Services - Cache

CrudServices can store single results in a cache.

By default, a basic in-memory (RAM) cache is used.

Configuration

You can provide your own distributed cache, as long as it implements the CrudCache interface.

export interface CrudCache {
    get: (key: string) => Promise<any>;
    set: (key: string, value: any, ttl: number) => Promise<any>;
}

You can provide it globally through the CrudConfigService.

eicrud.config.service.ts

let myCache: CrudCache = ...

@Injectable()
export class MyConfigService extends CrudConfigService {
    constructor(/* ... */) {
        super({ cacheManager: myCache , /* ... */})
    }
    //..
}

Or you can provide it to a specific service.

user.service.ts

let myCache: CrudCache = ...

@Injectable()
export class UserService extends CrudUserService<User> {
        constructor(/* ... */) {
        super( /* ... */, { cacheManager: myCache })
    }
    //..
}

Usage

CrudUserService has several methods that access the cache.

$findOneCached

$findOneCached tries to retrieve the result from the cache using id_field + CrudOptions? as a key. If no result is found, $findOne is called and the result is stored in cache.

Note

When $findOneCached is called through the client, found results are not stored in the cache to prevent users from maliciously filling it. You can disable that behavior with allowClientCacheFilling.

cacheOptions.allowClientCacheFilling = true;

In that case, make sure your cache has a maximum and an eviction strategy in place.

$setCached

$setCached inserts a given entity into the CrudCache.

$deleteCached

$deleteCached removes a given entity into the CrudCache.

Authentication

During authentication, the user is fetched with CrudUserService->$findOneCached.

Note

The CrudCache of CrudUserService has a great impact on your application performance since users are fetched in every authenticated request.

Options

export class CacheOptions {
    TTL = 60 * 12 * 1000; // 12 minutes
    allowClientCacheFilling = false;
}

profile.service.ts

import { CacheOptions } from '@eicrud/core/config';

const cacheOptions = new CacheOptions();

@Injectable()
export class ProfileService extends CrudService<Profile> {
        constructor(/* ... */) {
        super( /* ... */, { cacheOptions })
    }
    //..
}

Use a different cache key

Each CrudService takes an optional cacheField config parameter.

token.service.ts

  constructor(protected moduleRef: ModuleRef) {
    const serviceName = CrudService.getName(Token);
    super(moduleRef, Token, getSecurity(serviceName), { hooks, cacheField: 'token' });
  }

The new field replaces id_field to identify your cached entities ($findOneCached, $setCached...)

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