Reuse variables across topics


There is additional information available for people using Power Virtual Agents (preview).

Select the version of Power Virtual Agents you're using here:

Variables let you save responses from your customers. For example, you can save a customer's name in a variable called UserName. The bot 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 this variable gets created. However, you might want the bot to use the same value across topics. This means the bot can remember the necessary context when a conversation spans multiple topics.

For example, in a "Welcome" topic, the bot asks for the customer's name and email. Then when the conversation goes to another topic, such as an "Appointment booking" topic, you want the bot to remember this customer's name and email address.

In some systems, these types of variables are known as global variables. In Power Virtual Agents, these variables are called bot variables, because they apply across the entire bot.

Bot variables apply during a single user session. You specify which variables should be treated as bot variables to distinguish them from topic-level variables.


Set bot variables

After you set a bot variable, it will be available to all topics.

When you select the {x} button in a message node or question node when you're composing a bot message, you'll see that the bot variable is available. Variables are sorted in alphabetical order, so you'll find that all bot variables are grouped together in the variable menu because they all begin with bot..

Screenshot showing selection of the x variable icon to display a list of variables.

When you use a condition node, a flow action node, or a skill node, you'll also see bot variables available there.

Reuse a variable across topics by setting it as a bot variable

  1. Select any variable in the authoring canvas.

  2. On the Variable properties pane, under Usage, select Bot (any topic can access).

  3. The variable name will be given a prefix string bot., to differentiate it from the topic-level variables. For example, the variable UserName is now shown as bot.UserName.

Screenshot showing the Variable Properties pane, with the Usage section highlighted


A bot variable's name must be unique across all topics. In the case of a conflict, you'll need to rename the variable before saving your change.

Manage bot variables

After you've created a bot variable, you can see where it's first defined and what other topics are using it. This can be useful if you're working on a new bot, or if you have multiple variables and complex topic branching.

Go to the source of a bot variable's definition

  1. Select any variable in the authoring canvas.

  2. On the Variable properties pane, select Go to source.

Screenshot showing the Variable Properties pane, with the Go to Source button highlighted

This will take you to the node in the topic where the bot variable was created.

Find all topics using a bot variable

  1. Select any bot variable in the authoring canvas.

  2. On the Variable properties pane, in the Used by section, select any of the topics where the variable is used to go straight to that topic and node.

Screenshot showing the list of topics used by a variable in the Variable Properties pane.

Bot variable initialization

If a bot variable is triggered before it has been initialized (or "filled in"), the bot will automatically trigger the part of the topic where the bot variable is first defined—even when it's in a different topic—before returning to the original topic. This allows the bot to have all the variables filled in without interrupting the conversation.

For example, the customer starts the conversation on the "Appointment booking" topic, in which a bot variable bot.UserName is used. However, the bot.UserName variable is first defined in the "Welcome" topic.

When the conversation comes to the point in the "Appointment booking" topic where bot.UserName is referenced, the bot will seamlessly pivot to the question node where bot.UserName is first defined.

After the customer answers the question, the bot will resume the "Appointment booking" topic.

Bot variable behavior when implementing Actions via Power Automate flows or skills

Sometimes, you might use a flow or skill to initialize or fill in a variable in a chatbot.

When a user interacts with the chatbot, however, the variable might be filled in at an earlier point in the conversation, or you may have already set the variables externally.

In this situation, the flow or skill will still run and fill in the variable, overwriting whatever was previously stored in the variable.

Bot variables lifecycle and resetting its value

Bot variables are accessible from any topic, and the bot variable's assigned value persists throughout the session.

The value is only cleared when the bot user is redirected to the Start over system topic, or when the user triggers this topic directly (for example, by typing Start over). In this case, all bot variables will be reset and won't have any values.

Set a bot variable's value from external sources

You can set a bot variable to be initialized with an external source. This lets the bot start the conversation with some context.

For example, a customer brings up a bot chat from your web site, and the site already knows the customer's name. You let the bot know the user's name before starting the conversation, and the bot can have a more intelligent conversation with the customer without having to ask for their name again.

Set bot variable from external source

  1. Select any variable in the authoring canvas.

  2. On the Variable properties pane, in the Usage section, select the checkbox External sources can set values.

Screenshot of the Usage section on the Variable Properties pane, with the Bot option and External sources can set values checkbox both selected

  1. You can append the variables and their definitions if you're simply embedding your bot in a simple webpage, or you can use a <script> code block to call and use variables programatically.


    The variable name in the query string must match that of the bot variable, without the bot. prefix. For example, a bot variable bot.UserName must be rendered as UserName=.

In the examples described here, a simple declaration is made for the variables. In a production scenario, you might pass in as the query parameter or variable definition another variable that has already stored the user's name (for example, if you have the user name from a sign-in script).

To add the variable to an embedded bot

  1. Append the variables and their definitions to the bot's URL as query string parameters (in the format of botURL?variableName1=variableDefinition1&variableName2=variableDefinition2), for example:

  2. The parameter name is case-insensitive. This means username=Renata will also work in this example.

To add the variable to a custom canvas

  1. In the <script> section on the page where you have your bot, define the variables as follows, substituting variableName1 for the variable name without the bot. 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') {
              type: "WEB_CHAT/SEND_EVENT",
              payload: {
                name: "pvaSetContext",
                value: {
                   "variableName1": "variableDefinition1",
                   "variableName2": "variableDefinition2"
            return next(action);
  2. Within your <script> section, call the store when you embed your bot, as in the following example where store is called just above where styleOptions is called (you'll need to replace the BOT_ID with your ID):

    const BOT_ID = "12345-5678";
    const theURL = "" + BOT_ID;
        .then(response => response.json())
        .then(conversationInfo => {
                    directLine: window.WebChat.createDirectLine({
                        token: conversationInfo.token,
        .catch(err => console.error("An error occurred: " + err));

Delete bot variables

When removing a bot variable used in other topics, the references to that variable in the topics will be marked as Unknown.

You'll receive a warning about deleting the bot variable before you can confirm the operation.

The bot variable delete message indicates that references to that variable will be labeled as unknown.

Nodes that contain references to the deleted bot variable will tell you they contain an unknown variable.

Screenshot of a node with references to an unknown variable, which are marked as red within the message node's text, and indicated with a warning that says Bot message contains unknown variable

Topics with nodes that contain references to deleted bot variables might stop working. Ensure that you remove or correct all the topics that were using the deleted variable before publishing.

Depending on the bot's authentication setup, you will have a set of bot variables associated with the authentication provider available to you. For details about which set of variables are available and how to use them, see the Add end-user authentication to a Power Virtual Agents bot documentation topic.