Implementation of make_dsn in Python

This is equivalent to what proposed in #363, but with a much simpler
implementation.

lib/__init__.py

@@ -80,28 +80,9 @@ else:
     _ext.register_adapter(Decimal, Adapter)
     del Decimal, Adapter
 
-import re
 
-def _param_escape(s,
+def connect(dsn=None, connection_factory=None, cursor_factory=None,
-        re_escape=re.compile(r"([\\'])"),
+        async=False, **kwargs):
-        re_space=re.compile(r'\s')):
-    """
-    Apply the escaping rule required by PQconnectdb
-    """
-    if not s: return "''"
-
-    s = re_escape.sub(r'\\\1', s)
-    if re_space.search(s):
-        s = "'" + s + "'"
-
-    return s
-
-del re
-
-
-def connect(dsn=None,
-        database=None, user=None, password=None, host=None, port=None,
-        connection_factory=None, cursor_factory=None, async=False, **kwargs):
     """
     Create a new database connection.
 
@@ -115,7 +96,7 @@ def connect(dsn=None,
 
     The basic connection parameters are:
 
-    - *dbname*: the database name (only in dsn string)
+    - *dbname*: the database name
     - *database*: the database name (only as keyword argument)
     - *user*: user name used to authenticate
     - *password*: password used to authenticate
@@ -135,32 +116,10 @@ def connect(dsn=None,
     library: the list of supported parameters depends on the library version.
 
     """
-    items = []
+    if dsn is None and not kwargs:
-    if database is not None:
+        raise TypeError('missing dsn and no parameters')
-        items.append(('dbname', database))
-    if user is not None:
-        items.append(('user', user))
-    if password is not None:
-        items.append(('password', password))
-    if host is not None:
-        items.append(('host', host))
-    if port is not None:
-        items.append(('port', port))
-
-    items.extend([(k, v) for (k, v) in kwargs.iteritems() if v is not None])
-
-    if dsn is not None and items:
-        raise TypeError(
-            "'%s' is an invalid keyword argument when the dsn is specified"
-                % items[0][0])
-
-    if dsn is None:
-        if not items:
-            raise TypeError('missing dsn and no parameters')
-        else:
-            dsn = " ".join(["%s=%s" % (k, _param_escape(str(v)))
-                for (k, v) in items])
 
+    dsn = _ext.make_dsn(dsn, **kwargs)
     conn = _connect(dsn, connection_factory=connection_factory, async=async)
     if cursor_factory is not None:
         conn.cursor_factory = cursor_factory

lib/extensions.py

@@ -7,7 +7,7 @@ This module holds all the extensions to the DBAPI-2.0 provided by psycopg.
 - `lobject` -- the new-type inheritable large object class
 - `adapt()` -- exposes the PEP-246_ compatible adapting mechanism used
   by psycopg to adapt Python types to PostgreSQL ones
-  
+
 .. _PEP-246: http://www.python.org/peps/pep-0246.html
 """
 # psycopg/extensions.py - DBAPI-2.0 extensions specific to psycopg
@@ -32,6 +32,9 @@ This module holds all the extensions to the DBAPI-2.0 provided by psycopg.
 # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 # License for more details.
 
+import re as _re
+import sys as _sys
+
 from psycopg2._psycopg import UNICODE, INTEGER, LONGINTEGER, BOOLEAN, FLOAT
 from psycopg2._psycopg import TIME, DATE, INTERVAL, DECIMAL
 from psycopg2._psycopg import BINARYARRAY, BOOLEANARRAY, DATEARRAY, DATETIMEARRAY
@@ -56,7 +59,8 @@ try:
 except ImportError:
     pass
 
-from psycopg2._psycopg import adapt, adapters, encodings, connection, cursor, lobject, Xid, libpq_version, parse_dsn, quote_ident
+from psycopg2._psycopg import adapt, adapters, encodings, connection, cursor
+from psycopg2._psycopg import lobject, Xid, libpq_version, parse_dsn, quote_ident
 from psycopg2._psycopg import string_types, binary_types, new_type, new_array_type, register_type
 from psycopg2._psycopg import ISQLQuote, Notify, Diagnostics, Column
 
@@ -98,7 +102,6 @@ TRANSACTION_STATUS_INTRANS = 2
 TRANSACTION_STATUS_INERROR = 3
 TRANSACTION_STATUS_UNKNOWN = 4
 
-import sys as _sys
 
 # Return bytes from a string
 if _sys.version_info[0] < 3:
@@ -108,6 +111,7 @@ else:
     def b(s):
         return s.encode('utf8')
 
+
 def register_adapter(typ, callable):
     """Register 'callable' as an ISQLQuote adapter for type 'typ'."""
     adapters[(typ, ISQLQuote)] = callable
@@ -151,6 +155,41 @@ class NoneAdapter(object):
         return _null
 
