using-external-data-in-route-conditions.md

Using external data in route conditions

Sometimes you might want to grab some data from an external source as part of a user journey, and then use that data to determine how the user’s journey should proceed.

• When the user submits the form, pageA calls external Service X to grab the data item is_customer
• If is_customer === true then move the user to pageB, otherwise move the user to pageC

The recommended way to achieve this is to use a postvalidate hook (read more on hooks).

For example, in your pages file:

{
  waypoint: 'pageA',
  view: 'pages/pageA.njk',
  fields: aFields(),
  hooks: [{
    hook: 'postvalidate',
    middleware: async (req, res, next) => {
      const errors = req.casa.journeyContext.getValidationErrorsForPage(req.casa.waypoint);

      if (errors.length === 0)
        const response = await fetch('http://service-x/is-customer');

        // ...the rest of your middleware

        const json = await response.json();

        req.casa.journeyContext.data['pageA'].is_customer = json.is_customer;
      }

      next();
    }
  }]
}

Then in your plan file:

plan.setRoute("pageA", "pageB", (r, c) => c.data["pageA"].is_customer === true);
plan.setRoute(
  "pageA",
  "pageC",
  (r, c) => c.data["pageA"].is_customer === false,
);