Handles REST responses when require ing datasource classes

scripts/lua/rest/v1/get/datasource/datasource.lua

@@ -0,0 +1,133 @@
+--
+-- (C) 2013-21 - ntop.org
+--
+
+local dirs = ntop.getDirs()
+package.path = dirs.installdir .. "/scripts/lua/modules/?.lua;" .. package.path
+package.path = dirs.installdir .. "/scripts/lua/modules/datasources/?.lua;" .. package.path
+
+local json = require "dkjson"
+local rest_utils = require "rest_utils"
+-- Import the classes library.
+local classes = require "classes"
+
+-- ##############################################
+
+local datasource = classes.class()
+
+-- ##############################################
+
+-- This is the base REST prefix for all the available datasources
+datasource.BASE_REST_PREFIX = "/lua/rest/v1/get/datasource/"
+
+-- ##############################################
+
+-- @brief Base class constructor
+function datasource:init()
+end
+
+-- ##############################################
+
+-- @brief Parses params
+-- @param params_table A table with submitted params
+-- @return True if parameters parsing is successful, false otherwise
+function datasource:read_params(params_table)
+   if not params_table then
+      self.parsed_params = nil
+      return false
+   end
+
+   self.parsed_params = {}
+   for _, param in pairs(self.meta.params or {}) do
+      local parsed_param = params_table[param]
+
+      -- Assumes all params mandatory and not empty
+      -- May override this behavior in subclasses
+      if isEmptyString(parsed_param) then
+	 -- Reset any possibly set param
+	 self.parsed_params = nil
+
+	 return false
+      end
+
+      self.parsed_params[param] = parsed_param
+   end
+
+   -- Ok, parsin has been successful
+   return true
+end
+
+-- ##############################################
+
+-- @brief Parses params submitted along with the REST endpoint request. If parsing fails, a REST error is sent.
+-- @param params_table A table with submitted params, either _POST or _GET
+-- @return True if parameters parsing is successful, false otherwise
+function datasource:_rest_read_params(params_table)
+   if not self:read_params(params_table) then
+      rest_utils.answer(rest_utils.consts.err.widgets_missing_datasource_params)
+      return false
+   end
+
+   return true
+end
+
+-- ##############################################
+
+-- @brief Send datasource data via REST
+function datasource:rest_send_response()
+   -- Make sure this is a direct REST request and not just a require() that needs this class
+   if not _SERVER -- Not executing a Lua script initiated from the web server (i.e., backend execution)
+   or not _SERVER["URI"] -- Cannot reliably determine if this is a REST request
+   or not _SERVER["URI"]:starts(datasource.BASE_REST_PREFIX) -- Web Lua script execution but not for this REST endpoint
+   then
+      -- Don't send any REST response
+      return
+   end
+
+   if not self:_rest_read_params(_POST) then
+      -- Params parsing has failed, error response already sent by the caller
+      return
+   end
+
+   self:fetch()
+
+   rest_utils.answer(
+      rest_utils.consts.success.ok,
+      self.datamodel_instance:get_data()
+   )
+end
+
+-- ##############################################
+
+-- @brief Deserializes REST endpoint response into an internal datamodel
+-- @param rest_response_data Response data as obtained from the REST call
+function datasource:deserialize(rest_response_data)
+   if rest_response_data and rest_response_data.RESPONSE_CODE == 200 then
+      local data = json.decode(rest_response_data.CONTENT)
+      local when = os.time()
+
+      if data and data.rc == rest_utils.consts.success.ok.rc then
+	 self.datamodel_instance = self.meta.datamodel:new(data.rsp.header)
+
+	 for _, row in ipairs(data.rsp.rows) do
+	    self.datamodel_instance:appendRow(when, data.rsp.header, row)
+	 end
+      end
+   end
+end
+
+-- ##############################################
+
+-- @brief Transform data according to the specified transformation
+-- @param data The data to be transformed
+-- @param transformation The transformation to be applied
+-- @return transformed data
+function datasource:transform(transformation)
+   return self.datamodel_instance:transform(transformation)
+end
+
+-- ##############################################
+
+return datasource
+
+-- ##############################################