Add support for parsing timestamp strings in data query results

This is added so doing data queries using runCommand works, but it should be avoided

Author: EnricSala

influxdb-client/SeriesResult.m

@@ -125,8 +125,16 @@
 
             % Check if the first field is the time
             if strcmp('time', fields{1})
-                timestamps = cell2mat(celled(:, 1));
-                time = TimeUtils.toDatetime(timestamps, epoch);
+                time_column = celled(:, 1);
+                if isnumeric(time_column{1})
+                    timestamps = cell2mat(time_column);
+                    time = TimeUtils.toDatetime(timestamps, epoch);
+                elseif ischar(time_column{1})
+                    parse = @TimeUtils.parseTimestamp;
+                    time = cellfun(parse, time_column);
+                else
+                    error('unsupported time type');
+                end
                 fields = fields(2:end);
                 celled = celled(:, 2:end);
             else

influxdb-client/TimeUtils.m

@@ -37,6 +37,37 @@
                 'ConvertFrom', 'posixtime', 'TimeZone', 'local');
         end
 
+        % Convert string timestamp to a datetime
+        function dtime = parseTimestamp(timestr)
+            switch length(timestr)
+                case 20
+                    format = 'yyyy-MM-dd''T''HH:mm:ss''Z''';
+                case 22
+                    format = 'yyyy-MM-dd''T''HH:mm:ss.S''Z''';
+                case 23
+                    format = 'yyyy-MM-dd''T''HH:mm:ss.SS''Z''';
+                case 24
+                    format = 'yyyy-MM-dd''T''HH:mm:ss.SSS''Z''';
+                case 25
+                    format = 'yyyy-MM-dd''T''HH:mm:ss.SSSS''Z''';
+                case 26
+                    format = 'yyyy-MM-dd''T''HH:mm:ss.SSSSS''Z''';
+                case 27
+                    format = 'yyyy-MM-dd''T''HH:mm:ss.SSSSSS''Z''';
+                case 28
+                    format = 'yyyy-MM-dd''T''HH:mm:ss.SSSSSSS''Z''';
+                case 29
+                    format = 'yyyy-MM-dd''T''HH:mm:ss.SSSSSSSS''Z''';
+                case 30
+                    format = 'yyyy-MM-dd''T''HH:mm:ss.SSSSSSSSS''Z''';
+                otherwise
+                    error('parseTimestamp:unknownFormat', ...
+                        'unknown timestamp format: %s', timestr);
+            end
+            dtime = datetime(timestr, 'InputFormat', format, 'TimeZone', 'UTC');
+            dtime.TimeZone = 'local';
+        end
+        
         % Validate a precision
         function validatePrecision(precision)
             assert(any(strcmp(precision, TimeUtils.PRECISIONS)), ...