Setting Complex Attributes

Session and request attributes are string-to-string maps of attributes and values. In many cases, you can use the string map to transfer attribute values between your client application and a bot. In some cases, however, you might need to transfer binary data or a complex structure that can't be easily converted to a string map. For example, the following JSON object represents an array of the three most populous cities in the United States:

{
   "cities": [
      {
         "city": {
            "name": "New York",
            "state": "New York",
            "pop": "8537673"
         }
      },
      {
         "city": {
            "name": "Los Angeles",
            "state": "California",
            "pop": "3976322"
         }
      },
      {
         "city": {
            "name": "Chicago",
            "state": "Illinois",
            "pop": "2704958"
         }
      }
   ]
}

This array of data doesn't translate well to a string-to-string map. In such a case, you can transform an object to a simple string so that you can send it to your bot with the PostContent and PostText operations.

For example, if you are using JavaScript, you can use the JSON.stringify operation to convert an object to JSON, and the JSON.parse operation to convert JSON text to a JavaScript object:

// To convert an object to a string.
var jsonString = JSON.stringify(object, null, 2);
// To convert a string to an object.
var obj = JSON.parse(JSON string);

To send session attributes with the PostContent operation, you must base64 encode the attributes before you add them to the request header, as shown in the following JavaScript code:

var encodedAttributes = new Buffer(attributeString).toString("base64");

You can send binary data to the PostContent and PostText operations by first converting the data to a base64-encoded string, and then sending the string as the value in the session attributes:

"sessionAttributes" : {
   "binaryData": "base64 encoded data"
}