Step 4: Display Summaries

• Mar 19, 2025
• 3 minutes to read

You can display summary information about the groups of rows or individual data columns. Complete the following steps:

1. Process summaries in the virtual source.
2. Display summaries in the GridControl.

Explore the full source code in the following examples and demos:

Infinite Scrolling Source

View Example Run Demo

Paged Source

View Example Run Demo

Summary Types

The Issues Service allows you to obtain:

• The total count of rows.
• The last created DateTime object.

C#

public class IssuesSummaries {   
    public int Count { get; private set; }
    public DateTime? LastCreated { get; private set; }
}

Implementation Details

Process Summaries in the Virtual Source

1. Create a task that uses the IssuesService.GetSummariesAsync method to get summaries from the data source.

2. Use the Summaries property to get GridControl summary items.

3. Create a GetTotalSummaries command.

4. Get the list of data source summaries that correspond to GridControl summary items and assign the list to the Result property.

5. Bind the GetTotalSummaries command to the InfiniteAsyncSource.GetTotalSummariesCommand.

C#

[Command]
public void GetTotalSummaries(GetSummariesAsyncArgs args) {
    args.Result = GetTotalSummariesAsync(args);
}
static async Task<object[]> GetTotalSummariesAsync(GetSummariesAsyncArgs args) {
    var summaryValues = await IssuesService.GetSummariesAsync((IssueFilter)args.Filter);
    return args.Summaries.Select(x => {
        if(x.SummaryType == SummaryType.Count)
            return (object)summaryValues.Count;
        if(x.SummaryType == SummaryType.Max && x.PropertyName == "Created")
            return summaryValues.LastCreated;
        throw new InvalidOperationException();
    }).ToArray();
}

xml

<dxg:GridControl.ItemsSource>
    <dx:InfiniteAsyncSource ElementType="{x:Type local:IssueData}"
                            FetchRowsCommand="{Binding FetchIssuesCommand}"
                            GetUniqueValuesCommand="{Binding GetUniqueValuesCommand}"
                            GetTotalSummariesCommand="{Binding GetTotalSummariesCommand}"/>
</dxg:GridControl.ItemsSource>

Display Fixed Summary Panel

Enable the DataViewBase.ShowFixedTotalSummary property to display the Fixed Summary Panel:

xml

<dxg:GridControl.View>
    <dxg:TableView ShowFixedTotalSummary="True"/>
</dxg:GridControl.View>

Display Total Summaries

Specify the GridControl.TotalSummary property to display total summaries in the GridControl:

xml

<dxg:GridControl.TotalSummary>
    <dxg:GridSummaryItem SummaryType="Count" Alignment="Right"/>
    <dxg:GridSummaryItem SummaryType="Max" FieldName="Created" 
                         DisplayFormat="{}Last created: {0}" 
                         Alignment="Right"/>
</dxg:GridControl.TotalSummary>

Display Custom Summaries

The Issues Service can calculate the Median and StdDev values:

C#

public class IssuesSummaries {
    // ...
    public double VotesMedian { get; private set; }
    public double VotesStdDev { get; private set; }
}

1. Process summaries in the virtual source:

   C#

   [Command]
   public void GetTotalSummaries(GetSummariesAsyncArgs args) {
       args.Result = GetTotalSummariesAsync(args);
   }
   static async Task<object[]> GetTotalSummariesAsync(GetSummariesAsyncArgs args) {
       var summaryValues = await IssuesService.GetSummariesAsync((IssueFilter)args.Filter);
       return args.Summaries.Select(x => {
           if (x.SummaryType == SummaryType.Count)
               return (object)summaryValues.Count;
           if (x.SummaryType == SummaryType.Max && x.PropertyName == "Created")
               return summaryValues.LastCreated;
   
           // Custom Summaries
           if (x.SummaryType == SummaryType.Custom && x.PropertyName == "Votes") {
               var tag = x.Tag as string;
               if (tag == "Median")
                   return summaryValues.VotesMedian;
               if (tag == "StdDev")
                   return summaryValues.VotesStdDev;
           }
           throw new InvalidOperationException();
       }).ToArray();
   } 
   

2. Display summaries in the GridControl:

   xml

   <dxg:GridControl.TotalSummary>
       <dxg:GridSummaryItem SummaryType="Count" Alignment="Right"/>
       <dxg:GridSummaryItem SummaryType="Max" FieldName="Created" 
                            DisplayFormat="{}Last created: {0}" Alignment="Right"/>
       <!-- Custom Summaries -->
       <dxg:GridSummaryItem SummaryType="Custom" Tag="StdDev" FieldName="Votes" 
                            DisplayFormat="{}Votes StdDev={0}" Alignment="Right"/>
       <dxg:GridSummaryItem SummaryType="Custom" Tag="Median" FieldName="Votes" 
                            DisplayFormat="{}Votes Median={0}" Alignment="Right"/>
   </dxg:GridControl.TotalSummary> 
   

Continue

Tutorial 5: Enable Data Edit Operations