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Smart Collections

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This is the documentation of the forest-express-sequelize and forest-express-mongoose Node.js agents that will soon reach end-of-support.

forest-express-sequelize v9 and forest-express-mongoose v9 are replaced by @forestadmin/agent v1.

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Smart Collections

What is a Smart Collection?

A Smart Collection is a Forest Collection based on your API implementation. It allows you to reconcile fields of data coming from different or external sources in a single tabular view (by default), without having to physically store them into your database.

Fields of data could be coming from many other sources such as other B2B SaaS (e.g. Zendesk, Salesforce, Stripe), in-memory database, message broker, etc.

This is an advanced notion. If you're just starting with Forest Admin, you should skip this for now.

In the following example, we have created a Smart Collection called customer_statsallowing us to see all customers who have placed orders, the number of order placed and the total amount of those orders.

For an example of advanced customization and featuring an Amazon S3 integration, you can see here how we've stored in our live demo the companies' legal documents on Amazon S3 and how we've implemented a Smart Collection to access and manipulate them.

Creating a Smart Collection

First, we declare the customer_stats collection in the forest/ directory.

In this Smart Collection, we want to display for each customer its email address, the number of orders made (in a field orders_count) and the sum of the price of all those orders (in a field total_amount).

You can check out the list of available field options if you need it.

You MUST declare an id field when creating a Smart Collection. The value of this field for each record MUST be unique.

As we are using the customer id in this example, we do not need to declare an id manually.

forest/customer_stats.js
const { collection } = require('forest-express-sequelize');
const models = require('../models');

collection('customer_stats', {
  isSearchable: true,
  fields: [
    {
      field: 'email',
      type: 'String',
    },
    {
      field: 'orders_count',
      type: 'Number',
    },
    {
      field: 'total_amount',
      type: 'Number',
    },
  ],
});

The optionisSearchable: true added to your collection allows to display the search bar. Note that you will have to implement the search yourself by including it into your own get logic.

Implementing the GET (all records)

At this time, there’s no Smart Collection Implementation because no route in your app handles the API call yet.

In the file routes/customer_stats.js, we’ve created a new route to implement the API behind the Smart Collection.

The logic here is to list all the customers that have made orders (with their email), to count the number of orders made and to sum up the price of all the orders.

The limit and offset variables are used to paginate your collection according to the number of records per page set in your UI.

We have implemented a search logic to catch if a search query (accessible through req.query.search) has been performed and to return all records for which the email field matches the search.

Finally, the last step is to serialize the response data in the expected format which is simply a standard JSON API document. A class called RecordSerializer is made available to help you serialize the records. You can read more about this class here.

/routes/customer_stats.js
const { RecordSerializer } = require('forest-express-sequelize');
const express = require('express');
const router = express.Router();
const { connections } = require('../models');

const sequelize = connections.default;

router.get('/customer_stats', (req, res, next) => {
  const limit = parseInt(req.query.page.size) || 20;
  const offset = (parseInt(req.query.page.number) - 1) * limit;
  const queryType = sequelize.QueryTypes.SELECT;
  let conditionSearch = '';

  if (req.query.search) {
    conditionSearch = `customers.email LIKE '%${req.query.search.replace(
      /\'/g,
      "''"
    )}%'`;
  }

  const queryData = `
    SELECT customers.id,
      customers.email,
      count(orders.*) AS orders_count,
      sum(products.price) AS total_amount,
      customers.created_at,
      customers.updated_at
    FROM customers
    JOIN orders ON customers.id = orders.customer_id
    JOIN products ON orders.product_id = products.id
    ${conditionSearch ? `WHERE ${conditionSearch}` : ''}
    GROUP BY customers.id
    ORDER BY customers.id
    LIMIT ${limit}
    OFFSET ${offset}
  `;

  const queryCount = `
    SELECT COUNT(*)
    FROM customers
    WHERE
      EXISTS (
        SELECT *
        FROM orders
        WHERE orders.customer_id = customers.id
      )
      ${conditionSearch ? `AND ${conditionSearch}` : ''}
  `;

  Promise.all([
    sequelize.query(queryData, { type: queryType }),
    sequelize.query(queryCount, { type: queryType }),
  ])
    .then(async ([customerStatsList, customerStatsCount]) => {
      const customerStatsSerializer = new RecordSerializer({
        name: 'customer_stats',
      });
      const customerStats = await customerStatsSerializer.serialize(
        customerStatsList
      );
      const count = customerStatsCount[0].count;
      res.send({ ...customerStats, meta: { count: count } });
    })
    .catch((err) => next(err));
});

module.exports = router;

Now we are all set, we can access the Smart Collection as any other collection.

In this example we have only implemented the GET all records action but you can also add the following actions: GET specific records, PUT, DELETE and POST. These are shown in the next page explaining how a Smart Collection can be used to access and manipulate data stored in Amazon S3.

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