Smart Segments

This is the official documentation of the @forestadmin/agent Node.js agent.

Smart Segments should be quick to migrate, as the syntax is very similar to the legacy agent.

You can find the full documentation of segment customization here.

Code cheatsheet

Legacy agent	New agent
where:	handler body
sequelize.where	condition tree

How to migrate

Structure

Because the new Forest Admin agent is designed to work with multiple databases, the return value of the filter function is not a Sequelize or Mongoose condition anymore.

Instead, you'll be building a condition tree that will be translated to the appropriate database syntax by the agent.

Performance

All queries cannot be expressed in the Forest Admin query interface, but many can.

You can have great performance improvements by using the Forest Admin query interface to build your conditions, instead of performing the query yourself, and then building a naive condition tree, which filters by primary key like in the example we're providing.

Example

In this example, we migrate a segment that returns the 5 bestsellers of a product collection.

Before

collection('products', {
  segments: [
    {
      name: 'Bestsellers',
      where: async product => {
        const query = `
        SELECT products.id, COUNT(orders.*)
        FROM products
        JOIN orders ON orders.product_id = products.id
        GROUP BY products.id
        ORDER BY count DESC
        LIMIT 5;
      `;

        const products = await models.connections.default.query(query, {
          type: QueryTypes.SELECT,
        });

        return { id: { [Op.in]: products.map(product => product.id) } };
      },
    },
  ],
});

After

agent.customizeCollection('products', products => {
  products.addSegment('Bestsellers', async () => {
    const query = `
      SELECT products.id, COUNT(orders.*)
      FROM products
      JOIN orders ON orders.product_id = products.id
      GROUP BY products.id
      ORDER BY count DESC
      LIMIT 5;
    `;

    const products = await models.connections.default.query(query, {
      type: QueryTypes.SELECT,
    });

    return { field: 'id', operator: 'In', value: products.map(p => p.id) };
  });
});