Data can be supplied from code by loading a dataset and registering it in place of the template's connections.

Load a dataset and register it.
var report = Stimulsoft.Report.StiReport.createNewDashboard();
report.loadFile("../dashboard/Dashboard.mrt");

var dataSet = new Stimulsoft.System.Data.DataSet("Demo");
dataSet.readJsonFile("../dashboard/Demo.json");

report.dictionary.databases.clear();
report.regData("Demo", "Demo", dataSet);

viewer.report = report;

How it works. The dashboard resolves its elements against the registered dataset, so one template works with any compatible JSON source.
На скриншоте ниже Вы можете увидеть результат выполнения данного кода:

Registering a Data for Dashboard Template