Dynamically loading tree nodes

Enterprise applications usually have data sets that prohibit the loading of the full tree in a single JSON request. Large trees can be configured to load children on a per node basis by expanding levels on demand. A few minor changes to our code can allow us to implement this dynamic loading of node children.

When a node is expanded, the tree store proxy submits a request that contains a node parameter with the ID of the node being expanded. The URL submitted is that which is configured in the proxy. We will change our tree store proxy as follows:

proxy: {
  type: 'ajax',
  url: 'company/treenode.json'
}

Note that the URL of the proxy has been changed to treenode. This mapping, when implemented in CompanyHandler, will load one level at a time. The first request submitted by the proxy to load the top level of the tree will have the following format:

company/treenode.json?node=root

This will return the root node's list of companies:

{
    success: true,
    "children...