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Add Production usage docs for Node-Redis (#2696)
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* Add Production usage docs for Node-Redis

* Update docs/connect/clients/nodejs.md

Co-authored-by: David Dougherty <[email protected]>

* Update docs/connect/clients/nodejs.md

Co-authored-by: David Dougherty <[email protected]>

* Update docs/connect/clients/nodejs.md

Co-authored-by: David Dougherty <[email protected]>

* Update docs/connect/clients/nodejs.md

Co-authored-by: David Dougherty <[email protected]>

* Update docs/connect/clients/nodejs.md

Co-authored-by: David Dougherty <[email protected]>

* Update docs/connect/clients/nodejs.md

Co-authored-by: David Dougherty <[email protected]>

* Address review suggestions

---------

Co-authored-by: David Dougherty <[email protected]>
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uglide and dwdougherty authored Mar 26, 2024
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Expand Up @@ -136,166 +136,77 @@ await client.disconnect();

You can also use discrete parameters and UNIX sockets. Details can be found in the [client configuration guide](https://github.com/redis/node-redis/blob/master/docs/client-configuration.md).

### Example: Indexing and querying JSON documents
### Production usage

Make sure that you have Redis Stack and `node-redis` installed. Import dependencies:
#### Handling errors
Node-Redis provides [multiple events to handle various scenarios](https://github.com/redis/node-redis?tab=readme-ov-file#events), among which the most critical is the `error` event.

```js
import {AggregateSteps, AggregateGroupByReducers, createClient, SchemaFieldTypes} from 'redis';
const client = createClient();
await client.connect();
```
This event is triggered whenever an error occurs within the client.

Create an index.
It is crucial to listen for error events.

```js
try {
await client.ft.create('idx:users', {
'$.name': {
type: SchemaFieldTypes.TEXT,
SORTABLE: true
},
'$.city': {
type: SchemaFieldTypes.TEXT,
AS: 'city'
},
'$.age': {
type: SchemaFieldTypes.NUMERIC,
AS: 'age'
}
}, {
ON: 'JSON',
PREFIX: 'user:'
});
} catch (e) {
if (e.message === 'Index already exists') {
console.log('Index exists already, skipped creation.');
} else {
// Something went wrong, perhaps RediSearch isn't installed...
console.error(e);
process.exit(1);
}
}
```

Create JSON documents to add to your database.
If a client does not register at least one error listener and an error occurs, the system will throw that error, potentially causing the Node.js process to exit unexpectedly.
See [the EventEmitter docs](https://nodejs.org/api/events.html#events_error_events) for more details.

```js
await Promise.all([
client.json.set('user:1', '$', {
"name": "Paul John",
"email": "[email protected]",
"age": 42,
"city": "London"
}),
client.json.set('user:2', '$', {
"name": "Eden Zamir",
"email": "[email protected]",
"age": 29,
"city": "Tel Aviv"
}),
client.json.set('user:3', '$', {
"name": "Paul Zamir",
"email": "[email protected]",
"age": 35,
"city": "Tel Aviv"
}),
]);
```typescript
const client = createClient({
// ... client options
});
// Always ensure there's a listener for errors in the client to prevent process crashes due to unhandled errors
client.on('error', error => {
console.error(`Redis client error:`, error);
});
```

Let's find user 'Paul` and filter the results by age.

```js
let result = await client.ft.search(
'idx:users',
'Paul @age:[30 40]'
);
console.log(JSON.stringify(result, null, 2));
/*
{
"total": 1,
"documents": [
{
"id": "user:3",
"value": {
"name": "Paul Zamir",
"email": "[email protected]",
"age": 35,
"city": "Tel Aviv"
}
}
]
}
*/
```
#### Handling reconnections

Return only the city field.
If network issues or other problems unexpectedly close the socket, the client will reject all commands already sent, since the server might have already executed them.
The rest of the pending commands will remain queued in memory until a new socket is established.
This behaviour is controlled by the `enableOfflineQueue` option, which is enabled by default.

```js
result = await client.ft.search(
'idx:users',
'Paul @age:[30 40]',
{
RETURN: ['$.city']
}
);
console.log(JSON.stringify(result, null, 2));
The client uses `reconnectStrategy` to decide when to attempt to reconnect.
The default strategy is to calculate the delay before each attempt based on the attempt number `Math.min(retries * 50, 500)`. You can customize this strategy by passing a supported value to `reconnectStrategy` option:

/*
{
"total": 1,
"documents": [
{
"id": "user:3",
"value": {
"$.city": "Tel Aviv"
}

1. Define a callback `(retries: number, cause: Error) => false | number | Error` **(recommended)**
```typescript
const client = createClient({
socket: {
reconnectStrategy: function(retries) {
if (retries > 20) {
console.log("Too many attempts to reconnect. Redis connection was terminated");
return new Error("Too many retries.");
} else {
return retries * 500;
}
}
]
}
*/
}
});
client.on('error', error => console.error('Redis client error:', error));
```

Count all users in the same city.
In the provided reconnection strategy callback, the client attempts to reconnect up to 20 times with a delay of `retries * 500` milliseconds between attempts.
After approximately two minutes, the client logs an error message and terminates the connection if the maximum retry limit is exceeded.

```js
result = await client.ft.aggregate('idx:users', '*', {
STEPS: [
{
type: AggregateSteps.GROUPBY,
properties: ['@city'],
REDUCE: [
{
type: AggregateGroupByReducers.COUNT,
AS: 'count'
}
]
}
]
})
console.log(JSON.stringify(result, null, 2));

/*
{
"total": 2,
"results": [
{
"city": "London",
"count": "1"
},
{
"city": "Tel Aviv",
"count": "2"
}
]
}
*/
2. Use a numerical value to set a fixed delay in milliseconds.
3. Use `false` to disable reconnection attempts. This option should only be used for testing purposes.

#### Timeout

await client.quit();
To set a timeout for a connection, use the `connectTimeout` option:
```typescript
const client = createClient({
// setting a 10-second timeout
connectTimeout: 10000 // in milliseconds
});
client.on('error', error => console.error('Redis client error:', error));
```

### Learn more

* [Node-Redis Configuration Options](https://github.com/redis/node-redis/blob/master/docs/client-configuration.md)
* [Redis commands](https://redis.js.org/#node-redis-usage-redis-commands)
* [Programmability](https://redis.js.org/#node-redis-usage-programmability)
* [Clustering](https://redis.js.org/#node-redis-usage-clustering)
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