> ## Documentation Index
> Fetch the complete documentation index at: https://forest-chore-open-api.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Link users and Dwolla customers

The implementation of this [smart relationship (belongsTo](/legacy/javascript-agents/reference-guide/models/relationships/create-a-smart-relationship/overview#creating-a-belongsto-smart-relationship)) relies on a Dwolla service that will retrieve the Dwolla customer based on the user's email. The Dwolla service is described in [another section](/legacy/javascript-agents/reference-guide/integrations/dwolla/dwolla-service).

```javascript theme={null}
// forest/users.js
const { collection } = require('forest-express-sequelize');

const DwollaService = require('../services/dwolla-service');
let dwollaService = new DwollaService(
  process.env.DWOLLA_APP_KEY,
  process.env.DWOLLA_APP_SECRET,
  process.env.DWOLLA_ENVIRONMENT
);

collection('users', {
  actions: [],
  fields: [
    {
      field: 'dwollaCustomer',
      type: 'String',
      reference: 'dwollaCustomers.id',
      get: function (user) {
        return dwollaService.getCustomerSmartRelationship(user);
      },
    },
  ],
  segments: [],
});
```