# Sort by smart field that includes value from a belongsTo relationship

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## Sort by smart field that includes value from a belongsTo relationship

**Context**: As a user I want to be able to sort records based on a smart field where the smart field includes data from the current record's parent.

**Example**: Here I have a model `orders` that has a belongsTo relationship with the `customers` model.

I have a smart field in the `orders` model called `customer email` that returns the value of the parent customer's email field. I want to sort the orders by the `customer email` smart field.

#### Implementation

`forest/orders.js`

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

collection('orders', {
  actions: [],
  fields: [
    {
      field: 'customer email',
      get: (order) =>
        models.customers
          .findByPk(order.customer.dataValues.id)
          .then((customer) => customer.email),
      isSortable: true,
    },
  ],
  segments: [],
});
```

`routes/orders.js`

```javascript
router.get(
  '/orders',
  permissionMiddlewareCreator.list(),
  (request, response, next) => {
    if (request.query.sort.includes('customer email')) {
      request.query.sort = request.query.sort.includes('-')
        ? '-customer.email'
        : 'customer.email';
    }
    next();
  }
);
```