- the dialects within sqlalchemy.databases become a setuptools

entry points. loading the built-in database dialects works the
same as always, but if none found will fall back to trying
pkg_resources to load an external module [ticket:521]

8 files changed, 86 insertions, 67 deletions

diff --git a/lib/sqlalchemy/databases/firebird.py b/lib/sqlalchemy/databases/firebird.py
index 2ab88101a..4695426eb 100644
--- a/lib/sqlalchemy/databases/firebird.py
+++ b/lib/sqlalchemy/databases/firebird.py
@@ -15,9 +15,6 @@ import sqlalchemy.ansisql as ansisql
 import sqlalchemy.types as sqltypes
 import sqlalchemy.exceptions as exceptions
 
-def dbapi():
-    import kinterbasdb
-    return kinterbasdb
 
 _initialized_kb = False
 
@@ -113,6 +110,11 @@ class FBDialect(ansisql.ANSIDialect):
         self.type_conv = type_conv
         self.concurrency_level= concurrency_level
 
+    def dbapi(cls):
+        import kinterbasdb
+        return kinterbasdb
+    dbapi = classmethod(dbapi)
+    
     def create_connect_args(self, url):
         opts = url.translate_connect_args(['host', 'database', 'user', 'password', 'port'])
         if opts.get('port'):
diff --git a/lib/sqlalchemy/databases/mssql.py b/lib/sqlalchemy/databases/mssql.py
index 41b51d12d..22fafad81 100644
--- a/lib/sqlalchemy/databases/mssql.py
+++ b/lib/sqlalchemy/databases/mssql.py
@@ -52,21 +52,6 @@ import sqlalchemy.ansisql as ansisql
 import sqlalchemy.types as sqltypes
 import sqlalchemy.exceptions as exceptions
 
-def dbapi(module_name=None):
-    if module_name:
-        try:
-            dialect_cls = dialect_mapping[module_name]
-            return dialect_cls.import_dbapi()
-        except KeyError:
-            raise exceptions.InvalidRequestError("Unsupported MSSQL module '%s' requested (must be adodbpi, pymssql or pyodbc)" % module_name)
-    else:
-        for dialect_cls in [MSSQLDialect_adodbapi, MSSQLDialect_pymssql, MSSQLDialect_pyodbc]:
-            try:
-                return dialect_cls.import_dbapi()
-            except ImportError, e:
-                pass
-        else:
-            raise ImportError('No DBAPI module detected for MSSQL - please install adodbapi, pymssql or pyodbc')
     
 class MSNumeric(sqltypes.Numeric):
     def convert_result_value(self, value, dialect):
@@ -331,7 +316,24 @@ class MSSQLDialect(ansisql.ANSIDialect):
         self.auto_identity_insert = auto_identity_insert
         self.text_as_varchar = False
         self.set_default_schema_name("dbo")
-            
+
+    def dbapi(cls, module_name=None):
+        if module_name:
+            try:
+                dialect_cls = dialect_mapping[module_name]
+                return dialect_cls.import_dbapi()
+            except KeyError:
+                raise exceptions.InvalidRequestError("Unsupported MSSQL module '%s' requested (must be adodbpi, pymssql or pyodbc)" % module_name)
+        else:
+            for dialect_cls in [MSSQLDialect_adodbapi, MSSQLDialect_pymssql, MSSQLDialect_pyodbc]:
+                try:
+                    return dialect_cls.import_dbapi()
+                except ImportError, e:
+                    pass
+            else:
+                raise ImportError('No DBAPI module detected for MSSQL - please install adodbapi, pymssql or pyodbc')
+    dbapi = classmethod(dbapi)
+    
     def create_connect_args(self, url):
         opts = url.translate_connect_args(['host', 'database', 'user', 'password', 'port'])
         opts.update(url.query)
diff --git a/lib/sqlalchemy/databases/mysql.py b/lib/sqlalchemy/databases/mysql.py
index d3a42ccdc..21f8bb398 100644
--- a/lib/sqlalchemy/databases/mysql.py
+++ b/lib/sqlalchemy/databases/mysql.py
@@ -12,9 +12,6 @@ import sqlalchemy.types as sqltypes
 import sqlalchemy.exceptions as exceptions
 from array import array
 
-def dbapi():
-    import MySQLdb as mysql
-    return mysql
 
 def kw_colspec(self, spec):
     if self.unsigned:
@@ -280,6 +277,11 @@ class MySQLDialect(ansisql.ANSIDialect):
     def __init__(self, **kwargs):
         ansisql.ANSIDialect.__init__(self, default_paramstyle='format', **kwargs)
 
