obj in page_a.objects], 
+                              [obj.to_tsv() for obj in page_b.objects])
+
+    def test_pagination_invalid_page(self):
+        self._insert_and_check(self._sample_data(), len(data))
+        for page_num in (0, -2, -100):
+            with self.assertRaises(ValueError):
+                self.database.paginate(Person, 'first_name, last_name', page_num, 100)
+
     def test_special_chars(self):
         s = u'אבגד \\\'"`,.;éåäöšž\n\t\0\b\r'
         p = Person(first_name=s)

tests/test_enum_fields.py

@@ -0,0 +1,87 @@
+import unittest
+
+from infi.clickhouse_orm.database import Database
+from infi.clickhouse_orm.models import Model
+from infi.clickhouse_orm.fields import *
+from infi.clickhouse_orm.engines import *
+
+try:
+    Enum # exists in Python 3.4+
+except NameError:
+    from enum import Enum # use the enum34 library instead
+
+
+class EnumFieldsTest(unittest.TestCase):
+
+    def setUp(self):
+        self.database = Database('test-db')
+        self.database.create_table(ModelWithEnum)
+        self.database.create_table(ModelWithEnumArray)
+
+    def tearDown(self):
+        self.database.drop_database()
+
+    def test_insert_and_select(self):
+        self.database.insert([
+            ModelWithEnum(date_field='2016-08-30', enum_field=Fruit.apple),
+            ModelWithEnum(date_field='2016-08-31', enum_field=Fruit.orange)
+        ])
+        query = 'SELECT * from $table ORDER BY date_field'
+        results = list(self.database.select(query, ModelWithEnum))
+        self.assertEquals(len(results), 2)
+        self.assertEquals(results[0].enum_field, Fruit.apple)
+        self.assertEquals(results[1].enum_field, Fruit.orange)
+
+    def test_ad_hoc_model(self):
+        self.database.insert([
+            ModelWithEnum(date_field='2016-08-30', enum_field=Fruit.apple),
+            ModelWithEnum(date_field='2016-08-31', enum_field=Fruit.orange)
+        ])
+        query = 'SELECT * from $db.modelwithenum ORDER BY date_field'
+        results = list(self.database.select(query))
+        self.assertEquals(len(results), 2)
+        self.assertEquals(results[0].enum_field.name, Fruit.apple.name)
+        self.assertEquals(results[0].enum_field.value, Fruit.apple.value)
+        self.assertEquals(results[1].enum_field.name, Fruit.orange.name)
+        self.assertEquals(results[1].enum_field.value, Fruit.orange.value)
+
+    def test_conversion(self):
+        self.assertEquals(ModelWithEnum(enum_field=3).enum_field, Fruit.orange)
+        self.assertEquals(ModelWithEnum(enum_field='apple').enum_field, Fruit.apple)
+        self.assertEquals(ModelWithEnum(enum_field=Fruit.banana).enum_field, Fruit.banana)
+
+    def test_assignment_error(self):
+        for value in (0, 17, 'pear', '', None, 99.9):
+            with self.assertRaises(ValueError):
+                ModelWithEnum(enum_field=value)
+
+    def test_default_value(self):
+        instance = ModelWithEnum()
+        self.assertEquals(instance.enum_field, Fruit.apple)
+
+    def test_enum_array(self):
+        instance = ModelWithEnumArray(date_field='2016-08-30', enum_array=[Fruit.apple, Fruit.apple, Fruit.orange])
+        self.database.insert([instance])
+        query = 'SELECT * from $table ORDER BY date_field'
+        results = list(self.database.select(query, ModelWithEnumArray))
+        self.assertEquals(len(results), 1)
+        self.assertEquals(results[0].enum_array, instance.enum_array)
+
+
+Fruit = Enum('Fruit', u'apple banana orange')
+
+
+class ModelWithEnum(Model):
+
+    date_field = DateField()
+    enum_field = Enum8Field(Fruit)
+
+    engine = MergeTree('date_field', ('date_field',))
+
+
+class ModelWithEnumArray(Model):
+
+    date_field = DateField()
+    enum_array = ArrayField(Enum16Field(Fruit))
+
+    engine = MergeTree('date_field', ('date_field',))

tests/test_migrations.py

@@ -10,6 +10,11 @@ from infi.clickhouse_orm.migrations import MigrationHistory
 import sys, os
 sys.path.append(os.path.dirname(__file__))
 
