Adonis Extra Traits

This Package provides multiple useful Traits for Adonis

Table of Contents:

• Usage
• Traits
  • NoTimestamp
  • Singleton
  • CachedAttribute
• ToDo

Usage:

• Install package: npm i @mortz.prk/adonis-extra-trait
• Register with Adonis: add @mortz.prk/adonis-extra-trait to providers array in start/app.js file

Traits:

• NoTimestamp
• Singleton
• CachedAttribute

---

---

NoTimestamp

Intro:

Removes created_at and updated_at field selectively.

This trait is much like NoTimestamp trait provided by Adonis.

Register:

1. Register trait in your model of choice:

   const Model = use('Model');
   
   class Post extends Model {
       static boot() {
           super.boot();
           this.addTrait('@provider:Prk/Traits/NoTimestamp', <option>);
       }
   }

2. Change option:

   option	Required	Type	Default	Description
   createdAt	❌	bool	false	set true if the model has no created_at field
   updatedAt	❌	bool	false	set true if the model has no updated_at field

---

Singleton

Intro:

Make a Model Singleton, which means:

1. You can access last inserted row
2. You can't change any instance after saved in DB

This is useful when you want to keep set of values in DB and also have a history of old values. for example, You may save a configuration in DB

Register:

1. Register trait in your model of choice:

   const Model = use('Model');
   
   class Post extends Model {
       static boot() {
           super.boot();
           this.addTrait('@provider:Prk/Traits/Singleton', <option>);
       }
   }

2. Change option:

   option	Required	Type	Default	Description
   ignoreUpdate	❌	bool	false	set true to allow updating old instances

Usage:

• Model.current will return last inserted row from DB:

  const last = await Post.current;

• update will fail:

  const post1 = await Post.create(data1);
  
  const post2 = await Post.create(data2);
  
  post1.name = 'new Name'
  post1.save() // Will throw Error

  You can disable this behavior by passing ignoreUpdate

---

CachedAttribute

Intro:

Cache last saved values in Redis.

This trait requires Singleton to get registered in the model (must be registered before this one). also Primary Key of model must be an integer value.

Register:

1. Register trait in your model of choice:

   const Model = use('Model');
   
   class Post extends Model {
       static boot() {
           super.boot();
           this.addTrait('@provider:Prk/Traits/Singleton');
           this.addTrait('@provider:Prk/Traits/CachedAttribute', <option>);
       }
   }

2. Change option:

   option	Required	Type	Default	Description
   fields	✅	string[]	undefined	name of attributes to cache
   redis	❌	Redis	use('Redis')	redis provider

3. Register redis custom command by Creating/Changing config/redis.js:

   • add loadScript to file:

      const Env = use('Env');
     
      module.exports = {
          connection: 'local',
          local: {
              host: Env.get('REDIS_HOST'),
              port: Env.get('REDIS_PORT'),
              password: Env.get('REDIS_PASS'),
              db: 0,
              keyPrefix: ''
          },
          loadScript: true // <-- add this line
      };

   • Set value of loadScript based on following table:

     loadScript	Effect
     null	won't register command
     undefined	won't register command
     true	register command for default connection
     'cn'	register command for redis with given connection name
     ['cn1', 'cn2']	register command for redis with given connection names

Usage:

• Model.cached will return last cached attrs from Redis:

  // assuming `fields` for trait is set to ['name', 'isMale']
  const data = {name: 'lorem', lastName: 'ipsum', isMale: false}
  const post = await Post.create(data);
  console.log(await Post.cached)
  // {
  //    name:"lorem",
  //    isMale:false
  // }

  cached will throw an Error if table is empty

• Model.cachedName name of key which is used as key in Redis:

  const Redis = use('Redis')
  // assuming `fields` for trait is set to ['name', 'isMale']
  const data = {name: 'lorem', lastName: 'ipsum', isMale: false}
  const post = await Post.create(data);
  const cacheValue = await Redis.get(Post.cachedName);
  console.log(JSON.pars(cacheValue));
  // {
  //    name:"lorem",
  //    isMale:false
  // }

• Model.warmUp Generates cache, removing old values:

  • use this method to regenerate cache
    • Example: to populate cache in server startup
    • Example: remove old cache value when a transaction rolls back

Known Limitations:

• Redis cluster is not tested and may not work as expected
• Cache will return invalid value, if DB transaction rolls back (run Model.warmUp to fix it for now)

FAQ:

1. How to use another connection for redis:

   Pass Redis.connection('nameOfConnection') to trait option:

   const Model = use('Model');
   const Redis = use('Redis');
   
   class Post extends Model {
       static boot() {
           super.boot();
           this.addTrait('@provider:Prk/Traits/Singleton');
           this.addTrait(
               '@provider:Prk/Traits/CachedAttribute', 
               {fields: ['name'], redis: Redis.connection('anotherName')}
            );
       }
   }

