How to Update All Successor Tasks When Updating the Parent Task

Environment

Product

Progress® Telerik® UI for ASP.NET MVC Gantt

Description

In some scenarios the start of one task is dependent on the end of another task. In such a case, if the end of the initial task changes, the start of the dependent task should also change automatically. How can I achieve this?

Solution

1. Handle the e.Events(e=>e.Save()) event of the Gantt component.
2. Find the time gap between the previous and the new end time of the updated task.
3. Filter the dependencies of the updated tasks and update the start and end time accordignly.

@using Telerik.Scaffolders.Models.Gantt

<script>
    var data = [
        {
            id: 1,
            orderId: 0,
            parentId: null,
            title: "Task1",
            start: new Date("2014/6/17 9:00"),
            end: new Date("2014/6/17 10:00")
        },
        {
            id: 2,
            orderId: 1,
            parentId: null,
            title: "Task2",
            start: new Date("2014/6/17 9:40"),
            end: new Date("2014/6/17 11:00")
        },
        {
            id: 3,
            orderId: 2,
            parentId: null,
            title: "Task3",
            start: new Date("2014/6/17 11:00"),
            end: new Date("2014/6/17 12:30")
        },
        {
            id: 4,
            orderId: 3,
            parentId: null,
            title: "Task4",
            start: new Date("2014/6/17 9:00"),
            end: new Date("2014/6/17 11:00")
        },
        {
            id: 5,
            orderId: 4,
            parentId: null,
            title: "Task5",
            start: new Date("2014/6/17 11:00"),
            end: new Date("2014/6/17 12:00")
        },
        {
            id: 6,
            orderId: 5,
            parentId: null,
            title: "Task 6",
            start: new Date("2014/6/17 13:30"),
            end: new Date("2014/6/17 15:00")
        }
    ];

    var dependencies= [
        {
            id: 1,
            predecessorId: 1,
            successorId: 2,
            type: 1
        },
        {
            id: 2,
            predecessorId: 2,
            successorId: 3,
            type: 1
        },
        {
            id: 3,
            predecessorId: 4,
            successorId: 5,
            type: 1
        },
        {
            id: 4,
            predecessorId: 3,
            successorId: 6,
            type: 1
        },
    ];

</script>

@(Html.Kendo().Gantt<TaskModel, DependencyModel>()
    .Name("gantt")
        .Height(400)
        .DataSource("data")
        .DependenciesDataSource("dependencies")
        .Events(e => e.Save("ganttSave"))
    )

<script>
    function ganttSave(e) {
        var task = e.task;

        if (!e.values.end) {
            return;
        }

        var startDelta = e.values.end - e.task.end;

        moveTask(e.sender, task, startDelta)

        e.sender.dependencies.filter(null);
        e.sender.dataSource.sync();
    }

    function moveTask(gantt, task, startDelta) {

        var t = gantt.dependencies.filter({
            field: "predecessorId",
            operator: "equals",
            value: task.id
        });


        $(gantt.dependencies.view()).each(function (index, dependency) {

            var dependentTask = gantt.dataSource.get(dependency.successorId);
            var dependentTaskStart = dependentTask.get("start");
            var dependentTaskEnd = dependentTask.get("end");

            dependentTask.set("start", new Date(dependentTaskStart.getTime() + startDelta));
            dependentTask.set("end", new Date(dependentTaskEnd.getTime() + startDelta));

            gantt.dependencies.filter(null);

            var nextTask = gantt.dataSource.get(dependentTask.id);

            moveTask(gantt, nextTask, startDelta)

        });
    }
</script>