+    def dbapi(cls):
+        import MySQLdb as mysql
+        return mysql
+    dbapi = classmethod(dbapi)
+    
     def create_connect_args(self, url):
         opts = url.translate_connect_args(['host', 'db', 'user', 'passwd', 'port'])
         opts.update(url.query)
diff --git a/lib/sqlalchemy/databases/oracle.py b/lib/sqlalchemy/databases/oracle.py
index fce59a072..f49f1d4c0 100644
--- a/lib/sqlalchemy/databases/oracle.py
+++ b/lib/sqlalchemy/databases/oracle.py
@@ -11,9 +11,6 @@ from sqlalchemy import util, sql, engine, schema, ansisql, exceptions, logging
 from sqlalchemy.engine import default, base
 import sqlalchemy.types as sqltypes
 
-def dbapi():
-    import cx_Oracle
-    return cx_Oracle
 
 
 class OracleNumeric(sqltypes.Numeric):
@@ -172,7 +169,12 @@ class OracleDialect(ansisql.ANSIDialect):
             self.ORACLE_BINARY_TYPES = [getattr(self.dbapi, k) for k in ["BFILE", "CLOB", "NCLOB", "BLOB", "LONG_BINARY", "LONG_STRING"] if hasattr(self.dbapi, k)]
         else:
             self.ORACLE_BINARY_TYPES = []
-            
+
+    def dbapi(cls):
+        import cx_Oracle
+        return cx_Oracle
+    dbapi = classmethod(dbapi)
+    
     def create_connect_args(self, url):
         if url.database:
             # if we have a database, then we have a remote host
diff --git a/lib/sqlalchemy/databases/postgres.py b/lib/sqlalchemy/databases/postgres.py
index a93ba200c..0eca18be3 100644
--- a/lib/sqlalchemy/databases/postgres.py
+++ b/lib/sqlalchemy/databases/postgres.py
@@ -16,15 +16,6 @@ try:
 except:
     mxDateTime = None
 
-def dbapi():
-    try:
-        import psycopg2 as psycopg
-    except ImportError, e:
-        try:
-            import psycopg
-        except ImportError, e2:
-            raise e
-    return psycopg
     
 class PGInet(sqltypes.TypeEngine):
     def get_col_spec(self):
@@ -258,6 +249,17 @@ class PGDialect(ansisql.ANSIDialect):
         self.use_information_schema = use_information_schema
         self.paramstyle = 'pyformat'
 
+    def dbapi(cls):
+        try:
+            import psycopg2 as psycopg
+        except ImportError, e:
+            try:
+                import psycopg
+            except ImportError, e2:
+                raise e
+        return psycopg
+    dbapi = classmethod(dbapi)
+    
     def create_connect_args(self, url):
         opts = url.translate_connect_args(['host', 'database', 'user', 'password', 'port'])
         if opts.has_key('port'):
diff --git a/lib/sqlalchemy/databases/sqlite.py b/lib/sqlalchemy/databases/sqlite.py
index 2b7e28dfb..0222496f8 100644
--- a/lib/sqlalchemy/databases/sqlite.py
+++ b/lib/sqlalchemy/databases/sqlite.py
@@ -12,18 +12,6 @@ import sqlalchemy.engine.default as default
 import sqlalchemy.types as sqltypes
 import datetime,time
 
-def dbapi():
-    try:
-        from pysqlite2 import dbapi2 as sqlite
-    except ImportError, e:
-        try:
-            from sqlite3 import dbapi2 as sqlite #try the 2.5+ stdlib name.
-        except ImportError:
-            try:
-                sqlite = __import__('sqlite') # skip ourselves
-            except ImportError:
-                raise e
-    return sqlite
     
 class SLNumeric(sqltypes.Numeric):
     def get_col_spec(self):
@@ -160,6 +148,20 @@ class SQLiteDialect(ansisql.ANSIDialect):
             return tuple([int(x) for x in num.split('.')])
         self.supports_cast = (self.dbapi is None or vers(self.dbapi.sqlite_version) >= vers("3.2.3"))
 
+    def dbapi(cls):
+        try:
+            from pysqlite2 import dbapi2 as sqlite
+        except ImportError, e:
+            try:
+                from sqlite3 import dbapi2 as sqlite #try the 2.5+ stdlib name.
+            except ImportError:
+                try:
+                    sqlite = __import__('sqlite') # skip ourselves
+                except ImportError:
+                    raise e
+        return sqlite
+    dbapi = classmethod(dbapi)
+
     def compiler(self, statement, bindparams, **kwargs):
         return SQLiteCompiler(self, statement, bindparams, **kwargs)
 
