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DataSource.FetchTimeRegions Event

Allows you to load time regions only for the specified date range.

Namespace: DevExpress.Xpf.Scheduling

Assembly: DevExpress.Xpf.Scheduling.v21.2.dll

Declaration

public event FetchDataEventHandler FetchTimeRegions

Event Data

The FetchTimeRegions event's data class is FetchDataEventArgs. The following properties provide information specific to this event:

Property Description
Ids Returns the identifiers of scheduler items that have been reloaded by the ReloadAppointments/ReloadTimeRegions methods.
Interval Returns the time range for which to fetch the scheduler items.
Result Specifies the list of scheduler items to load from the data source.

The event data class exposes the following methods:

Method Description
GetFetchExpression<T>() Generates an expression that you can use to obtain appointments from the data source.

Remarks

Specify TimeRegionMappings.QueryStart and TimeRegionMappings.QueryEnd mappings to handle the FetchTimeRegions event.

These mappings allow you to calculate the correct interval that is used in a SELECT query when you handle the FetchTimeRegions event. The use of the TimeRegionMappings.Start and TimeRegionMappings.End properties is not recommended in this scenario because such an interval may not include time region patterns and the corresponding exceptions.

The example below illustrates how to fetch time regions from a DbContext source. The FetchMode property is set to Bound.

public class SchedulingDataContext : DbContext {
    public SchedulingDataContext() : base(CreateConnection(), true) { }
    static DbConnection CreateConnection() {
        //...
    }
    public DbSet<TimeRegionEntity> TimeRegionEntities { get; set; }

    //...
}
private void dataSource_FetchTimeRegions(object sender, DevExpress.Xpf.Scheduling.FetchDataEventArgs e) {
    using (var dbContext = new SchedulingDataContext()) {
        e.Result = dbContext.TimeRegionEntities
            .Where(x => x.QueryStart <= e.Interval.End
                && x.QueryEnd >= e.Interval.Start)
            .ToArray();
    }
}

The FetchRange property specifies the time interval for which to fetch the time regions. FetchTimeRegion loads items for the SchedulerControl.VisibleIntervals extended up to the FetchRange.

Refer to the Load Data on Demand topic for more information.

See Also