+try:
+    Enum # exists in Python 3.4+
+except NameError:
+    from enum import Enum # use the enum34 library instead
+
 import logging
 logging.basicConfig(level=logging.DEBUG, format='%(message)s')
 logging.getLogger("requests").setLevel(logging.WARNING)
@@ -21,6 +26,9 @@ class MigrationsTestCase(unittest.TestCase):
         self.database = Database('test-db')
         self.database.drop_table(MigrationHistory)
 
+    def tearDown(self):
+        self.database.drop_database()
+
     def tableExists(self, model_class):
         query = "EXISTS TABLE $db.`%s`" % model_class.table_name()
         return next(self.database.select(query)).result == 1
@@ -30,18 +38,28 @@ class MigrationsTestCase(unittest.TestCase):
         return [(row.name, row.type) for row in self.database.select(query)]
 
     def test_migrations(self):
+        # Creation and deletion of table
         self.database.migrate('tests.sample_migrations', 1)
         self.assertTrue(self.tableExists(Model1))
         self.database.migrate('tests.sample_migrations', 2)
         self.assertFalse(self.tableExists(Model1))
         self.database.migrate('tests.sample_migrations', 3)
         self.assertTrue(self.tableExists(Model1))
+        # Adding, removing and altering simple fields
         self.assertEquals(self.getTableFields(Model1), [('date', 'Date'), ('f1', 'Int32'), ('f2', 'String')])
         self.database.migrate('tests.sample_migrations', 4)
         self.assertEquals(self.getTableFields(Model2), [('date', 'Date'), ('f1', 'Int32'), ('f3', 'Float32'), ('f2', 'String'), ('f4', 'String')])
         self.database.migrate('tests.sample_migrations', 5)
         self.assertEquals(self.getTableFields(Model3), [('date', 'Date'), ('f1', 'Int64'), ('f3', 'Float64'), ('f4', 'String')])
-
+        # Altering enum fields
+        self.database.migrate('tests.sample_migrations', 6)
+        self.assertTrue(self.tableExists(EnumModel1))
+        self.assertEquals(self.getTableFields(EnumModel1), 
+                          [('date', 'Date'), ('f1', "Enum8('dog' = 1, 'cat' = 2, 'cow' = 3)")])
+        self.database.migrate('tests.sample_migrations', 7)
+        self.assertTrue(self.tableExists(EnumModel1))
+        self.assertEquals(self.getTableFields(EnumModel2), 
+                          [('date', 'Date'), ('f1', "Enum16('dog' = 1, 'cat' = 2, 'horse' = 3, 'pig' = 4)")])
 
 # Several different models with the same table name, to simulate a table that changes over time
 
@@ -86,3 +104,26 @@ class Model3(Model):
     def table_name(cls):
         return 'mig'
 
+
+class EnumModel1(Model):
+
+    date = DateField()
+    f1 = Enum8Field(Enum('SomeEnum1', 'dog cat cow'))
+
+    engine = MergeTree('date', ('date',))
+
+    @classmethod
+    def table_name(cls):
+        return 'enum_mig'
+
+
+class EnumModel2(Model):
+
+    date = DateField()
+    f1 = Enum16Field(Enum('SomeEnum2', 'dog cat horse pig')) # changed type and values
+
+    engine = MergeTree('date', ('date',))
+
+    @classmethod
+    def table_name(cls):
+        return 'enum_mig'