Extjs treepicker error when reading from a json format

Question

I'm still new in Extjs. I have a TreeStore which reads a JSON string as an input and I can represent it in a tree panel. But when I try to use the treestore in a tree picker there is get this error:

Is there anything missing here?

// try to find a record in the store that matches the value
        record = value ? me.store.getNodeById(value) : me.store.getRootNode();

Here is the JSON format:

{
  success: true,
  "children": [
    {
      "id": "G_1",
      "text": "group1",
      "leaf": false
    }, 
    {
      "id": "G_2",
      "text": "group2",
      "leaf": false
     }
  ]
}

And here is my TreeStore:

Ext.define('App.store.GroupTree', {
    extend: 'Ext.data.TreeStore',
    model: 'App.model.GroupTree',
    requires: 'App.model.GroupTree',
    proxy: {
        type: 'ajax',
        url: 'property/tree.json',
        reader: {  
            type: 'json',
            root:'children'
        }
    },
});

My treepicker item:

items: [
  {  
    xtype: 'treepicker',
    name: 'propertyCmb',
    fieldLabel: 'Property',
    labelWidth: 60,
    displayField: 'text',
    store: 'GroupTree',
    valueField: 'id',
    queryMode: 'local',
  }
]

Here is the treestore model code

Ext.define('App.model.GroupTree', {
    extend: 'Ext.data.Model',
    fields: [
        {name: 'id', type: 'string', useNull: true},
        {name: 'text', type: 'string'},
        {name: 'leaf', type: 'boolean'},
        {name: 'expanded', type: 'boolean'}
    ]
});

Answer 1

The error occurse, because the store is not auto created when assigned to your treepicker like store: 'GroupTree'. You have to create an instance of it first and that instance you need to assign to the treepicker. See the documentation http://docs.sencha.com/extjs/5.0.1/#!/api/Ext.ux.TreePicker-cfg-store .

The following should work

var groupStore = Ext.create('App.store.GroupTree');
groupStore.load();

var picker = Ext.create('Ext.ux.TreePicker',{
  name: 'propertyCmb',
  store: groupStore,
  fieldLabel: 'Property',
  labelWidth: 60,
  displayField: 'text',
  valueField: 'id',
  queryMode: 'local',
  renderTo: Ext.getBody()
});

A working fiddle can be found at https://fiddle.sencha.com/#fiddle/dip .