Implemented the abort_on_nonexistent parameter for sessions and disab…

…led not found exceptions by default

easysnmp/session.py

@@ -69,11 +69,18 @@ def validate_results(varlist):
     """
 
     for variable in varlist:
+        # Create a printable variable string for the error
+        varstr = variable.oid
+        if variable.oid_index:
+            varstr += ' with index {0}'.format(variable.oid_index)
+
         if variable.snmp_type == 'NOSUCHOBJECT':
-            raise EasySNMPNoSuchObjectError('no such object could be found')
-        if variable.value == 'NOSUCHINSTANCE':
+            raise EasySNMPNoSuchObjectError(
+                'no such object {0} could be found'.format(varstr)
+            )
+        if variable.snmp_type == 'NOSUCHINSTANCE':
             raise EasySNMPNoSuchInstanceError(
-                'no such instance could be found'
+                'no such instance {0} could be found'.format(varstr)
             )
 
 
@@ -149,6 +156,9 @@ class Session(object):
                           SNMP variables, when set to False this feature is
                           disabled and the entire get request will fail on
                           any NOSUCH error (applies to v1 only)
+    :param abort_on_nonexistent: raise an exception if no object or no
+                                 instance is found for the given oid and
+                                 oid index
     """
 
     def __init__(
@@ -161,7 +171,7 @@ def __init__(
         our_identity='', their_identity='', their_hostname='',
         trust_cert='', use_long_names=False, use_numeric=False,
         use_sprint_value=False, use_enums=False, best_guess=0,
-        retry_no_such=False
+        retry_no_such=False, abort_on_nonexistent=False
     ):
         # Validate and extract the remote port
         if ':' in hostname:
@@ -202,6 +212,7 @@ def __init__(
         self.use_enums = use_enums
         self.best_guess = best_guess
         self.retry_no_such = retry_no_such
+        self.abort_on_nonexistent = abort_on_nonexistent
 
         # The following variables are required for internal use as they are
         # passed to the C interface
@@ -304,7 +315,8 @@ def get(self, oids):
         interface.get(self, varlist)
 
         # Validate the variable list returned
-        validate_results(varlist)
+        if self.abort_on_nonexistent:
+            validate_results(varlist)
 
         # Return a list or single item depending on what was passed in
         return list(varlist) if is_list else varlist[0]
@@ -392,7 +404,8 @@ def get_next(self, oids):
         interface.getnext(self, varlist)
 
         # Validate the variable list returned
-        validate_results(varlist)
+        if self.abort_on_nonexistent:
+            validate_results(varlist)
 
         # Return a list or single item depending on what was passed in
         return list(varlist) if is_list else varlist[0]
@@ -427,7 +440,8 @@ def get_bulk(self, oids, non_repeaters, max_repetitions):
         interface.getbulk(self, non_repeaters, max_repetitions, varlist)
 
         # Validate the variable list returned
-        validate_results(varlist)
+        if self.abort_on_nonexistent:
+            validate_results(varlist)
 
         # Return a list of variables
         return varlist
@@ -453,7 +467,8 @@ def walk(self, oids='.1.3.6.1.2.1'):
         interface.walk(self, varlist)
 
         # Validate the variable list returned
-        validate_results(varlist)
+        if self.abort_on_nonexistent:
+            validate_results(varlist)
 
         # Return a list of variables
         return list(varlist)

easysnmp/variables.py

@@ -15,7 +15,9 @@ class SNMPVariable(object):
     :param value: the OID value
     :param snmp_type: the snmp_type of data contained in val (please see
                       http://www.net-snmp.org/wiki/index.php/TUT:snmpset#Data_Types
-                      for further information)
+                      for further information); in the case that an object
+                      or instance is not found, the type will be set to
+                      NOSUCHOBJECT and NOSUCHINSTANCE respectively
     """
 
     def __init__(self, oid=None, oid_index=None, value=None, snmp_type=None):

