moleculer-db

Moleculer service to store entities in database.

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

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",
    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));

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.
`excludeFields`	`Array.<String>`	`null`	Exclude fields from list. It must be an `Array`.
`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.

Note: idField does not work with Sequelize adapter as you can freely set your own ID while creating the model.

Actions

`find`

Find entities by query.

Parameters

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

Results

Type: Array.<Object>

List of found entities.

`count`

Get count of entities by query.

Parameters

Property	Type	Default	Description
`search`	`String`	-	Search text.
`searchFields`	`String`, `Array.<String>`	required	Fields list for searching.
`query`	`Object`	-	Query object. Passes to adapter.

Results

Type: Number

Count of found entities.

`list`

List entities by filters and pagination results.

Parameters

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

Results

Type: Object

List of found entities and count with pagination info.

Property	Type	Default	Description
`params`	`Object`	required	Entity to save.

`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`

Get entity by ID.

Parameters

Property	Type	Default	Description
`id`	`any`, `Array.<any>`	required	ID(s) of entity.
`populate`	`String`, `Array.<String>`	required	Field list for populate.
`fields`	`String`, `Array.<String>`	required	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).

`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

Property	Type	Default	Description
`ctx`	`Context`	required
`params`	`Object`	required

`getById`

Get entity(ies) by ID(s).

Parameters

Property	Type	Default	Description
`id`	`any`, `Array.<any>`	required	ID or IDs.
`decoding`	`Boolean`	-	Need to decode IDs.

Results

Type: Object, Array.<Object>

Found entity(ies).

Property	Type	Default
`type`	`String`	required
`json`	`Object`, `Array.<Object>`, `Number`	required
`ctx`	`Context`	required

Property	Type	Default	Description
No input parameters.

Property	Type	Default
`ctx`	`Context`	required
`params`	`Object`	required
`docs`	`Array`, `Object`	required

Property	Type	Default	Description
`entity`	`Object`	required

Property	Type	Default	Description
`id`	`any`	required

Property	Type	Default	Description
`id`	`any`	required

`_find`

Find entities by query.

Parameters

Property	Type	Default	Description
`ctx`	`Context`	required	Context instance.
`params`	`Object`	-	Parameters.

Results

Type: Array.<Object>

List of found entities.

`_count`

Get count of entities by query.

Parameters

Property	Type	Default	Description
`ctx`	`Context`	required	Context instance.
`params`	`Object`	-	Parameters.

Results

Type: Number

Count of found entities.

`_list`

List entities by filters and pagination results.

Parameters

Property	Type	Default	Description
`ctx`	`Context`	required	Context instance.
`params`	`Object`	-	Parameters.

Results

Type: Object

List of found entities and count.

`_insert`

Create many new entities.

Parameters

Property	Type	Default	Description
`ctx`	`Context`	required	Context instance.
`params`	`Object`	-	Parameters.

Results

Type: Object, Array.<Object>

Saved entity(ies).

`_get`

Get entity by ID.

Parameters

Property	Type	Default	Description
`ctx`	`Context`	required	Context instance.
`params`	`Object`	-	Parameters.

Results

Type: Object, Array.<Object>

Found entity(ies).

`_remove`

Remove an entity by ID.

Parameters

Property	Type	Default	Description
`ctx`	`Context`	required	Context instance.
`params`	`Object`	-	Parameters.

Populating

The service supports to populate fields from other services. E.g.: 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, docs, 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"
            });
        }
    }
}

Remove default actions

According to moleculer documentation you can disable an action when override it with false

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

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

    actions: {
        // Disable find default action
        find: false
    }
}