Date Header Format

You can set a date format to the timeline major and minor slot headers.

To set the desired date format, use the parent tag of each view in the timeline.

All parameters are of type string.

GanttViews	Major slot header	Minor slot header
DayView	DayHeaderDateFormat	TimeHeaderDateFormat
WeekView	WeekHeaderDateFormat	DayHeaderDateFormat
MonthView	MonthHeaderDateFormat	WeekHeaderDateFormat
YearView	YearHeaderDateFormat	MonthHeaderDateFormat

Example

@* Format the dates in the Gantt Timeline by using the corresponding view parameter *@

<TelerikGantt Data="@Data"
              Width="1200px"
              Height="600px"
              IdField="Id"
              ParentIdField="ParentId"
              OnUpdate="@UpdateItem"
              OnDelete="@DeleteItem"
              OnCreate="@CreateItem">
    <GanttToolBarTemplate>
        <GanttCommandButton Command="Add" Icon="@SvgIcon.Plus">Add</GanttCommandButton>
    </GanttToolBarTemplate>
    <GanttViews>
        <GanttDayView 
            DayHeaderDateFormat="Date: {0:MMMM dd}" 
            TimeHeaderDateFormat="{0:HH:mm}">
        </GanttDayView>
        <GanttWeekView 
            WeekHeaderDateFormat="{0: MMMM dd}" 
            DayHeaderDateFormat="{0:dddd}">
        </GanttWeekView>
        <GanttMonthView 
            MonthHeaderDateFormat="Month: {0:MMMM}" 
            WeekHeaderDateFormat="{0:dd}">
        </GanttMonthView>
        <GanttYearView 
            YearHeaderDateFormat="Year: {0:yyyy}" 
            MonthHeaderDateFormat="{0:MMM}">
        </GanttYearView>
    </GanttViews>
    <GanttColumns>
        <GanttColumn Field="Id"
                     Visible="false">
        </GanttColumn>
        <GanttColumn Field="Title"
                     Expandable="true"
                     Width="160px"
                     Title="Task Title" >
        </GanttColumn>
        <GanttColumn Field="PercentComplete"
                     Width="60px">
        </GanttColumn>
        <GanttColumn Field="Start"
                     Width="100px"
                     TextAlign="@ColumnTextAlign.Right">
        </GanttColumn>
        <GanttColumn Field="End"
                     DisplayFormat="End: {0:d}"
                     Width="100px">
        </GanttColumn>
        <GanttCommandColumn>
            <GanttCommandButton Command="Add" Icon="@SvgIcon.Plus"></GanttCommandButton>
            <GanttCommandButton Command="Delete" Icon="@SvgIcon.Trash"></GanttCommandButton>
        </GanttCommandColumn>
    </GanttColumns>
</TelerikGantt>

@code {
    public DateTime SelectedDate { get; set; } = new DateTime(2019, 11, 11, 6, 0, 0);

    class FlatModel
    {
        public int Id { get; set; }
        public int? ParentId { get; set; }
        public string Title { get; set; }
        public double PercentComplete { get; set; }
        public DateTime Start { get; set; }
        public DateTime End { get; set; }
    }

    public int LastId { get; set; } = 1;
    List<FlatModel> Data { get; set; }

    protected override void OnInitialized()
    {
        Data = new List<FlatModel>();
        var random = new Random();

        for (int i = 1; i < 6; i++)
        {
            var newItem = new FlatModel()
            {
                Id = LastId,
                Title = "Employee  " + i.ToString(),
                Start = new DateTime(2020, 12, 6 + i),
                End = new DateTime(2020, 12, 11 + i),
                PercentComplete = Math.Round(random.NextDouble(), 2)
            };

            Data.Add(newItem);
            var parentId = LastId;
            LastId++;

            for (int j = 0; j < 5; j++)
            {
                Data.Add(new FlatModel()
                {
                    Id = LastId,
                    ParentId = parentId,
                    Title = "    Employee " + i + " : " + j.ToString(),
                    Start = new DateTime(2020, 12, 6 + i + j),
                    End = new DateTime(2020, 12, 7 + i + j),
                    PercentComplete = Math.Round(random.NextDouble(), 2)
                });

                LastId++;
            }
        }

        base.OnInitialized();
    }

    private async Task CreateItem(GanttCreateEventArgs args)
    {
        var argsItem = args.Item as FlatModel;

        argsItem.Id = LastId++;

        if (args.ParentItem != null)
        {
            var parent = (FlatModel)args.ParentItem;

            argsItem.ParentId = parent.Id;
        }

        Data.Insert(0, argsItem);

        CalculateParentPercentRecursive(argsItem);
        CalculateParentRangeRecursive(argsItem);
    }

    private async Task UpdateItem(GanttUpdateEventArgs args)
    {
        var item = args.Item as FlatModel;

        var foundItem = Data.FirstOrDefault(i => i.Id.Equals(item.Id));

        if (foundItem != null)
        {
            var startOffset = item.Start - foundItem.Start;
            if (startOffset != TimeSpan.Zero)
            {
                MoveChildrenRecursive(foundItem, startOffset);
            }

            foundItem.Title = item.Title;
            foundItem.Start = item.Start;
            foundItem.End = item.End;
            foundItem.PercentComplete = item.PercentComplete;
        }

        CalculateParentPercentRecursive(foundItem);
        CalculateParentRangeRecursive(foundItem);
    }

    private async Task DeleteItem(GanttDeleteEventArgs args)
    {
        var item = Data.FirstOrDefault(i => i.Id.Equals((args.Item as FlatModel).Id));

        RemoveChildRecursive(item);

        CalculateParentPercentRecursive(item);
        CalculateParentRangeRecursive(item);
    }

    public void OnItemExpand(GanttExpandEventArgs args)
    {
        var item = args.Item as FlatModel;

    }

    private void RemoveChildRecursive(FlatModel item)
    {
        var children = GetChildren(item).ToList();

        foreach (var child in children)
        {
            RemoveChildRecursive(child);
        }

        Data.Remove(item);
    }

    private void CalculateParentPercentRecursive(FlatModel item)
    {
        if (item.ParentId != null)
        {
            var parent = GetParent(item);

            var children = GetChildren(parent);

            if (children.Any())
            {
                parent.PercentComplete = children.Average(i => i.PercentComplete);

                CalculateParentPercentRecursive(parent);
            }
        }
    }

    private void CalculateParentRangeRecursive(FlatModel item)
    {
        if (item.ParentId != null)
        {
            var parent = GetParent(item);

            var children = GetChildren(parent);

            if (children.Any())
            {
                parent.Start = children.Min(i => i.Start);
                parent.End = children.Max(i => i.End);

                CalculateParentRangeRecursive(parent);
            }
        }
    }

    private void MoveChildrenRecursive(FlatModel item, TimeSpan offset)
    {
        var children = GetChildren(item);

        foreach (var child in children)
        {
            child.Start = child.Start.Add(offset);
            child.End = child.End.Add(offset);

            MoveChildrenRecursive(child, offset);
        }
    }

    private FlatModel GetParent(FlatModel item)
    {
        return Data.FirstOrDefault(i => i.Id.Equals(item.ParentId));
    }

    private IEnumerable<FlatModel> GetChildren(FlatModel item)
    {
        return Data.Where(i => item.Id.Equals(i.ParentId));
    }
}