IBM Watson. How to pass context from node to node?

Question

I"m trying to string together multiple IBM Watson requests:

Request #1: Play music.

Watson responds with the following:

{
"intents": [
    {
        "intent": "turn_on",
        "confidence": 0.9498470783233643
    }
],
"entities": [
    {
        "entity": "appliance",
        "location": [
            5,
            10
        ],
        "value": "radio",
        "confidence": 1
    }
],
"input": {
    "text": "play music"
},
"output": {
    "text": [
        "What kind of music would you like to hear?"
    ],
    "nodes_visited": [
        "node_1_1510258504338",
        "node_2_1510258615227"
    ],
    "log_messages": []
},
"context": {
    "conversation_id": "79e93cac-12bb-40fa-ab69-88f56d0845e4",
    "system": {
        "dialog_stack": [
            {
                "dialog_node": "node_2_1510258615227"
            }
        ],
        "dialog_turn_counter": 1,
        "dialog_request_counter": 1,
        "_node_output_map": {
            "node_2_1510258615227": [
                0
            ]
        }
    }
 }
}

Request #2: The patron would type rock.

My problem is that I'm getting an error message that states the following

No dialog node matched for the input at a root level. (and there is 1 more warning in the log)", "log_messages": [

I'm pretty sure I have to pass a context into the 2nd request but I'm not sure what I need to include. Right now I'm only passing in the conversation_id. is there something specific from the above response that I need to pass in? For example, I'm passing this:

{
"input": {
  "text": "rock"
},
"context": {
  "conversation_id": "79e93cac-12bb-40fa-ab69-88f56d0845e4"
 }
}

Answer 1

Your node that actions the type of music people select, is it a child of your 'turn_on' node [node_2_1510258615227]?
If so, as Simon demonstrates above, you need to also pass back as part of the API call the complete context packet. This informs Watson Conversation where in the dialog flow you were last. As the conversation system is state free, i.e. It does not store any state information about individual conversations, it will not by default know where it is within a conversation. This is why you then need to return the context element of the previous response, to allow watson to know where you were in the conversation flow.
Your error above states that Watson looked down the list of dialog nodes you have defined at your root level, and could not find a matching condition. Due to the fact your matching condition was within a child node.