Once you create a form, you can render it with Actions using the api.prompt.render() method: 
// Example using the post-login trigger

exports.onExecutePostLogin = async (event, api) => {
  api.prompt.render(':form_id');
}

exports.onContinuePostLogin = async (event, api) => {
  // Add your logic after completing the form
}
Replace form_id with the ID of the Form. You can locate the ID in the URL of the Form, for example:  ap_pUMG... or select it from the Form editor Render tab. In the Actions Code editor, you can define the business logic to decide when and how to render the Form. 
exports.onExecutePostLogin = async (event, api) => {

  // Only render the form if user is missing company_name metadata
  if (!event.user.user_metadata.company_name) {
    api.prompt.render(':form_id');
  }
}

exports.onContinuePostLogin = async (event, api) => {
  // Add your logic after completing the form
}
To learn more these objects, review:
  • Event Object: Learn about the Event objects and properties.
  • API object: Learn about the API objects and methods.

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Populate values for existing fields and hidden fields (client-side)

You can populate values for existing fields and hidden fields using the fields property as a second argument in your render method. In the example below, the value Jane populates first_name field. 
exports.onExecutePostLogin = async (event, api) => {
  api.prompt.render(':form_id', {
    fields: {
      first_name: 'Jane',
    }
  });
}

exports.onContinuePostLogin = async (event, api) => {
  // Add your logic after completing the form
}
Do not populate sensitive information, populated values are exposed to the browser (client-side).
Make sure that the field ID referenced in the second argument is available client-side in your nodes and components; otherwise, the value will not populate.

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Inject custom data with shared variables (server-side)

You can inject server-side variables using the vars property as a second argument in your render method. This can be used to inject sensitive information without exposing it to the client-side. In the example below, the value 123456789 populates the variable external_user_id. 
exports.onExecutePostLogin = async (event, api) => {
  api.prompt.render(':form_id', {
    vars: {
      external_user_id: '123456789',
    }
  });
}

exports.onContinuePostLogin = async (event, api) => {
  // Add your logic after completing the form
}
Shared variables {{vars.*}} do not have data type restrictions.Shared variables {{vars.*}} are always automatically masked.Unlike when populating {{fields.*}} variables, the {{vars.*}} property does not need to exist in your form before injecting values.You can use the {{vars.*}} property to reference shared variables in your Forms and its linked Flows. To learn more, read Variables.

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Fields and shared variables data in Actions

Fields and shared variables data collected, in your forms, is automatically available with the event.prompt in the resume function of the current action:
  • The id property, with the prompt ID you’re rendering.
  • The fields object, which contains all your fields and hidden fields data.
  • The vars object, which contains all your shared variables data.
In the example below, the api.user.setUserMetadata populates the user_metadata company_name attribute with the event.prompt.fields.company_name property that was collected from your form. 
exports.onExecutePostLogin = async (event, api) => {
  api.prompt.render(':form_id');
}

exports.onContinuePostLogin = async (event, api) => {
  api.user.setUserMetadata('company_name', event.prompt.fields.company_name);
}

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Restrictions and limitations

  • You cannot redirect a user and render a form in the same Action. If you need to use both, consider using different Actions.
  • You can only render one form per Action. If you need to render more than one form, you need to render the forms in different Actions.
  • The same form can not be rendered more than once across the same trigger. For example, if you have a post-login trigger with two Actions, you can not render the same form in both Actions, you need to create different Forms for each Action.
  • The fields property size limit is 24 KB.
  • The api.prompt.render() method is available in the following triggers: