> ## 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.

# HMSET

> Set multiple hash fields (legacy)

## 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.hmset(key, fieldValueObject);
```

<Note>
  As of Redis 4.0.0, `HMSET` is considered deprecated. Use `HSET` with multiple field-value pairs instead, which has the same behavior.
</Note>

## 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="status" type="'OK'">
  Always returns `'OK'` when successful.
</ResponseField>

## Examples

### Set multiple 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 result = await redis.hmset('user:1000', {
  name: 'Alice',
  email: 'alice@example.com',
  age: 30,
  city: 'New York'
});
console.log(result); // 'OK'
```

### Update existing fields

```typescript theme={null}
// Set initial data
await redis.hmset('user:1000', {
  name: 'Alice',
  email: 'alice@example.com'
});

// Update fields (overwrites existing)
await redis.hmset('user:1000', {
  email: 'alice.new@example.com',
  city: 'Boston'
});

const user = await redis.hgetall('user:1000');
console.log(user);
// { name: 'Alice', email: 'alice.new@example.com', city: 'Boston' }
```

### Initialize configuration

```typescript theme={null}
// Set application configuration
await redis.hmset('config:app', {
  maxConnections: 100,
  timeout: 5000,
  retryAttempts: 3,
  enableCache: true
});
```

### Store session data

```typescript theme={null}
interface SessionData {
  userId: string;
  createdAt: string;
  expiresAt: string;
  ipAddress: string;
}

const sessionData: SessionData = {
  userId: '1000',
  createdAt: new Date().toISOString(),
  expiresAt: new Date(Date.now() + 3600000).toISOString(),
  ipAddress: '192.168.1.1'
};

await redis.hmset('session:abc123', sessionData);
```

### Migrate from HMSET to HSET

```typescript theme={null}
// Old way (HMSET - deprecated)
await redis.hmset('user:1000', {
  name: 'Alice',
  email: 'alice@example.com'
});

// New way (HSET - recommended)
await redis.hset('user:1000', {
  name: 'Alice',
  email: 'alice@example.com'
});

// Both produce the same result
```

### Bulk insert user data

```typescript theme={null}
const users = [
  { id: '1000', name: 'Alice', email: 'alice@example.com' },
  { id: '2000', name: 'Bob', email: 'bob@example.com' },
  { id: '3000', name: 'Charlie', email: 'charlie@example.com' }
];

// Insert all users
await Promise.all(
  users.map(user => 
    redis.hmset(`user:${user.id}`, {
      name: user.name,
      email: user.email
    })
  )
);
```

### Set default values

```typescript theme={null}
// Set default user preferences
await redis.hmset('user:1000:preferences', {
  theme: 'light',
  language: 'en',
  notifications: true,
  emailDigest: 'daily'
});
```

## Notes

* Always returns `'OK'` on success (unlike `HSET` which returns the count)
* As of Redis 4.0.0, this command is deprecated in favor of `HSET`
* `HSET` can accept multiple field-value pairs and has the same behavior as `HMSET`
* The command overwrites existing fields
* If the key does not exist, a new hash is created
* Consider using `HSET` for new implementations

## Migration Guide

Replace `HMSET` with `HSET` in your code:

```typescript theme={null}
// Before
await redis.hmset('key', { field1: 'value1', field2: 'value2' });

// After
await redis.hset('key', { field1: 'value1', field2: 'value2' });
```

The main difference is the return value:

* `HMSET` returns `'OK'`
* `HSET` returns the number of fields added/updated

## See Also

* [HSET](/api/commands/hset) - Set hash field values (recommended)
* [HGET](/api/commands/hget) - Get a hash field value
* [HMGET](/api/commands/hmget) - Get multiple hash field values
* [HGETALL](/api/commands/hgetall) - Get all fields and values in a hash