Database Adapters

Moleculer framework has an official set of DB adapters. Use them to persist your data in a database.

Database per service

Moleculer follows the one database per service pattern. To learn more about this design pattern and its implications check this article.

Features

  • default CRUD actions
  • cached actions
  • pagination support
  • pluggable adapter (NeDB is the default memory adapter for testing & prototyping)
  • official adapters for MongoDB, PostgreSQL, SQLite, MySQL, MSSQL.
  • fields filtering
  • populating
  • encode/decode IDs
  • entity lifecycle events for notifications

Base Adapter NPM version

Moleculer’s default adapter is based on NeDB. Use it to quickly set up and test you prototype.

Only use this adapter for prototyping and testing. When you are ready to go into production simply swap to Mongo, Mongoose or Sequelize adapters as they all implement common Settings, Actions and Methods.

Install

$ npm install moleculer-db --save

Usage

"use strict";

const { ServiceBroker } = require("moleculer");
const DbService = require("moleculer-db");

const broker = new ServiceBroker();

// Create a DB service for `user` entities
broker.createService({
name: "users",

// Mixin DB service into (current) 'users' service
mixins: [DbService],

settings: {
fields: ["_id", "username", "name"]
},

afterConnected() {
// Seed the DB with ˙this.create`
}
});

broker.start()

// Create a new user
.then(() => broker.call("users.create", {
username: "john",
name: "John Doe",
status: 1
}))

// Get all users
.then(() => broker.call("users.find").then(console.log));

// List users with pagination
.then(() => broker.call("users.list", { page: 2, pageSize: 10 }).then(console.log));

// Get a user
.then(() => broker.call("users.get", { id: 2 }).then(console.log));

// Update a user
.then(() => broker.call("users.update", { id: 2, name: "Jane Doe" }).then(console.log));

// Delete a user
.then(() => broker.call("users.remove", { id: 2 }).then(console.log));

More examples can be found on GitHub

Settings

All DB adapters share a common set of settings:

Property Type Default Description
idField String required Name of ID field.
fields Array.<String> null Field filtering list. It must be an Array. If the value is null or undefined doesn’t filter the fields of entities.
populates Array null Schema for population. Read more.
pageSize Number required Default page size in list action.
maxPageSize Number required Maximum page size in list action.
maxLimit Number required Maximum value of limit in find action. Default: -1 (no limit)
entityValidator Object, function null Validator schema or a function to validate the incoming entity in create & ‘insert’ actions.

Actions

DB adapters also implement CRUD operations. These actions are public methods and can be called by other services.

find Cached action

Find entities by query.

Parameters

Property Type Default Description
populate Array.<String> - Populated fields.
fields Array.<String> - Fields filter.
limit Number required Max count of rows.
offset Number required Count of skipped rows.
sort String required Sorted fields.
search String required Search text.
searchFields String required Fields for searching.
query Object required Query object. Passes to adapter.

Results

Type: Array.<Object> - List of found entities.

count Cached action

Get count of entities by query.

Parameters

Property Type Default Description
search String required Search text.
searchFields String required Fields list for searching.
query Object required Query object. Passes to adapter.

Results

Type: Number - Count of found entities.

list Cached action

List entities by filters and pagination results.

Parameters

Property Type Default Description
populate Array.<String> - Populated fields.
fields Array.<String> - Fields filter.
page Number required Page number.
pageSize Number required Size of a page.
sort String required Sorted fields.
search String required Search text.
searchFields String required Fields for searching.
query Object required Query object. Passes to adapter.

Results

Type: Object - List of found entities and count.

create

Create a new entity.

Parameters

Property Type Default Description
- - - -

No input parameters.

Results

Type: Object - Saved entity.

insert

Create many new entities.

Parameters

Property Type Default Description
entity Object - Entity to save.
entities Array.<Object> - Entities to save.

Results

Type: Object, Array.<Object> - Saved entity(ies).

get Cached action

Get entity by ID.

