Introduction

Cache the output of a Service function for the specified ttl. For example: Adding @cached(10) as a decorator on a function will cache result of the function for 10 seconds.

Getting Started

1. Installation process

   • Install shared-libraries-nodejs-caching in your application by executing the command below,

     npm install shared-libraries-nodejs-caching

   • Add a file named .babelrc on the root of your application and add the content below,

     {
     "presets": [
         "@babel/preset-env"
     ],
     "plugins": [
         ["@babel/plugin-proposal-decorators", {
         "decoratorsBeforeExport": true
         }]
     ]
     }

2. Usage Add @cached(ttlInSeconds:number) as a decorator to the function you want to cache

   • Adding @cached(10) as mentioned below, as a decorator to the function, will cache the result for 10 seconds

     import { cached } from "shared-libraries-nodejs-caching-abc";
     
     export default class Service1 {
         greet() {
         return 'Hello1';
         }
     
         say(toSay) {
         console.log(toSay)
         return 'The app said ' + toSay
         }
     
         @cached(10)
         getCurrentCities()
         {
         return  [
             {
                 id: 1,
                 name: "New York",
             },
             {
                 id: 2,
                 name: "Berlin",
             },
             {
             id: 3,
             name: "London",
             },
             {
             id: 4,
             name: Date(),
             },
         ];
         }
     }

   • Adding @cached(10) as mentioned below, as a decorator to the class, will cache the results of all the functions in the class for 10 seconds

     import { cached } from "shared-libraries-nodejs-caching-abc";
     
     @cached(10)
     export default class Service1 {
         greet() {
         return 'Hello1';
         }
     
         say(toSay) {
         console.log(toSay)
         return 'The app said ' + toSay
         }
     
         getCurrentCities()
         {
         return  [
             {
                 id: 1,
                 name: "New York",
             },
             {
                 id: 2,
                 name: "Berlin",
             },
             {
             id: 3,
             name: "London",
             },
             {
             id: 4,
             name: Date(),
             },
         ];
         }
     }

Cache Key

The cache key attribute is used to specify which argument passed to the service should be used to compute the cache key. For example, of an agrument with a model below, the field 'kind' can be considered as key for Single key strategy and 'colors' can be used for Multiple key strategy.

class Car {

    kind = "hatch";
    colors = ['red', 'green'];
  }

Key Strategy

Determines how the cache entry keys are computed. There are three available options:

1. Request The Request strategy generates a cache key based on the service's name without requiring a request argument. This suits services without arguments or when arguments don't impact cache validity.

[Cached(5, 'request')]
Task<NoKeyResponse> DoSomethingWithoutKey(NoKeyRequest value, CancellationToken cancellationToken = default);

2. Single The Single strategy uses a specified input argument as the caching key.

[Cached(5, 'single', 'kind')]
Task<SingleKeyResponse> DoSomething(SingleKeyRequest value, CancellationToken cancellationToken = default)

3. Multiple The Multiple strategy allows for a list or an array of input arguments to be used as the caching key.

[Cached(5, 'multiple', 'colors')]
Task<MultiKeyResponse> DoSomethingWithMultiKeys(MultiKeyRequest value, CancellationToken cancellationToken = default)