> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/upstash/redis-js/llms.txt
> Use this file to discover all available pages before exploring further.

# HSET

> Set hash field values

## Usage

Sets the specified fields to their respective values in the hash stored at `key`. This command overwrites any specified fields already existing in the hash.

```typescript theme={null}
await redis.hset(key, fieldValueObject);
```

## Parameters

<ParamField path="key" type="string" required>
  The key of the hash
</ParamField>

<ParamField path="fieldValueObject" type="Record<string, TData>" required>
  An object containing field-value pairs to set in the hash. Each key in the object represents a field name, and its value is the value to set.
</ParamField>

## Response

<ResponseField name="count" type="number">
  The number of fields that were added or updated in the hash.
</ResponseField>

## Examples

### Set multiple hash fields

```typescript theme={null}
import { Redis } from '@upstash/redis';

const redis = new Redis({
  url: process.env.UPSTASH_REDIS_REST_URL!,
  token: process.env.UPSTASH_REDIS_REST_TOKEN!,
});

// Set multiple fields at once
const count = await redis.hset('user:1000', {
  name: 'Alice',
  email: 'alice@example.com',
  age: 30
});
console.log(count); // 3

// Update existing fields
const updated = await redis.hset('user:1000', {
  age: 31,
  city: 'New York'
});
console.log(updated); // 2 (age updated, city added)
```

### Set a single field

```typescript theme={null}
// Set one field
await redis.hset('user:1000', { status: 'active' });
```

### Store complex objects

```typescript theme={null}
interface Profile {
  bio: string;
  website: string;
}

const profile: Profile = {
  bio: 'Software engineer',
  website: 'https://example.com'
};

await redis.hset('user:1000:profile', profile);
```

### Store JSON data

```typescript theme={null}
// Complex data is automatically serialized
await redis.hset('user:1000', {
  preferences: JSON.stringify({ theme: 'dark', notifications: true }),
  metadata: JSON.stringify({ lastLogin: Date.now() })
});
```

## See Also

* [HGET](/api/commands/hget) - Get a hash field value
* [HMSET](/api/commands/hmset) - Set multiple hash fields (legacy)
* [HGETALL](/api/commands/hgetall) - Get all fields and values in a hash