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Adding/Updating/Deleting Links

In this chapter you'll learn how to do basic operations with dependency links: to create or delete a link, to dynamically update a link's property.

To add a new link to the Gantt chart, use the addLink method:

var linkId = gantt.addLink({
    id:1,
    source:1,
    target:2,
    type:"1"
});

To dynamically update a property of a link object, use the refreshLink method:

var links= gantt.config.links;
var link = gantt.getLink(1);//->{id:1,source:1, target:2, type:"1"}

if (link.type == links.finish_to_start){/*!*/ 
    link.type = links.finish_to_finish;/*!*/ 
    gantt.refreshLink(1); /*!*/ 
}/*!*/

Note, to update all links in the Gantt chart at once, use the refreshData method:

var links= gantt.config.links;

var link1 = gantt.getLink(1);//->{id:1,source:1, target:2, type:"1"}
var link2 = gantt.getLink(2);//->{id:2,source:4, target:5, type:"0"}

if (link1.type == links.finish_to_finish){/*!*/ 
    gantt.refreshData()/*!*/ 
}/*!*/
note

Note, all types of links' dependencies are stored in the links object

To delete a link, use the deleteLink method:

gantt.deleteLink(linkId);

To clear the Gantt chart from all tasks and links, call the clearAll method:

gantt.clearAll();

There is no built-in UI for the user to edit lag or any other properties of the link. So if you need some UI, you have to implement it manually.

A common approach presupposes following the steps below:

  • capture the onLinkDblClick event;
  • cancel the default handler;
  • display a popup from the event handler.

On the last step you can either use built-in popups or implement some custom solution.

Here is a sample code of the edit-lag popup implementation:

(function(){
    var modal;
    var editLinkId;

    function endPopup(){
        modal = null;
        editLinkId = null;
    }
    function cancelEditLink(){
        endPopup();
    }

    function deleteLink(){
        gantt.deleteLink(editLinkId);
        endPopup();
    }

    function saveLink(){
        var link = gantt.getLink(editLinkId);

        var lagValue = modal.querySelector(".lag-input").value;
        if(!isNaN(parseInt(lagValue, 10))){
            link.lag = parseInt(lagValue, 10);
        }

        gantt.updateLink(link.id);
        if(gantt.autoSchedule){
            gantt.autoSchedule(link.source);
        }
        endPopup();
    }
    gantt.attachEvent("onLinkDblClick", function(id,e){
        editLinkId = id;
        var link = gantt.getLink(id);
        var linkTitle = gantt.getTask(link.source).text + " -> " + 
            gantt.getTask(link.target).text;

        modal = gantt.modalbox({
            title: linkTitle,
            text: "<div>" +
                    "<label>Lag <input type='number' className='lag-input' /></label>" +
                "</div>",
            buttons: [
                {label:"Save", value:"save"},
                {label:"Cancel", value:"cancel"},
                {label:"Delete", value:"delete"}
            ],
            width: "500px",
            callback: function(result){
                switch(result){
                    case "save":
                        saveLink();
                        break;
                    case "cancel":
                        cancelEditLink();
                        break;

                    case "delete":
                        deleteLink();
                        break;
                }
            }
        });

        modal.querySelector(".lag-input").value = link.lag || 0;

        return false;
    });
})();

Related sample Edit-lag Popup