JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://cdn.sencha.io/ext-4.1.1-gpl/resources/css/ext-all.css">

JavaScript

Ext.define('a', {
    extend: 'Ext.data.Model',
    fields: ['id', 'name'],
    associations: [{
        type: 'hasOne',
        model: 'b'
    }]
});

Ext.define('b', {
    extend: 'Ext.data.Model',
    fields: [{
        name: 'id',
        type: 'int'
    },{
        name: 'ldap'
    }]
});

Ext.onReady(function () {
    var store = Ext.create('Ext.data.ArrayStore', {
        model: 'a',
        data: [{
            id: '1',
            name: 'user-1',
            b: {
                id: 2,
                ldap: 'ert'
            }
        }, {
            id: '2',
            name: 'user-2',
            b: {
                id: 1,
                ldap: 'dfg'
            }
        }, {
            id: '3',
            name: 'user-3',
            b: {
                id: 3,
                ldap: 'hjk'
            }
        }, {
            id: '4',
            name: 'user-4',
            b: {
                id: 1,
                ldap: 'yuio'
            }
        }, {
            id: '5',
            name: 'user-5',
            b: {
                id: 3,
                ldap: 'ljjolic'
            }
        }],
        proxy: {
            type: 'memory',
            reader: {
                type: 'json'
            }
        }
    });

	var d = Ext.create("a");
  console.log("ASD")
  d.set('name', 'fff');
  console.log("ASD1")
  d.getb().set('ldap', 'asd')
  console.log("ASD2")
  console.log(d.getb().get('ldap'));
  
    Ext.widget({
        xtype: 'grid',
        title: 'Records',
        width: 400,
        height: 180,
        store: store,
        renderTo: Ext.getBody(),
        columns: [{
            text: 'id',
            dataIndex: 'id'
        }, {
            text: 'name',
            dataIndex: 'name'
        }, {
            text: 'b_id',
            renderer: function (v, m, r) {
                return r.getb().get('id');
            }
        }, {
         		text:'b_ldap',
         		renderer: function(v, m, r){
           ...