Parameters
Property Type Default Description
id any, Array.<any> required ID(s) of entity.
populate Array.<String> - Field list for populate.
fields Array.<String> - Fields filter.
mapping Boolean - Convert the returned Array to Object where the key is the value of id.

Results

Type: Object, Array.<Object> - Found entity(ies).

update

Update an entity by ID.

After update, clear the cache & call lifecycle events.

Parameters

Property Type Default Description
- - - -

No input parameters.

Results

Type: Object - Updated entity.

remove

Remove an entity by ID.

Parameters

Property Type Default Description
id any required ID of entity.

Results

Type: Number - Count of removed entities.

Methods

DB adapters also has a set of helper methods

getById

Get entity(ies) by ID(s).

Parameters

Property Type Default Description
id String, Number, Array required ID or IDs.
decoding Boolean required Need to decode IDs.

Results

Type: Object, Array.<Object> - Found entity(ies).

clearCache

Clear cached entities

Parameters

Property Type Default Description
- - - -

No input parameters.

Results

Type: Promise

encodeID

Encode ID of entity.

Parameters

Property Type Default Description
id any required -

Results

Type: any

decodeID

Decode ID of entity.

Parameters

Property Type Default Description
id any required -

Results

Type: any

Populating

The service allows you to easily populate fields from other services. For exapmle: If you have an author field in post entity, you can populate it with users service by ID of author. If the field is an Array of IDs, it will populate all entities via only one request

Example of populate schema

broker.createService({
name: "posts",
mixins: [DbService],
settings: {
populates: {
// Shorthand populate rule. Resolve the `voters` values with `users.get` action.
"voters": "users.get",

// Define the params of action call. It will receive only with username & full name of author.
"author": {
action: "users.get",
params: {
fields: "username fullName"
}
},

// Custom populator handler function
"rate"(ids, rule, ctx) {
return Promise.resolve(...);
}
}
}
});

// List posts with populated authors
broker.call("posts.find", { populate: ["author"]}).then(console.log);

The populate parameter is available in find, list and get actions.

Lifecycle entity events

There are 3 lifecycle entity events which are called when entities are manipulated.

broker.createService({
name: "posts",
mixins: [DbService],
settings: {},

afterConnected() {
this.logger.info("Connected successfully");
},

entityCreated(json, ctx) {
this.logger.info("New entity created!");
},

entityUpdated(json, ctx) {
// You can also access to Context
this.logger.info(`Entity updated by '${ctx.meta.user.name}' user!`);
},

entityRemoved(json, ctx) {
this.logger.info("Entity removed", json);
},
});

Please note! If you manipulate multiple entities (updateMany, removeMany), the json parameter will be a Number instead of entities!

Extend with custom actions

Naturally you can extend this service with your custom actions.

const DbService = require("moleculer-db");

module.exports = {
name: "posts",
mixins: [DbService],

settings: {
fields: ["_id", "title", "content", "votes"]
},

actions: {
// Increment `votes` field by post ID
vote(ctx) {
return this.adapter.updateById(ctx.params.id, { $inc: { votes: 1 } });
},

// List posts of an author
byAuthors(ctx) {
return this.find({
query: {
author: ctx.params.authorID
},
limit: ctx.params.limit || 10,
sort: "-createdAt"
});
}
}
}

Mongo Adapter NPM version

This adapter is based on MongoDB.

Install

$ npm install moleculer-db moleculer-db-adapter-mongo --save
Dependencies

To use this adapter you need to install MongoDB on you system.

