added missing functionality to cratedialect

CHANGES.txt

@@ -5,6 +5,10 @@ Changes for crate
 Unreleased
 ==========
 
+ - added missing functionality in CrateDialect, containing:
+   default schema name, server version info,
+   check if table/schema exists, list all tables/schemas
+
  - run tests against crate 0.46.1
 
 2014/10/27 0.12.3

src/crate/client/sqlalchemy/dialect.py

@@ -23,16 +23,16 @@
 import logging
 from datetime import datetime, date
 
-from sqlalchemy.engine import default
+from sqlalchemy import sql
 from sqlalchemy import types as sqltypes
+from sqlalchemy.engine import default, reflection
 
 from .compiler import CrateCompiler
 from crate.client.exceptions import TimezoneUnawareException
 
 
 log = logging.getLogger(__name__)
 
-
 class Date(sqltypes.Date):
     def bind_processor(self, dialect):
         def process(value):
@@ -116,15 +116,17 @@ class CrateDialect(default.DefaultDialect):
 
     def __init__(self, *args, **kwargs):
         super(CrateDialect, self).__init__(*args, **kwargs)
-
         # currently our sql parser doesn't support unquoted column names that
         # start with _. Adding it here causes sqlalchemy to quote such columns
         self.identifier_preparer.illegal_initial_characters.add('_')
 
     def initialize(self, connection):
-        # the DefaultDialect issues some queries to test for unicode support in
-        # the resutls. etc. -> don't need any of that.
-        pass
+        # get lowest server version
+        self.server_version_info = \
+            self._get_server_version_info(connection)
+        # get default schema name
+        self.default_schema_name = \
+            self._get_default_schema_name(connection)
 
     def do_rollback(self, connection):
         # if any exception is raised by the dbapi, sqlalchemy by default
@@ -143,7 +145,38 @@ def connect(self, host=None, port=None, *args, **kwargs):
             return self.dbapi.connect(servers=server, **kwargs)
         return self.dbapi.connect(**kwargs)
 
+    def _get_default_schema_name(self, connection):
+        return 'doc'
+
+    def _get_server_version_info(self, connection):
+        return tuple(connection.connection.lowest_server_version.version)
+
     @classmethod
     def dbapi(cls):
         from crate import client
         return client
+
+    def has_schema(self, connection, schema):
+        return schema in self.get_schema_names(connection)
+
+    def has_table(self, connection, table_name, schema=None):
+        return table_name in self.get_table_names(connection, schema=schema)
+
+    @reflection.cache
+    def get_schema_names(self, connection, **kw):
+        cursor = connection.execute(
+            "select schema_name "
+            "from information_schema.schemata "
+            "order by schema_name asc"
+        )
+        return [row[0] for row in cursor.fetchall()]
+
+    @reflection.cache
+    def get_table_names(self, connection, schema=None, **kw):
+        cursor = connection.execute(
+            "select table_name from information_schema.tables "
+            "where schema_name = ? "
+            "order by table_name asc, schema_name asc",
+            [schema or self.default_schema_name]
+        )
+        return [row[0] for row in cursor.fetchall()]

src/crate/client/sqlalchemy/dialect.txt

@@ -0,0 +1,39 @@
+======================
+CrateDialect Internals
+======================
+
+The initialize method sets the default schema name and version info::
+
+    >>> connection = engine.connect()
+    >>> dialect = CrateDialect()
+    >>> dialect.initialize(connection)
+
+    >>> dialect.default_schema_name
+    'doc'
+
+    >>> dialect.server_version_info
+    (0, 46, 4)
+
+Check if table exists::
+
+    >>> dialect.has_table(connection, 'locations')
+    True
+
+List all tables::
+
+    >>> dialect.get_table_names(connection)
+    ['characters', 'locations']
+
+    >>> dialect.get_table_names(connection, schema='sys')
+    ['cluster', 'jobs', 'jobs_log', 'nodes', 'operations', 'operations_log', 'shards']
+
+Check if schema exists::
+
+    >>> dialect.has_schema(connection, 'doc')
+    True
+
+List all schemas::
+
+    >>> dialect.get_schema_names(connection)
+    [u'blob', u'doc', u'information_schema', u'sys']
+

src/crate/client/sqlalchemy/itests.txt

@@ -185,3 +185,4 @@ Reset the clima::
 
     >>> location.details
     []
+

src/crate/client/tests.py

@@ -39,6 +39,7 @@
 from crate.testing.layer import CrateLayer
 from crate.testing.tests import crate_path, docs_path
 from crate.client import connect
+from crate.client.sqlalchemy.dialect import CrateDialect
 
 from . import http
 from .test_cursor import CursorTest
@@ -158,6 +159,7 @@ class Location(Base):
     test.globs['Base'] = Base
     test.globs['session'] = session
     test.globs['Session'] = Session
+    test.globs['CrateDialect'] = CrateDialect
 
 
 _server = None
@@ -283,6 +285,7 @@ def test_suite():
 
     s = doctest.DocFileSuite(
         'sqlalchemy/itests.txt',
+        'sqlalchemy/dialect.txt',
         checker=checker,
         setUp=setUpCrateLayerAndSqlAlchemy,
         tearDown=tearDownWithCrateLayer,

src/crate/testing/tests.py

@@ -8,7 +8,7 @@ def docs_path(*parts):
 
 
 def crate_path(*parts):
-    return docs_path('..', '..', 'parts', 'crate', *parts)
+    return os.path.abspath(docs_path('..', '..', 'parts', 'crate', *parts))
 
 def public_ip():
     import socket