# Add validation to a smart field edition

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## Add validation to a smart field edition

**Context**: I want to make sure that my users can only enter a value satisfying a certain set of conditions when editing a smart field.

Here I'm working on a collection `customers` and the smart field `'must-be-kuku'` should only accept the value `kuku`.

{% embed url="<https://www.loom.com/share/22641b6c62d9469ea244e12b4557f02e>" %}

`forest/customers.js`

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

// This file allows you to add to your Forest UI:
// - Smart actions: <https://docs.forestadmin.com/documentation/reference-guide/actions/create-and-manage-smart-actions>
// - Smart fields: <https://docs.forestadmin.com/documentation/reference-guide/fields/create-and-manage-smart-fields>
// - Smart relationships: <https://docs.forestadmin.com/documentation/reference-guide/relationships/create-a-smart-relationship>
// - Smart segments: <https://docs.forestadmin.com/documentation/reference-guide/segments/smart-segments>
collection('customers', {
  actions: [],
  fields: [
    {
      field: 'must-be-kuku',
      type: 'String',
      get(customer) {
        return 'kuku';
      },
      set(customer, value) {},
    },
  ],
  segments: [],
});
```

At the route level I need to check the user input from the edit form in the UI and check the value that has been entered into the field `'must-be-kuku'`.

`routes/customers.js`

```javascript
const express = require('express');
const { PermissionMiddlewareCreator } = require('forest-express-sequelize');
const { customers } = require('../models');

const router = express.Router();
const permissionMiddlewareCreator = new PermissionMiddlewareCreator(
  'customers'
);

// Update a Customer
router.put(
  '/customers/:recordId',
  permissionMiddlewareCreator.update(),
  (request, response, next) => {
    if (request.body.data.attributes['must-be-kuku'] !== 'kuku') {
      return response.status(403).send('should have been kuku!');
    }
    next();
  }
);

module.exports = router;
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.forestadmin.com/documentation/reference-guide/smart-fields/smart-field-examples/add-validation-to-a-smart-field-edition.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.