Caching is nut a problem!

Features

✅ HTTP Caching ✅ Local Storage Support ✅ Handles Simultaneous Requests ✅ Automatic & Manual Cache Busting ✅ Hackable

A flexible and straightforward library that caches HTTP requests in Angular

Installation

$ npm install @ngneat/cashew

Usage

Inject the HttpCacheInterceptorModule module along with HttpClientModule into you root module:

import { NgModule } from '@angular/core';
import { HttpClientModule } from '@angular/common/http';
import { HttpCacheInterceptorModule } from '@ngneat/cashew';

@NgModule({
  imports: [HttpClientModule, HttpCacheInterceptorModule.forRoot()],
  bootstrap: [AppComponent]
})
export class AppModule {}

And you're done! Now, when using Angular HttpClient, you can pass the withCache function as context, and it'll cache the response:

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';
import { withCache } from '@ngneat/cashew';

@Injectable()
export class UsersService {
  constructor(private http: HttpClient) {}

  getUsers() {
    return this.http.get('api/users', {
      context: withCache()
    });
  }
}

It's as simple as that.

Local Storage

By default, caching is done to app memory. To switch to using local storage instead simply add:

import { HttpCacheInterceptorModule, useHttpCacheLocalStorage } from '@ngneat/cashew';

@NgModule({
  imports: [HttpClientModule, HttpCacheInterceptorModule.forRoot()],
  providers: [useHttpCacheLocalStorage],
  bootstrap: [AppComponent]
})
export class AppModule {}

To your AppModule providers list. Note that ttl will also be calculated via local storage in this instance.

Config Options

Using the library, you might need to change the default behavior of the caching mechanism. You could do that by passing a configuration (a partial HttpCacheConfig object) to the static forRoot method of the HttpCacheInterceptorModule module.

{ provide: HTTP_CACHE_CONFIG, useValue: cashewConfig(config) }

Let's go over each of the configuration options:

strategy

Defines the caching behavior. The library supports two different strategies:

• explicit (default) - only caches API requests that explicitly use the withCache function
• implicit - caches API requests that are of type GET and the response type is JSON. You can change this behavior by overriding the HttpCacheGuard provider. (See the Hackable section)

HttpCacheInterceptorModule.forRoot({
  strategy: 'explicit'
});

localStorageKey

When using local storage for caching, this defines the key where the cache is stored (for ttl - with the "Ttl" suffix): (defaults to 'httpCache')

HttpCacheInterceptorModule.forRoot({
  localStorageKey: string
});

ttl

Define the cache TTL (time to live) in milliseconds: (defaults to one hour)

HttpCacheInterceptorModule.forRoot({
  ttl: number
});

responseSerializer

By default, the registry returns the original response object. It can be dangerous if, for some reason, you mutate it. To change this behavior, you can clone the response before getting it:

HttpCacheInterceptorModule.forRoot({
  responseSerializer(body) {
    return cloneDeep(body);
  }
});

API

WithCache

Currently, there is no way in Angular to pass metadata to an interceptor. The withCache function uses the params object to pass the config and removes it afterward in the interceptor. The function receives four optional params that are postfixed with a $ sign so it'll not conflicts with others:

• cache - Whether to cache the request (defaults to true)
• ttl - TTL that will override the global
• key - Custom key. (defaults to the request URL including any query params)
• bucket - The bucket in which we save the keys

@Injectable()
export class UsersService {
  constructor(private http: HttpClient) {}

  getUsers() {
    return this.http.get(
      'api/users',
      { 
        context: withCache({
          withCache: false,
          ttl: 40000,
          key: 'yourkey'
      })}
    );
  }
}

CacheManager

The CacheManager provider, exposes an API to update and query the cache registry:

• get<T>(key: string): HttpResponse<T> - Get the HttpResponse from the cache
• has(key: string) - Returns a boolean indicates whether the provided key exists in the cache
• set(key: string, body: any, { ttl, bucket }) - Set manually a new entry in the cache
• delete(key: string | CacheBucket) - Delete from the cache

CacheBucket

CacheBucket can be useful when we need to buffer multiple requests and invalidate them at some point. For example:

import { withCache, CacheBucket } from '@ngneat/cashew';

@Injectable()
export class TodosService {
  todosBucket = new CacheBucket();

  constructor(private http: HttpClient, private manager: HttpCacheManager) {}

  getTodo(id) {
    return this.http.get(
      `todos/${id}`,
      {
        context: withCache({
          bucket: this.todosBucket
        })
      }
    );
  }

  invalidateTodos() {
    this.manager.delete(this.todosBucket);
  }
}

Now when we call the invalidateTodos method, it'll automatically delete all the ids that it buffered. CacheBucket also exposes the add, has, delete, and clear methods.

Hack the Library

• HttpCacheStorage - The storage to use: (defaults to in-memory storage)

abstract class HttpCacheStorage {
  abstract has(key: string): boolean;
  abstract get(key: string): HttpResponse<any>;
  abstract set(key: string, response: HttpResponse<any>): void;
  abstract delete(key?: string): void;
}

• KeySerializer - Generate the cache key based on the request: (defaults to request.urlWithParams)

export abstract class KeySerializer {
  abstract serialize(request: HttpRequest): string;
}

• HttpCacheGuard - When using the implicit strategy it first verifies that canActivate is truthy:

export abstract class HttpCacheGuard {
  abstract canActivate(request: HttpCacheHttpRequestRequest): boolean;
}

It defaults to request.method === 'GET' && request.responseType === 'json'.

• TTLManager - A class responsible for managing the requests TTL:

abstract class TTLManager {
  abstract isValid(key: string): boolean;
  abstract set(key: string, ttl?: number): void;
  abstract delete(key?: string): void;
}

Contributors ✨

Thanks go to these wonderful people (emoji key):

This project follows the all-contributors specification. Contributions of any kind welcome!