[ANGULAR] Clarification on Task Start Date Changes in Bryntum Gantt

[m-yamagishi]

Hello Bryntum Support Team,

I need clarification on the behavior of task start date changes in Bryntum Gantt. Specifically, I would like to understand when and why task start dates can be changed and why sometimes they cannot be changed, depending on the order in which changes are made.

Here are some scenarios I've observed:
1. Changing the start date of task "1 Setup web server" to a past date:
* Sometimes, only "1.1 Data center server setup" moves.
* Other times, only "1.2 Install Apache" moves.

2. Changing the start date of "1.1 Data center server setup" to a past date:
* Sometimes, this causes "1 Setup web server" to move as well.

3. Changing the start date of "1.2 Install Apache" to a past date:
* Sometimes, this causes "1 Setup web server" to move.

I need to explain this behavior to end users, so it would be very helpful to know the following:
* Why does this happen?
* Under what conditions can these changes be made, and when can they not?
* How does the order of operations affect the ability to change start dates?

I tried the example provided in this link:
https://bryntum.com/products/gantt/examples/advanced/

Thank you for your assistance!

[arcady]

Hello,

The reason why the tasks are not falling back is they are pinned w/ "Start No Earlier Than" constraints on data loading stage.
There is a config on the project doing this: autoSetConstraints

And in that demo it's set to true:

    project : {
        autoSetConstraints : true,

You can change it to false to avoid this behaviour.

More info on tasks scheduling can found in this guide:
https://bryntum.com/products/gantt/docs/guide/engine/gantt_tasks_scheduling

Best regards,
Arcady

[m-yamagishi]

Hello Arcady,

Thank you for your quick response.
I understand the concept of "Start No Earlier Than". Which can be changed by dragging and dropping the tasks, the "START" date or the "CONSTRAINT DATE". Does it depend on the type of task? I believe tasks are green bars and blue bars. However, there is a possibility that my understanding is incorrect.

Best regards,

[arcady]

Hello,

Does it depend on the type of task? I believe tasks are green bars and blue bars. However, there is a possibility that my understanding is incorrect.

Yes both green and blue ones are tasks.
Blue ones are parent tasks (also know as summary or hammock tasks) that have children tasks. And green ones are regular tasks that have not children.

Yes both kind of tasks can have a constraint set.

Best regards,
Arcady

[m-yamagishi]

Hello Arcady,

Thank you for your helping. I just want to confirm which date will be set when the task is moved.

Best regards,

[arcady]

Hello,

Thank you for your helping. I just want to confirm which date will be set when the task is moved.

It depends on the task/project configuration. Details can be found in the guide I mentioned.

Best regards,
Arcady