When I use gantt.updateTask, it does not update links

Gantt
#1

https://snippet.dhtmlx.com/xi9e26dt

Hello Team,

When I use gantt.updateTask to update the start_date, the dependent tasks are not updated. In my snippet link, you can see that I’m calling gantt.updateTask for Task #1.

This is unlike when I use drag-and-drop. If I drag Task 1 to to another day in the future, the other tasks are automatically updated according to the link type.

Can you please let me know how to fix this issue? I want to be able to call gantt.updateTask and have the other tasks and links update accordingly.

Thanks!

#2

Hello,
If you update the task dates via the Gantt API, you need to manually call the autoSchedule method, and this is expected behavior:
https://docs.dhtmlx.com/gantt/api__gantt_autoschedule.html

1 Like
#3

Thank you Ramil. I knew it was definitely me that was missing something - this library is so robust :slight_smile:

If I change the duration and the start_date, how do I handle the end date?

Would I need to use gantt.calculateEndDate like this - DHTMLX Snippet Tool

Just want to double check. Thanks!

#4

Hello,
Thank you for the positive feedback!

The end_date property has a higher priority over the duration parameter. So, if you only update the duration parameter, it won’t change anything. If you update it with the start_date parameter, you will resize the task. So, yes, you need to manually update the end_date parameter by using the calculateEndDate method. If a task has a custom calendar, you also need to specify the task object as the third parameter:

task1.end_date = gantt.calculateEndDate({start_date: task1.start_date, duration: task1.duration, task: task1});

https://docs.dhtmlx.com/gantt/api__gantt_calculateenddate.html#:~:text=task%20-%20(object)%20optional%2C%20the%20object%20of%20the%20task%20the%20duration%20of%20which%20should%20be%20calculated

Also, it is not necessary to update a task by using the state approach (when you specify the task object as a second argument). You can update the task properties, then only specify the task’s ID in the updateTask method:

const task1 = gantt.getTask("1");
task1.start_date = new Date(2025, 3, 5);
task1.duration = 2;
task1.end_date = gantt.calculateEndDate({start_date: task1.start_date, duration: task1.duration});
gantt.updateTask(task1.id)
gantt.autoSchedule()

// or
const task1 = gantt.getTask("1");
const updatedParams = {
    start_date: new Date(2025, 3, 5),
    duration: 2,
    end_date: gantt.calculateEndDate({start_date: task1.start_date, duration: task1.duration})
}
gantt.mixin(task1, updatedParams, true)
gantt.updateTask(task1.id)
gantt.autoSchedule()