title: how to get generic template data in button data response in chatbot messenger using nodejs?
body: <p>I'm developing a messenger chatbot to sell clothes using node and a little of diagflow, but I'm stuck in the productcart, this is the problem:
  I'm using a generic template with a postback button "add item"  and payload "additem_database", to add an item to my database, but I'm having difficulty finding a way to identify the item that I'm adding, when I click, the response is something like that :</p>
  
  <pre><code>    {"object":"page","entry":[{"id":"596254160722097","time":1523729982009,
  "messaging":[{"recipient":{"id":"596257560734097"},
  "timestamp":1523729982009,
  "sender":{"id":"16304620870031321"},
  "postback":{"payload":"additem_database",
  "title":"add item"}}]}]}
      Received postback for user 1630462087003321 and
   page 596257160724245 with payload 'additem_database' at 1523729982784
  </code></pre>
  
  <p>this only gives me the title of the button and the payload, the only solution that I thought was to name the button title with the same name of the product like this "add t-shirt", and then use the button title to find in my database and add to my cart, but this is not the best solution, so, my question is:</p>
  
  <p>there is a way to get all the generic template data as a response when I click on the button, instead of only get the button data? or there is another type of data that I can use in the button response to use as an identifier?</p>
  
  <p>Thank you if you had the time to read all.</p>