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Key-Value Store

All Less deployments come with a built in key-value store.

Import the Key-Value Store​

Import kvs from @chuva.io/less.

const { kvs } = require('@chuva.io/less');

Set Value for Key​

The key should be a string. The value can be any primitive (number, object, etc.).

const { kvs } = require('@chuva.io/less');

await kvs.set('MY_KEY', 'This is my value.');

Get Value for Key​

Get a value for a key.

const { kvs } = require('@chuva.io/less');

const my_value = await kvs.get('MY_KEY');

Delete Value and Key​

Delete a key and its value.

const { kvs } = require('@chuva.io/less');

await kvs.delete('MY_KEY');

Subscribe to KVS changes​

The Key-Value Store (KVS) allows you to subscribe to a stream of real-time updates by leveraging Less's Topics/Subscribers (Pub/Sub) feature.

Less Topics Documentation

Read the Less Topics/Subscribers (Pub/Sub) documentation to learn more.

Subscribe to create events​

Create the kvs_created Topic.

mkdir -p less/topics/kvs_created/log
touch less/topics/kvs_created/log/index.js
less/topics/kvs_created/log/index.js
exports.process = async ({ key, new_value }) => {
  console.log(`New item created with key: '${key}' and value: '${new_value}'.`);
}

Here is an example kvs_created event payload:

{
  "key": "artists",
  "new_value": [
    {
      "first_name": "Cesária",
      "last_name": "Évora",
      "dob": "08/27/1941"
    }
  ]
}

Subscribe to update events​

Create the kvs_updated Topic.

mkdir -p less/topics/kvs_updated/log
touch less/topics/kvs_updated/log/index.js
less/topics/kvs_updated/log/index.js
exports.process = async ({ key, old_value, new_value }) => {
  console.log(`Item with with key: '${key}' updated.`);
  console.log(`Old value: ${old_value}.`);
  console.log(`New value: ${new_value}.`);
}

Here is an example kvs_updated event payload:

{
  "key": "artists",
  "new_value": [
    {
      "first_name": "Cesária",
      "last_name": "Évora",
      "dob": "08/27/1941"
    },
    {
      "first_name": "Mayra",
      "last_name": "Andrade",
      "dob": "02/13/1985"
    }
  ],
  "old_value": [
    {
      "first_name": "Cesária",
      "last_name": "Évora",
      "dob": "08/27/1941"
    }
  ]
}

Subscribe delete events​

Create the kvs_deleted Topic.

mkdir -p less/topics/kvs_deleted/log
touch less/topics/kvs_deleted/log/index.js
less/topics/kvs_deleted/log/index.js
exports.process = async ({ key, old_value }) => {
  console.log(`Item with with key: '${key}' deleted.`);
  console.log(`Old value: ${old_value}.`);
}

Here is an example kvs_deleted event payload:

{
  "key": "artists",
  "old_value": [
    {
      "first_name": "Cesária",
      "last_name": "Évora",
      "dob": "08/27/1941"
    }
  ]
}
Less Topics/Subscribers (Pub/Sub) Documentation

Read the Less Topics/Subscribers (Pub/Sub) documentation to learn more.

Time to live​

KVS offers a valuable feature called Time to Live (TTL), which allows you to set an expiration time for an item, leading to its automatic deletion after the specified period. To use this feature, you can add the TTL parameter as a third argument when creating a new item. While the first two parameters are required, the TTL parameter is optional and should be an integer representing the time in seconds until the item expires.

const { kvs } = require('@chuva.io/less');

exports.process = async () => {
  // This is two hours represented in seconds  
  const ttl = 2 * 60 * 60;
  
  // The follow item should be expired within 2 hours after its creation
  await kvs.set('UserName', 'Cesaria', ttl);
}