Repository Caching

Caching is crucial when it comes to performance. Warlock provides a simple way to cache your repositories.

Prerequisites

Make sure that you're already Configured Cache and it is activated.

Introduction

The concept here is simple, the repository will fetch data either from the cache or get a fresh copy from the database then cache it, the most important that Warlock will clear the cache each time an update occurred to the attached model either by creating, updating, or deleting a model, this will give us the most recent data and make sure the data in the cache are persistent.

Usage

Every method in Repository listing has a corresponding method suffixed with cached, for example the list cache method is listCached, the all method has allCached, it's the same for the rest of the methods.

Available methods

Here are the available cache methods:

• listCached
• allCached
• listActiveCached
• getCached
• getActiveCached
• oldestCached
• oldestActiveCached
• latestCached
• latestActiveCached
• firstCached
• firstActiveCached
• lastCached
• lastActiveCached

Disable Repository Caching

To disable the cache even if it is activated in the app, set isCacheable property to false:

src/app/users/repositories/users-repository.ts

import {
  FilterByOptions,
  RepositoryManager,
  RepositoryOptions,
} from "@mongez/warlock";
import { User } from "../models/user";

export class UsersRepository extends RepositoryManager<User> {
  /**
   * {@inheritDoc}
   */
  public model = User;

  /**
   * Whether to enable or disable cache
   */
  public isCacheable = false;
}

Set cache driver

By default the cache driver of the repository will be the Cache Manager, however, you can set a different cache driver for the repository by setting the cacheDriverName property to the desired cache:

src/app/users/repositories/users-repository.ts

import {
  FilterByOptions,
  RepositoryManager,
  RepositoryOptions,
} from "@mongez/warlock";
import { User } from "../models/user";

export class UsersRepository extends RepositoryManager<User> {
  /**
   * {@inheritDoc}
   */
  public model = User;

  /**
   * The cache driver to use
   */
  public cacheDriverName = "redis";
}

This will change the cache driver to redis instead of the default cache driver.

Clear repository cache

Each repository has its own namespace, which is repositories followed by the model's collection name, in that sense if we want to clear the entire cache related to the repository, then call clearCache method will do the job:

src/app/main.ts

import { usersRepository } from "./users/repositories/users-repository";

usersRepository.clearCache();

tip

The cache is automatically cleared whenever a model is created, updated, or deleted.

Manually cache data

This could be useful if you're going to implement a custom list method and you want to cache the data, for example, let's fetch and cache all male users:

src/app/users/repositories/users-repository.ts

import {
  FilterByOptions,
  RepositoryManager,
  RepositoryOptions,
} from "@mongez/warlock";
import { User } from "../models/user";

export class UsersRepository extends RepositoryManager<User> {
  /**
   * {@inheritDoc}
   */
  public model = User;

  /**
   * List all male users
   */
  public async allMale(options: RepositoryOptions) {
    // generate cache key for the list method
    const cacheKey = this.cacheKey("male", options);

    // check if the data is already cached
    const users = await this.cacheDriver.get(cacheKey);

    if (users) {
      // if so then return the cached data but map it into list of models first
      return this.mapModels(users);
    }

    // if we reached here then the data is not cached yet, so we need to fetch it from database first
    const maleUsers = await this.allActive({
      gender: "male",
    });

    // cache the data
    // please note that models can not be serialized, thus we need to store only the document data itself
    // we don't need to await the cache driver to finish caching the data so we will not add the await keyword
    this.cacheDriver.set(
      cacheKey,
      maleUsers.map((user) => user.data)
    );

    // return the list of models
    return maleUsers;
  }
}

Let's break down the code above:

• First we generate a cache key for the list method, it's important to use cacheKey method to link the cache to the repository (needed for recaching or clearing the cache) the cacheKey method takes a cache key, and optionally list of options that will serialized to be appended to the cache key.
• Then we check if the data is already cached, if so then we return the cached data but first we need to map it into list of models.
• If the data is not cached yet, then we fetch it from the database.
• Then we cache the data, please note that models can not be serialized, thus we need to store only the document data itself.
• Finally we return the list of models.

We can also use the cacheAll method, that will do all the dirty job for us:

src/app/users/repositories/users-repository.ts

import {
  FilterByOptions,
  RepositoryManager,
  RepositoryOptions,
} from "@mongez/warlock";
import { User } from "../models/user";

export class UsersRepository extends RepositoryManager<User> {
  /**
   * {@inheritDoc}
   */
  public model = User;

  /**
   * List all male users
   */
  public allMale(options: RepositoryOptions) {
    return this.cacheAll({
      ...options,
      gender: "male",
    });
  }
}

Cache list

The cacheAll method will cache the list of models based on the given options without pagination, it will return direct documents list, if you want to cache the list with pagination, then use cacheList method:

src/app/users/repositories/users-repository.ts

import {
  FilterByOptions,
  RepositoryManager,
  RepositoryOptions,
} from "@mongez/warlock";
import { User } from "../models/user";

export class UsersRepository extends RepositoryManager<User> {
  /**
   * {@inheritDoc}
   */
  public model = User;

  /**
   * List all male users
   */
  public allMale(options: RepositoryOptions) {
    return this.cacheList({
      ...options,
      gender: "male",
    });
  }
}

This will return an object contains documents and paginationInfo properties, the documents property contains the list of documents, and the paginationInfo contains the pagination information.

Expire time

In either cacheAll or cacheList we can set the amount of time to expire after (AKA TTL), in this case, we pass to the object expiresAfter key:

src/app/users/repositories/users-repository.ts

import {
  FilterByOptions,
  RepositoryManager,
  RepositoryOptions,
} from "@mongez/warlock";
import { User } from "../models/user";

export class UsersRepository extends RepositoryManager<User> {
  /**
   * {@inheritDoc}
   */
  public model = User;

  /**
   * List all male users
   */
  public allMale(options: RepositoryOptions) {
    return this.cacheList({
      ...options,
      gender: "male",
      expiresAfter: 60 * 60 * 24, // 24 hours
    });
  }
}

note

Please note that the expiresAfter value is in seconds.

Purging the cache

Purging the cache with fetching means if the list is cached then it will be returned from the cache and it will be deleted after fetching, also if it is set to true, then the method will not cache the list if it wast not in the cache.

Cache model

To cache a single model, use cacheModel, it takes an instance of a model and cache it's data.