 
+def make_dsn(dsn=None, **kwargs):
+    """Convert a set of keywords into a connection strings."""
+    # Override the dsn with the parameters
+    if 'database' in kwargs:
+        if 'dbname' in kwargs:
+            raise TypeError(
+                "you can't specify both 'database' and 'dbname' arguments")
+        kwargs['dbname'] = kwargs.pop('database')
+
+    if dsn is not None:
+        tmp = parse_dsn(dsn)
+        tmp.update(kwargs)
+        kwargs = tmp
+
+    dsn = " ".join(["%s=%s" % (k, _param_escape(str(v)))
+        for (k, v) in kwargs.iteritems()])
+    return dsn
+
+
+def _param_escape(s,
+        re_escape=_re.compile(r"([\\'])"),
+        re_space=_re.compile(r'\s')):
+    """
+    Apply the escaping rule required by PQconnectdb
+    """
+    if not s:
+        return "''"
+
+    s = re_escape.sub(r'\\\1', s)
+    if re_space.search(s):
+        s = "'" + s + "'"
+
+    return s
+
+
 # Create default json typecasters for PostgreSQL 9.2 oids
 from psycopg2._json import register_default_json, register_default_jsonb
 

tests/test_module.py

@@ -43,6 +43,9 @@ class ConnectTestCase(unittest.TestCase):
     def tearDown(self):
         psycopg2._connect = self._connect_orig
 
+    def assertDsnEqual(self, dsn1, dsn2):
+        self.assertEqual(set(dsn1.split()), set(dsn2.split()))
+
     def test_there_has_to_be_something(self):
         self.assertRaises(TypeError, psycopg2.connect)
         self.assertRaises(TypeError, psycopg2.connect,
@@ -57,8 +60,8 @@ class ConnectTestCase(unittest.TestCase):
         self.assertEqual(self.args[2], False)
 
     def test_dsn(self):
-        psycopg2.connect('dbname=blah x=y')
+        psycopg2.connect('dbname=blah application_name=y')
-        self.assertEqual(self.args[0], 'dbname=blah x=y')
+        self.assertDsnEqual(self.args[0], 'dbname=blah application_name=y')
         self.assertEqual(self.args[1], None)
         self.assertEqual(self.args[2], False)
 
@@ -90,30 +93,30 @@ class ConnectTestCase(unittest.TestCase):
         def f(dsn, async=False):
             pass
 
-        psycopg2.connect(database='foo', bar='baz', connection_factory=f)
+        psycopg2.connect(database='foo', application_name='baz', connection_factory=f)
-        self.assertEqual(self.args[0], 'dbname=foo bar=baz')
+        self.assertDsnEqual(self.args[0], 'dbname=foo application_name=baz')
         self.assertEqual(self.args[1], f)
         self.assertEqual(self.args[2], False)
 
-        psycopg2.connect("dbname=foo bar=baz", connection_factory=f)
+        psycopg2.connect("dbname=foo application_name=baz", connection_factory=f)
-        self.assertEqual(self.args[0], 'dbname=foo bar=baz')
+        self.assertDsnEqual(self.args[0], 'dbname=foo application_name=baz')
         self.assertEqual(self.args[1], f)
         self.assertEqual(self.args[2], False)
 
     def test_async(self):
-        psycopg2.connect(database='foo', bar='baz', async=1)
+        psycopg2.connect(database='foo', application_name='baz', async=1)
-        self.assertEqual(self.args[0], 'dbname=foo bar=baz')
+        self.assertDsnEqual(self.args[0], 'dbname=foo application_name=baz')
         self.assertEqual(self.args[1], None)
         self.assert_(self.args[2])
 
-        psycopg2.connect("dbname=foo bar=baz", async=True)
+        psycopg2.connect("dbname=foo application_name=baz", async=True)
-        self.assertEqual(self.args[0], 'dbname=foo bar=baz')
+        self.assertDsnEqual(self.args[0], 'dbname=foo application_name=baz')
         self.assertEqual(self.args[1], None)
         self.assert_(self.args[2])
 
     def test_empty_param(self):
         psycopg2.connect(database='sony', password='')
-        self.assertEqual(self.args[0], "dbname=sony password=''")
+        self.assertDsnEqual(self.args[0], "dbname=sony password=''")
 
     def test_escape(self):
         psycopg2.connect(database='hello world')
@@ -131,13 +134,12 @@ class ConnectTestCase(unittest.TestCase):
         psycopg2.connect(database=r"\every thing'")
         self.assertEqual(self.args[0], r"dbname='\\every thing\''")
 
-    def test_no_kwargs_swallow(self):
+    def test_params_merging(self):
-        self.assertRaises(TypeError,
+        psycopg2.connect('dbname=foo', database='bar')
-            psycopg2.connect, 'dbname=foo', database='foo')
+        self.assertEqual(self.args[0], 'dbname=bar')
-        self.assertRaises(TypeError,
+
-            psycopg2.connect, 'dbname=foo', user='postgres')
+        psycopg2.connect('dbname=foo', user='postgres')
-        self.assertRaises(TypeError,
+        self.assertDsnEqual(self.args[0], 'dbname=foo user=postgres')
-            psycopg2.connect, 'dbname=foo', no_such_param='meh')
 
 
 class ExceptionsTestCase(ConnectingTestCase):