@@ -347,4 +349,4 @@ class SQLiteIdentifierPreparer(ansisql.ANSIIdentifierPreparer):
         super(SQLiteIdentifierPreparer, self).__init__(dialect, omit_schema=True)
 
 dialect = SQLiteDialect
-poolclass = pool.SingletonThreadPool
+dialect.poolclass = pool.SingletonThreadPool
diff --git a/lib/sqlalchemy/engine/strategies.py b/lib/sqlalchemy/engine/strategies.py
index ba9b0968a..ed31743d8 100644
--- a/lib/sqlalchemy/engine/strategies.py
+++ b/lib/sqlalchemy/engine/strategies.py
@@ -41,27 +41,26 @@ class DefaultEngineStrategy(EngineStrategy):
         # create url.URL object
         u = url.make_url(name_or_url)
 
-        # get module from sqlalchemy.databases
-        module = u.get_module()
+        dialect_cls = u.get_dialect()
 
         dialect_args = {}
         # consume dialect arguments from kwargs
-        for k in util.get_cls_kwargs(module.dialect):
+        for k in util.get_cls_kwargs(dialect_cls):
             if k in kwargs:
                 dialect_args[k] = kwargs.pop(k)
 
         dbapi = kwargs.pop('module', None)
         if dbapi is None:
             dbapi_args = {}
-            for k in util.get_func_kwargs(module.dbapi):
+            for k in util.get_func_kwargs(dialect_cls.dbapi):
                 if k in kwargs:
                     dbapi_args[k] = kwargs.pop(k)
-            dbapi = module.dbapi(**dbapi_args)
+            dbapi = dialect_cls.dbapi(**dbapi_args)
         
         dialect_args['dbapi'] = dbapi
         
         # create dialect
-        dialect = module.dialect(**dialect_args)
+        dialect = dialect_cls(**dialect_args)
 
         # assemble connection arguments
         (cargs, cparams) = dialect.create_connect_args(u)
@@ -77,7 +76,7 @@ class DefaultEngineStrategy(EngineStrategy):
                     raise exceptions.DBAPIError("Connection failed", e)
             creator = kwargs.pop('creator', connect)
 
-            poolclass = kwargs.pop('poolclass', getattr(module, 'poolclass', poollib.QueuePool))
+            poolclass = kwargs.pop('poolclass', getattr(dialect_cls, 'poolclass', poollib.QueuePool))
             pool_args = {}
 
             # consume pool arguments from kwargs, translating a few of the arguments
@@ -158,17 +157,16 @@ class MockEngineStrategy(EngineStrategy):
         # create url.URL object
         u = url.make_url(name_or_url)
 
-        # get module from sqlalchemy.databases
-        module = u.get_module()
+        dialect_cls = u.get_dialect()
 
         dialect_args = {}
         # consume dialect arguments from kwargs
-        for k in util.get_cls_kwargs(module.dialect):
+        for k in util.get_cls_kwargs(dialect_cls):
             if k in kwargs:
                 dialect_args[k] = kwargs.pop(k)
 
         # create dialect
-        dialect = module.dialect(**dialect_args)
+        dialect = dialect_cls(**dialect_args)
 
         return MockEngineStrategy.MockConnection(dialect, executor)
 
diff --git a/lib/sqlalchemy/engine/url.py b/lib/sqlalchemy/engine/url.py
index faa0ffc11..c5ad90ee9 100644
--- a/lib/sqlalchemy/engine/url.py
+++ b/lib/sqlalchemy/engine/url.py
@@ -69,19 +69,28 @@ class URL(object):
             s += '?' + "&".join(["%s=%s" % (k, self.query[k]) for k in keys])
         return s
 
-    def get_module(self):
-        """Return the SQLAlchemy database module corresponding to this URL's driver name."""
+    def get_dialect(self):
+        """Return the SQLAlchemy database dialect class corresponding to this URL's driver name."""
+        dialect=None
         if self.drivername == 'ansi':
             import sqlalchemy.ansisql
-            return sqlalchemy.ansisql
-            
+            return sqlalchemy.ansisql.dialect
+
         try:
-            return getattr(__import__('sqlalchemy.databases.%s' % self.drivername).databases, self.drivername)
+            module=getattr(__import__('sqlalchemy.databases.%s' % self.drivername).databases, self.drivername)
+            dialect=module.dialect
         except ImportError:
             if sys.exc_info()[2].tb_next is None:
-                raise exceptions.ArgumentError('unknown database %r' % self.drivername)
-            raise
-
+                import pkg_resources
+                for res in pkg_resources.iter_entry_points('sqlalchemy.databases'):
+                    if res.name==self.drivername:
+                        dialect=res.load()
+            else:
+               raise
+        if dialect is not None:
+            return dialect
+        raise ImportError('unknown database %r' % self.drivername) 
+  
     def translate_connect_args(self, names):
         """Translate this URL's attributes into a dictionary of connection arguments.