Step 2: Enable Sort Operations

• Aug 17, 2022
• 2 minutes to read

This step describes how to allow users to sort rows:

• Implement sort operations in the virtual source.
• Enable these operations in the GridControl.

View Example: Data Grid - Bind to InfiniteAsyncSource

Sort Orders

The Issues Service allows you to apply the following sort orders:

• Default - records are shown from newest to oldest
• Created Date in Descending order
• Votes in any order

C#

public enum IssueSortOrder {
    Default,
    CreatedDescending,
    VotesAscending,
    VotesDescending
}

The Step 1: Fetch Data topic demonstrates how to fetch rows with the default sort order:

C#

public MainPage() {
    // ... 
    source.FetchRows += (o, e) => {
        e.Result = FetchRowsAsync(e);
    };
}
static async Task<FetchRowsResult> FetchRowsAsync(FetchRowsAsyncEventArgs e) {
    var take = 30;
    var issues = await IssuesService.GetIssuesAsync(
        skip: e.Skip,
        take: take,
        sortOrder: IssueSortOrder.Default,
        filter: null);
    return new FetchRowsResult(issues, hasMoreRows: issues.Length == take);
}

Allow Users to Sort Rows

1. Implement sort operations in the virtual source:

   • Use the FetchEventArgsBase.SortOrder property to get the GridControl‘s sort options.

   • Parse these sort options and return a sort order. The InfiniteAsyncSource.FetchRows event handler uses this sort order when the GridControl fetches rows.

   C#

   static IssueSortOrder GetIssueSortOrder(SortDefinition[] sortOrder) {
       if (sortOrder.Length > 0) {
           var sort = sortOrder.Single();
           if (sort.PropertyName == "Created") {
               if (sort.Direction != ListSortDirection.Descending)
                   throw new InvalidOperationException();
               return IssueSortOrder.CreatedDescending;
           }
           if (sort.PropertyName == "Votes") {
               return sort.Direction == ListSortDirection.Ascending
                   ? IssueSortOrder.VotesAscending
                   : IssueSortOrder.VotesDescending;
           }
       }
       return IssueSortOrder.Default;
   }
   
   static async Task<FetchRowsResult> FetchRowsAsync(FetchRowsAsyncEventArgs e) {
       IssueSortOrder sortOrder = GetIssueSortOrder(e.SortOrder);
       var take = 30;
       var issues = await IssuesService.GetIssuesAsync(
           skip: e.Skip,
           take: take,
           sortOrder: sortOrder,
           filter: null);
       return new FetchRowsResult(issues, hasMoreRows: issues.Length == take);
   }
   

2. Allow users to sort GridControl rows by the Votes and Created columns. Set the ColumnBase.AllowSorting property to true for these columns:

   XAML

   <dxg:GridDateColumn FieldName="Created" AllowSorting="True"/>
   <dxg:GridTextColumn FieldName="Votes" AllowSorting="True"/>
   

Continue or Review

• Proceed to Step 3 - Enable Filter Operations.
• Review Step 1 - Fetch Data.