Allow to configure a database and precision epoch for data queries

Author: Enric Sala

influxdb-client/InfluxDB.m

@@ -53,12 +53,21 @@
         end
 
         % Execute a query string
-        function result = runQuery(obj, query)
+        function result = runQuery(obj, query, database, epoch)
+            if nargin < 3 || isempty(database)
+                database = obj.Database;
+            end
+            if nargin < 4 || isempty(epoch)
+                epoch = 'ms';
+            else
+                assert(any(strcmp(epoch, {'ns', 'u', 'ms', 's', 'm', 'h'})), ...
+                    'epoch:unknown', '"%s" is not a valid epoch', epoch);
+            end
             url = [obj.Url '/query'];
             opts = weboptions('Timeout', obj.ReadTimeout, ...
                 'Username', obj.User, 'Password', obj.Password);
-            response = webread(url, 'db', obj.Database, 'epoch', 'ms', 'q', query, opts);
-            result = QueryResult.from(response);
+            response = webread(url, 'db', database, 'epoch', epoch, 'q', query, opts);
+            result = QueryResult.from(response, epoch);
         end
 
         % Obtain a query builder

influxdb-client/QueryBuilder.m

@@ -2,6 +2,8 @@
 
     properties(Access = private)
         InfluxDB = []
+        Database = []
+        Epoch = []
         Series = {}
         Fields = {'*'}
         Tags = {}
@@ -29,6 +31,16 @@
             obj.InfluxDB = influxdb;
         end
 
+        % Configure the database
+        function obj = database(obj, database)
+            obj.Database = database;
+        end
+        
+        % Configure the epoch
+        function obj = epoch(obj, epoch)
+            obj.Epoch = epoch;
+        end
+        
         % Configure which series to query
         function obj = series(obj, varargin)
             if nargin > 2
@@ -205,7 +217,7 @@
             assert(~isempty(obj.InfluxDB), 'execute:clientNotSet', ...
                 'the influxdb client is not set for this builder');
             query = obj.build();
-            result = obj.InfluxDB.runQuery(query);
+            result = obj.InfluxDB.runQuery(query, obj.Database, obj.Epoch);
         end
     end
 

influxdb-client/QueryResult.m

@@ -49,10 +49,11 @@
 
     methods(Static)
         % Convert a response to objects
-        function objs = from(response)
+        function objs = from(response, epoch)
+            if nargin < 2, epoch = []; end
             assert(~isempty(response.results), ...
                 'from:empty', 'the response contains no results');
-            objs = arrayfun(@(x) QueryResult.wrap(x), ...
+            objs = arrayfun(@(x) QueryResult.wrap(x, epoch), ...
                 response.results, 'UniformOutput', false);
             nonempty = cellfun(@(x) ~isempty(x), objs);
             objs = cellfun(@(x) x, objs(nonempty));
@@ -61,12 +62,12 @@
 
     methods(Static, Access = private)
         % Wrap series results in a query result
-        function obj = wrap(result)
+        function obj = wrap(result, epoch)
             if isfield(result, 'error')
                 error('query:error', 'query error: %s', result.error);
             end
             if isfield(result, 'series')
-                series = arrayfun(@(x) SeriesResult.from(x), result.series);
+                series = arrayfun(@(x) SeriesResult.from(x, epoch), result.series);
                 obj = QueryResult(series);
             else
                 obj = [];

influxdb-client/SeriesResult.m

@@ -80,7 +80,7 @@
 
     methods(Static)
         % Convert a series result to an object
-        function obj = from(serie)
+        function obj = from(serie, epoch)
             fields = serie.columns;
             values = serie.values;
 
@@ -126,7 +126,7 @@
             % Check if the first field is the time
             if strcmp('time', fields{1})
                 timestamps = cell2mat(celled(:, 1));
-                time = SeriesResult.toDatetime(timestamps);
+                time = SeriesResult.toDatetime(timestamps, epoch);
                 fields = fields(2:end);
                 celled = celled(:, 2:end);
             else
@@ -166,11 +166,33 @@
     end
 
     methods(Static, Access = private)
-        % Convert a unix timestamp in millis to a datetime
-        function [time] = toDatetime(timestamp)
-            time = datetime(timestamp / 1000, ...
+        % Convert a unix timestamp to a datetime
+        function [time] = toDatetime(timestamp, epoch)
+            scale = SeriesResult.timeScale(epoch);
+            time = datetime(timestamp / scale, ...
                 'ConvertFrom', 'posixtime', 'TimeZone', 'local');
         end
+        
+        % Obtain the scale for an epoch
+        function scale = timeScale(epoch)
+            switch epoch
+                case 'ns'
+                    scale = 1000000000;
+                case 'u'
+                    scale = 1000000;
+                case 'ms'
+                    scale = 1000;
+                case 's'
+                    scale = 1;
+                case 'm'
+                    scale = 1 / 60;
+                case 'h'
+                    scale = 1 / 3600;
+                otherwise
+                    error('epoch:unknown', ...
+                        '"%s" is not a valid epoch', epoch);
+            end
+        end
     end
 
 end