We've already discussed how the child nodes of a DragZone
must be registered in the Ext.dd.Registry
before they can be dragged around. This extra step can be a little painful, and we'll see ways around this later, but for now, let's concentrate on the advantages you get when a node is added to the Ext.dd.Registry
.
In our previous examples, we used the Ext.dd.Registry.register
method with a single parameter: the element to be registered. However, register
also takes a second, optional parameter that allows you to add an extra metadata object to the item being dragged around. This metadata can be leveraged in any way you see fit for your application, but a possible use would be to pass "compatibility" information to the drop event. Imagine you are producing an application that lets you assemble a "virtual outfit" by dragging and dropping items of clothing. We could use metadata to make sure that only items of clothing from the "summer" range can be combined, by including...