2. I don't want to use Redis provider from Adonis, but an ioredis instance:

   • Pass ioRedis to trait option:

     const Model = use('Model');
     const ioRedis = require('../ioredis'); // <-- this is an ioredis instance
     
     class Post extends Model {
         static boot() {
             super.boot();
             this.addTrait('@provider:Prk/Traits/Singleton');
             this.addTrait(
                 '@provider:Prk/Traits/CachedAttribute', 
                 {fields: ['name'], redis: ioRedis}
              );
         }
     }

   • Register Command in Redis:

     const redisCommandLoader = use('Prk/Helper/RedisCustomCommand');
     const ioRedis = require('../ioredis');
     await redisCommandLoader(ioRedis);

3. I don't want to use neither Redis provider from Adonis nor an ioredis instance:

   • Pass Redis like object to trait option:

     const Model = use('Model');
     const Redis = require('another-redis-lib');
     
     const redis = {
       get: (keyName) => {
           return Redis.getFromCacheMethod(keyName);
       },
       set: (keyName, value) => {
           return Redis.setToCacheMethod(keyName, value);
       },
       evalsha: (hash, numOfKeys, k1,k2,k3,k4) => {
           return Redis.methodToRunCachedScript(hash, numOfKeys, k1,k2,k3,k4);
       },
     };
     class Post extends Model {
         static boot() {
             super.boot();
             this.addTrait('@provider:Prk/Traits/Singleton');
             this.addTrait(
                 '@provider:Prk/Traits/CachedAttribute', 
                 {fields: ['name'], redis: redis}
              );
         }
     }

   • Register Command in Redis:

     const redisCommandLoader = use('Prk/Helper/RedisCustomCommand');
     const {command} = use('Prk/Helper/RedisCustomCommandDetail');
     const Redis = require('another-redis-lib');
     await redisCommandLoader({
         script: (action, command) => await Redis.methodToEvaluateCommand(command)
     });

4. I didn't understand logic of loadScript.

   • short answer:

     CachedAttribute trait uses a lua script internally to cache attributes in Redis. to cache the lua script itself in Redis (for better performance) we have to run a command in Redis.

   • If you are using default config for redis:

     Which is something like this:

     const Env = use('Env');
     
     module.exports = {
       connection: 'local',
       local: {
         host: Env.getOrFail('REDIS_HOST'),
         port: Env.getOrFail('REDIS_PORT'),
         password: null,
         db: 0,
         keyPrefix: ''
       },
       ...
     };

     then you just need to change file to this:

     const Env = use('Env');
     
     module.exports = {
       connection: 'local',
       local: {
         host: Env.getOrFail('REDIS_HOST'),
         port: Env.getOrFail('REDIS_PORT'),
         password: null,
         db: 0,
         keyPrefix: ''
       },
       loadScript: true,
       ...
     };

     now, provider will automatically register command in Redis.

   • If you use Redis provider from Adonis and know what you are doing:

     with a config file like following:

     const Env = use('Env');
     
     module.exports = {
       connection: 'local',
       local: {
         host: Env.getOrFail('LOCAL_REDIS_HOST'),
         port: Env.getOrFail('LOCAL_REDIS_PORT'),
         password: null,
         db: 0,
         keyPrefix: ''
       },
       anotherLocal: {
         host: Env.getOrFail('ANOTHER_REDIS_HOST'),
         port: Env.getOrFail('ANOTHER_REDIS_PORT'),
         password: null,
         db: 0,
         keyPrefix: ''
       },
       againAnotherLocal: {
         host: Env.getOrFail('AGAIN_ANOTHER_REDIS_HOST'),
         port: Env.getOrFail('AGAIN_ANOTHER_REDIS_PORT'),
         password: null,
         db: 0,
         keyPrefix: ''
       },
       ...
     };

     then add loadScript to config, like:

     const Env = use('Env');
     
     module.exports = {
       connection: 'local',
       ...,
       loadScript: <value>,
       ...
     };

     based on <value> you have different behavior:

     1. <value>: null or undefined -> nothing happens
     2. <value>: true -> command registers in LOCAL_REDIS_HOST
     3. <value>: 'anotherLocal' -> command registers in ANOTHER_REDIS_HOST
     4. <value>: ['anotherLocal', 'againAnotherLocal'] -> command registers in ANOTHER_REDIS_HOST and AGAIN_ANOTHER_REDIS_HOST

   • If you use another library to connect with redis:

     import command detail from helper:

     const {command,hash,numOfKeys} = use('Prk/Helper/RedisCustomCommandDetail');

     now you should register script using your library

     const redisClient = require('another-redis-lib');
     redisClient.aMethodWhichLoadsLuaScript(command);

ToDo:

• test for redis cluster
• add badges (test, version, last version of dependencies usage)
• make this a typescript package (!)
• add ci (Travis, Circle or Gitlab)