book.js

	Ext.define('Book', {
	    extend: 'Ext.data.Model',
	    fields: [
			{name: 'id',  type: 'int'},
			{name: 'title',  type: 'string'},
			{name: 'thumb_image_path',  type: 'string'},
			{name: 'user_id',  type: 'int'}
		],
		proxy: { url: "/books", type: 'rest', format: "json" }
	});

booksformpanel.js

Ext.define("BooksFormPanel", {
    extend: "Ext.form.Panel",
    alias: "widget.booksformpanel",
    salvar: function(){
        var json = this.getForm().getValues();
        this.update_attributes( json );
        if( this.callback ) this.callback.call( this.parentScope || this )
    },
    update_attributes: function(json) {
        var model = this.getForm().getRecord();
        for(var field in json) {
            model.set(field, json[field] );
        }
        model.save();
    },
    initComponent: function() {
        this.items = [
            { xtype: "textfield", fieldLabel: "Title", name: "title" },
            { xtype: "hidden", name: "id" },
        ];
        this.buttons = [{text: "Salvar", handler: this.salvar, scope: this}]
        this.callParent(arguments);
        this.getForm().loadRecord(this.model);
    }
})

booksgrid.js

Ext.define("BooksGrid", {
    extend: "Ext.grid.Panel",
    alias: "widget.booksgrid",
    abrirTela: function(record) {
        
Ext.create('Ext.window.Window', {
    title: "Editar livro", modal:true,
    width: 400,
    items: [{xtype: "booksformpanel", model: record}]
}).show();


    },
    initComponent: function() {
        this.columns = [{
          header: "Title", dataIndex: "title"
        }];
        this.store = {model: "Book"};

        this.listeners = {
            itemdblclick: {
                scope: this,
                fn: function(g, record){ this.abrirTela(record) }
            }
        };
        this.callParent(arguments);
        this.store.load();
    }
})

Ext.create('Ext.window.Window', {
    title: "Lista de livros",
    width: 400,
    items: [{xtype: "booksgrid"}]
}).show();