Usage

"use strict";

const { ServiceBroker } = require("moleculer");
const DbService = require("moleculer-db");
const MongoDBAdapter = require("moleculer-db-adapter-mongo");

const broker = new ServiceBroker();

// Create a Mongoose service for `post` entities
broker.createService({
name: "posts",
mixins: [DbService],
adapter: new MongoDBAdapter("mongodb://localhost/moleculer-demo"),
collection: "posts"
});


broker.start()
// Create a new post
.then(() => broker.call("posts.create", {
title: "My first post",
content: "Lorem ipsum...",
votes: 0
}))

// Get all posts
.then(() => broker.call("posts.find").then(console.log));

Options

Example with connection URI

new MongoDBAdapter("mongodb://localhost/moleculer-db")

Example with connection URI & options

new MongoDBAdapter("mongodb://db-server-hostname/my-db", {
keepAlive: 1
})

More MongoDB examples can be found on GitHub

Mongoose Adapter NPM version

This adapter is based on Mongoose.

Install

$ npm install moleculer-db moleculer-db-adapter-mongoose mongoose --save
Dependencies

To use this adapter you need to install MongoDB on you system.

Usage

"use strict";

const { ServiceBroker } = require("moleculer");
const DbService = require("moleculer-db");
const MongooseAdapter = require("moleculer-db-adapter-mongoose");
const mongoose = require("mongoose");

const broker = new ServiceBroker();

// Create a Mongoose service for `post` entities
broker.createService({
name: "posts",
mixins: [DbService],
adapter: new MongooseAdapter("mongodb://localhost/moleculer-demo"),
model: mongoose.model("Post", mongoose.Schema({
title: { type: String },
content: { type: String },
votes: { type: Number, default: 0}
}))
});


broker.start()
// Create a new post
.then(() => broker.call("posts.create", {
title: "My first post",
content: "Lorem ipsum...",
votes: 0
}))

// Get all posts
.then(() => broker.call("posts.find").then(console.log));

Options

Example with connection URI

new MongooseAdapter("mongodb://localhost/moleculer-db")

Example with URI and options

new MongooseAdapter("mongodb://db-server-hostname/my-db", {
user: process.env.MONGO_USERNAME,
pass: process.env.MONGO_PASSWORD
keepAlive: true
})

More Mongoose examples can be found on GitHub

Sequelize Adapter NPM version

SQL adapter (Postgres, MySQL, SQLite & MSSQL) for Moleculer DB service with Sequelize.

Install

$ npm install moleculer-db-adapter-sequelize --save

You have to install additional packages for your database server:

# For SQLite
$ npm install sqlite3 --save

# For MySQL
$ npm install mysql2 --save

# For PostgreSQL
$ npm install pg pg-hstore --save

# For MSSQL
$ npm install tedious --save

Usage

"use strict";

const { ServiceBroker } = require("moleculer");
const DbService = require("moleculer-db");
const SqlAdapter = require("moleculer-db-adapter-sequelize");
const Sequelize = require("sequelize");

const broker = new ServiceBroker();

// Create a Sequelize service for `post` entities
broker.createService({
name: "posts",
mixins: [DbService],
adapter: new SqlAdapter("sqlite://:memory:"),
model: {
name: "post",
define: {
title: Sequelize.STRING,
content: Sequelize.TEXT,
votes: Sequelize.INTEGER,
author: Sequelize.INTEGER,
status: Sequelize.BOOLEAN
},
options: {
// Options from http://docs.sequelizejs.com/manual/tutorial/models-definition.html
}
},
});


broker.start()
// Create a new post
.then(() => broker.call("posts.create", {
title: "My first post",
content: "Lorem ipsum...",
votes: 0
}))

// Get all posts
.then(() => broker.call("posts.find").then(console.log));

Options

Every constructor arguments are passed to the Sequelize constructor. Read more about Sequelize connection.

Example with connection URI

new SqlAdapter("postgres://user:pass@example.com:5432/dbname");

Example with connection options

new SqlAdapter('database', 'username', 'password', {
host: 'localhost',
dialect: 'mysql'|'sqlite'|'postgres'|'mssql',

pool: {
max: 5,
min: 0,
idle: 10000
},

// SQLite only
storage: 'path/to/database.sqlite'
});

More Sequelize examples can be found on GitHub