---
title: "Client.hsetnx(key, field, value) | Grafana k6 documentation"
description: "Sets the value of field in the hash stored at `key` to `value` only if field does not exist in the hash."
---

# Client.hsetnx(key, field, value)

Sets the specified field in the hash stored at `key` to `value`, only if `field` does not yet exist. If `key` does not exist, a new key holding a hash is created. If `field` already exists, this operation has no effect.

### Parameters

Expand table

| Parameter | Type   | Description                               |
|-----------|--------|-------------------------------------------|
| `key`     | string | key holding the hash to set the field of. |
| `field`   | string | field to set in the hash.                 |
| `value`   | string | value to set the field to.                |

### Returns

Expand table

| Type               | Resolves with                                                                                                                                                                         | Rejected when |
|--------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|
| `Promise<boolean>` | On success, the promise resolves with `1` if `field` is a new field in the hash and value was set, and with `0` if `field` already exists in the hash and no operation was performed. |               |

### Example

JavaScript ![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```javascript
import redis from 'k6/x/redis';

// Instantiate a new redis client
const redisClient = new redis.Client('redis://localhost:6379');

export default async function () {
  await redisClient.hsetnx('myhash', 'myfield', 'myvalue');
  await redisClient.hsetnx('myhash', 'myotherfield', 'myothervalue');

  const set = await redisClient.hsetnx('myhash', 'myfield', 'mynewvalue');
  if (set === true) {
    throw new Error('hsetnx should have failed on existing field');
  }
}
```