Add exists property to LDAPStorage.

CHANGES.rst

@@ -4,6 +4,9 @@ History
 1.0b7 (unreleased)
 ------------------
 
+- Add ``exists`` property to ``LDAPStorage``.
+  [rnix]
+
 - Add ``objectSid`` and ``objectGUID`` from Active Directory schema to
   ``properties.BINARY_DEFAULTS``.
   [rnix]

LICENSE.rst

@@ -1,7 +1,7 @@
 License
 =======
 
-Copyright (c) 2006-2016, BlueDynamics Alliance, Austria, Germany, Switzerland
+Copyright (c) 2006-2017, BlueDynamics Alliance, Austria, Germany, Switzerland
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without

README.rst

@@ -306,6 +306,13 @@ Every LDAP node has a DN and a RDN:
     >>> root.rdn_attr
     u'ou'
 
+Check whether created node exists in the database::
+
+.. code-block:: pycon
+
+    >>> root.exists
+    True
+
 Directory entry has no children yet:
 
 .. code-block:: pycon

src/node/ext/ldap/_node.py

@@ -433,6 +433,22 @@ def child_dn(self, key):
             return u','.join([decode(key), decode(self._dn)])
         return u','.join([decode(key), decode(self.name)])
 
+    @default
+    @property
+    def exists(self):
+        try:
+            res = self.ldap_session.search(
+                scope=BASE,
+                baseDN=self.DN.encode('utf-8'),
+                attrlist=['']
+            )
+            # this probably never happens
+            if len(res) != 1:
+                raise RuntimeError()
+            return True
+        except NO_SUCH_OBJECT:
+            return False
+
     @default
     def node_by_dn(self, dn, strict=False):
         """Return node from tree by DN.

src/node/ext/ldap/_node.rst

@@ -59,6 +59,15 @@ The non-unicode name got decoded::
     >>> root.rdn_attr
     u'dc'
 
+Check exists::
+
+    >>> root.exists
+    True
+
+    >>> inexistent = LDAPNode('dc=other-domain,dc=com', props)
+    >>> inexistent.exists
+    False
+
 LDAP attributes for DN are stored on ``attrs``::
 
     >>> root.attrs