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Reuse variables across topics

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Variables store your customers' responses to questions from your agent. For example, you can save a customer's name in a variable called UserName. The agent can then address the customer by name as the conversation continues.

By default, a variable's value can only be used in the topic where the variable is created. However, it's possible to reuse the same value across topics. For example, a Welcome topic asks for the customer's name and email address. In the Appointment Booking topic, you want the agent to remember what the customer entered and not ask again.

One way to reuse a variable is to pass the variable between topics. The other way is to make the variable global in scope, and that's what this article covers. Global variables are called that because they're available in all topics across the entire agent.

Global variables apply during a single user session. You specify which variables are global variables to distinguish them from topic-level variables.

Create a global variable

You create a global variable by changing the scope of a topic variable.

  1. Create a variable or use the Variables pane to open an existing variable.

  2. On the Variable properties panel, select Global (any topic can access).

    The variable name is given the prefix Global. to differentiate it from topic-level variables. For example, the variable UserName is displayed as Global.UserName.

  3. Save the topic.

    The name of a global variable must be unique across all topics.

Use global variables

When you're composing a message in a Message node or a Question node, select the {x} icon to view the variables that are available to the topic. Global variables appear in the Custom tab along with any topic variables. Variables are listed in alphabetical order.

Find all topics using a global variable

You can find where a global variable is defined and what other topics are using it. This feature can be useful if you're working on a new agent, or if you have multiple variables and complex topic branching.

  1. Select the desired global variable on the authoring canvas, or in the Variables panel.

  2. On the Variable properties panel, in the Reference section, select View all references.

  3. Switch to the Other tab, and select any topic where the variable is used to go directly to that topic and node.

Lifecycle of global variables

By default, the value of a global variable persists until the session ends. The Clear Variable Values node resets the values of global variables and is used in the Reset Conversation system topic. That topic can be triggered either by redirection or when the user enters a trigger phrase such as "Start over." In that case, all global variables are reset.

Set a global variable's value from external sources

If you want to make sure the agent starts a conversation with some context, you can initialize a global variable with an external source. Let's say that your site requires users to sign in. Since your agent already knows a user's name, it can greet customers by name before they start typing their first question.

  1. Select a global variable.

  2. On the Variable properties pane, select External sources can set values.

Set global variables in an embedded agent

If you're embedding your agent in a simple web page, you can append variables and their definitions to the agent's URL. Or, if you'd like a little more control, you can use a <script> code block to call and use variables programmatically.

The variable name in the query string of the URL must match the name of the global variable without the Global. prefix. For example, a global variable Global.UserName would be referred to as UserName in the query.

The examples that follow uses a basic declaration for the variables. In a production scenario, you might pass in as the query parameter or variable definition another variable that already stores the user's name (for example, if you have the user name from a sign-in script).

Append the variables and their definitions to the agent's URL as query string parameters in the format botURL?variableName1=variableDefinition1&variableName2=variableDefinition2.

For example:

The parameter name is case-insensitive. username=Ana would also work in this example.

Add global variables to a custom canvas

You can also add the variable to a custom canvas.

  1. In the <script> section on the page where you have your agent, define the variables as follows, substituting variableName1 for the variable name without the Global. prefix and variableDefinition1 for the definition. Separate multiple variables with commas (,).

       const store = WebChat.createStore({}, ({ dispatch }) => next => action => {
     if (action.type === 'DIRECT_LINE/CONNECT_FULFILLED') {
       dispatch({
          type: "WEB_CHAT/SEND_EVENT",
          payload: {
            name: "pvaSetContext",
            value: {
               "variableName1": "variableDefinition1",
               "variableName2": "variableDefinition2"
            }
          },
        });
      }
        return next(action);
    });

  2. In your <script> section, call the store when you embed your agent, as in the following example where store is called just before where styleOptions is called (you must replace the BOT_ID with your agent's ID):

    const BOT_ID = "12345-5678";
const theURL = "https://powerva.microsoft.com/api/botmanagement/v1/directline/directlinetoken?botId=" + BOT_ID;

fetch(theURL)
    .then(response => response.json())
    .then(conversationInfo => {
        window.WebChat.renderWebChat(
            {
                directLine: window.WebChat.createDirectLine({
                    token: conversationInfo.token,
                }),
                store,
                styleOptions
            },
            document.getElementById('webchat')
        );
    })
    .catch(err => console.error("An error occurred: " + err));

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