Finding ExtJS component for Selenium WebDriver

ExtComponentQuery.java

//find the fully qualified component query of ExtJS component cmp
String query = cmp.componentQuery;
Component parent = cmp.parent;

while (parent != null) {
  query = parent.componentQuery + " " + query;
	parent = parent.parent;
}
//use component query to find id
String js = "return Ext.ComponentQuery.query(\"" + query + "\")[0].id;";
String id = (String) ((JavascriptExecutor) _driver).executeScript(js);

WebElement element = driver.findElement(By.id(id));