How to extend data copying in drag-and-drop?

Question

I have the following scenario: a list and a datatable both have the DnD feature enabled. The IDs of records is a part of visible data, but when I try to place items with equal IDs into one view, id becomes a randomly-generated one. As I want to perform a copy operation for data items, here's a question: how to prevent copying of items that already exists in the target datatable?

Here's my code https://jsfiddle.net/gL72d02c/

Copying implemented according to the sample in documentation, i.e.

$$("view").attachEvent("onBeforeDrop", function(context, ev){
    for (var i=0; i< context.source.length; i++){
        context.from.copy(context.source[i],context.start,this,webix.uid());
    }
    return false;
});

Answer 1

您需要做的就是检查目标小部件中是否有此类ID exists（文档）。即：

$$("petTable").attachEvent("onBeforeDrop", function(context, ev){  
    for (var i=0; i< context.source.length; i++){
        if (this.exists(context.source[i]))
            return false;
        context.from.copy(context.source[i],context.start,this,webix.uid());
    }
    return false;
});