tests/test_easy.py

@@ -123,22 +123,43 @@ def test_snmp_get_unknown(sess_args):
     'sess_args', [sess_v1_args(), sess_v2_args(), sess_v3_args()]
 )
 def test_snmp_get_invalid_instance(sess_args):
+    # Sadly, SNMP v1 doesn't distuingish between an invalid instance and an
+    # invalid object ID, so it raises the same exception for both
+    res = snmp_get('sysContact.1', **sess_args)
+    if sess_args['version'] == 1:
+        res.snmp_type == 'NOSUCHOBJECT'
+    else:
+        res.snmp_type == 'NOSUCHINSTANCE'
+
+
+@pytest.mark.parametrize(
+    'sess_args', [sess_v1_args(), sess_v2_args(), sess_v3_args()]
+)
+def test_snmp_get_invalid_instance_with_abort_enabled(sess_args):
     # Sadly, SNMP v1 doesn't distuingish between an invalid instance and an
     # invalid object ID, so it raises the same exception for both
     if sess_args['version'] == 1:
         with pytest.raises(EasySNMPNoSuchObjectError):
-            snmp_get('sysContact.1', **sess_args)
+            snmp_get('sysContact.1', abort_on_nonexistent=True, **sess_args)
     else:
         with pytest.raises(EasySNMPNoSuchInstanceError):
-            snmp_get('sysContact.1', **sess_args)
+            snmp_get('sysContact.1', abort_on_nonexistent=True, **sess_args)
 
 
 @pytest.mark.parametrize(
     'sess_args', [sess_v1_args(), sess_v2_args(), sess_v3_args()]
 )
 def test_snmp_get_invalid_object(sess_args):
+    res = snmp_get('iso', **sess_args)
+    assert res.snmp_type == 'NOSUCHOBJECT'
+
+
+@pytest.mark.parametrize(
+    'sess_args', [sess_v1_args(), sess_v2_args(), sess_v3_args()]
+)
+def test_snmp_get_invalid_object_with_abort_enabled(sess_args):
     with pytest.raises(EasySNMPNoSuchObjectError):
-        snmp_get('iso', **sess_args)
+        snmp_get('iso', abort_on_nonexistent=True, **sess_args)
 
 
 @pytest.mark.parametrize(

tests/test_session.py

@@ -264,6 +264,18 @@ def test_session_get_bulk(sess):  # noqa
 def test_session_get_invalid_instance(sess):
     # Sadly, SNMP v1 doesn't distuingish between an invalid instance and an
     # invalid object ID, so it raises the same exception for both
+    res = sess.get('sysDescr.100')
+    if sess.version == 1:
+        assert res.snmp_type == 'NOSUCHOBJECT'
+    else:
+        assert res.snmp_type == 'NOSUCHINSTANCE'
+
+
+@pytest.mark.parametrize('sess', [sess_v1(), sess_v2(), sess_v3()])
+def test_session_get_invalid_instance_with_abort_enabled(sess):
+    # Sadly, SNMP v1 doesn't distuingish between an invalid instance and an
+    # invalid object ID, so it raises the same exception for both
+    sess.abort_on_nonexistent = True
     if sess.version == 1:
         with pytest.raises(EasySNMPNoSuchObjectError):
             sess.get('sysDescr.100')
@@ -274,6 +286,13 @@ def test_session_get_invalid_instance(sess):
 
 @pytest.mark.parametrize('sess', [sess_v1(), sess_v2(), sess_v3()])
 def test_session_get_invalid_object(sess):
+    res = sess.get('iso')
+    assert res.snmp_type == 'NOSUCHOBJECT'
+
+
+@pytest.mark.parametrize('sess', [sess_v1(), sess_v2(), sess_v3()])
+def test_session_get_invalid_object_with_abort_enabled(sess):
+    sess.abort_on_nonexistent = True
     with pytest.raises(EasySNMPNoSuchObjectError):
         sess.get('iso')