[configdb]: add mod_entry, rename set_config to mod_config (sonic-net#25

)

* [configdb]: add mod_entry, rename set_config to mod_config

mod_entry will not delete extra data in the db.

change the set_config to mod_config so that mod_config does not
delete extra data in the db

src/swsssdk/configdb.py

@@ -5,7 +5,7 @@
  # Write to config DB
  config_db = ConfigDBConnector()
  config_db.connect()
- config_db.set_entry('BGP_NEIGHBOR', '10.0.0.1', {
+ config_db.mod_entry('BGP_NEIGHBOR', '10.0.0.1', {
  'admin_status': state
  })
 
@@ -144,6 +144,7 @@ def deserialize_key(key):
 
  def set_entry(self, table, key, data):
  """Write a table entry to config db.
+ Remove extra fields in the db which are not in the data.
  Args:
  table: Table name.
  key: Key of table entry, or a tuple of keys if it is a multi-key table.
@@ -164,6 +165,23 @@ def set_entry(self, table, key, data):
  k = k + '@'
  client.hdel(_hash, self.serialize_key(k))
 
+ def mod_entry(self, table, key, data):
+ """Modify a table entry to config db.
+ Args:
+ table: Table name.
+ key: Key of table entry, or a tuple of keys if it is a multi-key table.
+ data: Table row data in a form of dictionary {'column_key': 'value', ...}.
+ Pass {} as data will create an entry with no column if not already existed.
+ Pass None as data will delete the entry.
+ """
+ key = self.serialize_key(key)
+ client = self.redis_clients[self.CONFIG_DB]
+ _hash = '{}{}{}'.format(table.upper(), self.TABLE_NAME_SEPARATOR, key)
+ if data == None:
+ client.delete(_hash)
+ else:
+ client.hmset(_hash, self.__typed_to_raw(data))
+
  def get_entry(self, table, key):
  """Read a table entry from config db.
  Args:
@@ -202,8 +220,9 @@ def get_table(self, table):
  pass #Ignore non table-formated redis entries
  return data
 
- def set_config(self, data):
- """Write multiple tables into config db. 
+ def mod_config(self, data):
+ """Write multiple tables into config db.
+ Extra entries/fields in the db which are not in the data are kept.
  Args:
  data: config data in a dictionary form
  { 
@@ -215,7 +234,7 @@ def set_config(self, data):
  for table_name in data:
  table_data = data[table_name]
  for key in table_data:
- self.set_entry(table_name, key, table_data[key])
+ self.mod_entry(table_name, key, table_data[key])
 
  def get_config(self):
  """Read all config data.