This sample demonstrates aggregate functionality of the Tree Grid. In this sample, the aggregate value for the columns “Total Units” and “Unit Weight” is displayed in column footer and provide an option to show child summary.
          The Tree Grid supports aggregates which will be displayed at the
          footer and every hierarchy level. The aggregate configurations can be
          provided by the  aggregates property.
        
The built-in aggregates are,
Sum
          Average
          Min
          Max
          Count
          TrueCount
          FalseCount
          Custom - Requires the customAggregate{" "}
            property to perform aggregation. The custom aggregate value can be
            accessed inside template using the key ${"custom"}
          
          In this demo, the footerTemplate property is used to
          display three different aggregates in the Tree Grid footer.
        
(${"Min"}).
          (${"Max"}).
          
          The template expression should be provided inside{" "}
          ${"..."} the interpolation syntax.
        
Additionally, the Tree Grid supports client-side exporting to Excel, PDF, and CSV formats. In this demo, for the toolbar items of exporting, actions are defined in the toolbarClick event to export the Tree Grid data using the excelExport, pdfExport, and csvExport methods.
Injecting Module:
          Tree Grid features are segregated into individual feature-wise
          modules. To use aggregate feature, we need to inject{" "}
          Aggregate module into the services.
        
More information about aggregate can be found in this documentation section.