Add support for enum fields

README.rst

@@ -191,8 +191,34 @@ 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
 =============  ========    =================  ===================================================
 
+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)
+
 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/fields.py

@@ -13,7 +13,7 @@ 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):
         '''
@@ -42,6 +42,17 @@ class Field(object):
         '''
         return value
 
+    def get_sql(self, with_default=True):
+        '''
+        Returns an SQL expression describing the field (e.g. for CREATE TABLE).
+        '''
+        from .utils import escape
+        if with_default:
+            default = self.get_db_prep_value(self.default)
+            return '%s DEFAULT %s' % (self.db_type, escape(default))
+        else:
+            return self.db_type
+
 
 class StringField(Field):
 
@@ -187,3 +198,67 @@ 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 get_db_prep_value(self, value):
+        return value.name
+
+    def get_sql(self, with_default=True):
+        from .utils import escape
+        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.get_db_prep_value(self.default)
+            sql = '%s DEFAULT %s' % (sql, escape(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'
+
+

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

@@ -37,6 +37,9 @@ class ModelBase(type):
         # Create an ad hoc model class
         attrs = {}
         for name, db_type in fields:
+            if db_type.startswith('Enum'):
+                attrs[name] = orm_fields.BaseEnumField.create_ad_hoc_field(db_type)
+            else:
                 field_class = db_type + 'Field'
                 if not hasattr(orm_fields, field_class):
                     raise NotImplementedError('No field class for %s' % db_type)
@@ -107,8 +110,7 @@ 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())

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_enum_fields.py

@@ -0,0 +1,69 @@
+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)
+
+    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.value, Fruit.apple.value)
+        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)
+
+
+Fruit = Enum('Fruit', u'apple banana orange')
+
+
+class ModelWithEnum(Model):
+
+    date_field = DateField()
+    enum_field = Enum8Field(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'