Kana home pagelight logo
Javascript
Block Feature Access (Backend)

Sometimes your users may not be allowed to access a particular feature because they aren’t subscribed to a plan with that feature, or they have no further allowance of that feature remaining. You’re going to want to identify if they are allowed to use a feature in order to grant or block access.

You should implement this each time you create a feature within Kana to ensure your user’s don’t accidentally use the feature in question when they shouldn’t.

​
Prerequisites

You will need to ensure you have details on both:

  • The user who has used the feature

  • The feature which the user has used

If neither the user nor feature exist yet in Kana, then you should create these first:

Create Users

Create Features

Once these are created, you will need to ensure you know the id of both.

Both theid for a User and a Feature are defined by you upon creation in Kana.

You can find the identifiers for both in the Dashboard, or by using the features and users queries to pull all respective records and grab the id from the one you need.

​
Code Sample

​
Basic

Node.js
import { KanaAdmin } from "@usekana/admin-kana-js";

const client = new KanaAdmin({
  apiKey: API_KEY, // Replace with own Private API Key
});

const { data, error } = await client.features.canUse({
  userId: "124",
  featureId: "api-calls",
});
console.log(data);
console.log(error);

​
Example

Node.js
import { KanaAdmin } from '@usekana/admin-kana-js';
import { sendMessage } from '/modules/sendMessage.js'

const client = new KanaAdmin({
    apiKey: {API_KEY}
});

app.post('/message', function(req, res, next) {
  const userId = req.user.id; // Assumes passport is being used for auth
  const featureId = 'messages'

  const message = req.body.message // Assumes message is being sent as object in request body

  const checkAccessAndSendMessage = async () => {
    const { data, error } = await client.features.canUse({userId: userId, id: featureId});
    if (error) {
      return error;
    }
    if (data) {
      if (data.access == true) {
        const sentMessage = sendMessage(message);
        return sentMessage;
      } else {
        throw new Error("Kana: User cannot access feature");
      }
    }
  };

  checkAccessAndSendMessage().
    .then((result) => {
      console.log(result);
      res.status(200).send('Message was successfully sent');
    .catch((error) => {
      console.log(error);
      res.status(403).send(error.message);
  });
});

This should always take place before the feature is used. It should be the first thing you do to ensure you return as early as possible when they don’t have access, preventing any unnecessary continuation or accidental usage.

​
Next Steps

Congratulations 🎉 You’ve now successfully checked a users entitlement to a feature and blocked them from using the feature if they should have no access.

You should look to ensure this is setup for all your features and in all places where those features could be used by customers. For instance, if you had a messages feature, your users may be able to send messages via your UI and through an API call - both should block access when necessary.

You may want to also implement something similar on the frontend of your application to prevent feature access at source.

Block Feature Access (Frontend)

If you haven’t yet recorded usage of your features when access is granted, we strongly recommend this as a next step. It’s a key requirement in order for us to understand a user’s entitlement towards a feature.

Record Feature Usage