loopback-example-database

A brief tutorial on using the LoopBack MongoDB connector.Note: This page was generated from the loopback-example-database/README.md.

loopback-example-database

A tutorial for basic database related features.

Overview

Topics covered

Data sources
- Creating
- Configuring
Models
- Creating
Automigration
Instance introspection (Discovery)

Database specific tutorials

Database specific tutorials are on separate branches. The master branch containsthe tutorial for MongoDB.

Branch	Connector
master	MongoDB
mssql	Microsoft SQL Server
mysql	MySQL
oracle	Oracle
postgresql	PostgreSQL

For example, to view the MySQL example:

git clone https://github.com/strongloop/loopback-example-database
cd loopback-example-database
git checkout mysql

Prerequisites

Before starting this tutorial, make sure you have the following installed:

Running the example

git clone https://github.com/strongloop/loopback-example-database
cd loopback-example-database
npm install
npm start

Tutorial - MongoDB

1. Create a new LoopBack app

App info

Name: loopback-example-database
Dir to contain the project: loopback-example-database

lb app loopback-example-database
     _-----_
    |       |    ╭──────────────────────────╮
    |--(o)--|    │  Let's create a LoopBack │
   `---------´   │       application!       │
    ( _´U`_ )    ╰──────────────────────────╯
    /___A___\   /
     |  ~  |
   __'.___.'__
 ´   `  |° ´ Y `
? What's the name of your application? loopback-example-database
? Enter name of the directory to contain the project: loopback-example-database
     info change the working directory to loopback-example-database
? Which version of LoopBack would you like to use? 3.x (current)
? What kind of application do you have in mind? empty-server (An empty LoopBack API, without any c
onfigured models or datasources)

2. Install the LoopBack MongoDB connector

cd loopback-example-database
npm install --save loopback-connector-mongodb

3. Create a data source

Data source info

Data source name: accountDS
Select the connector for accountDS: MongoDB

lb datasource accountDS
... # follow the prompts

This creates a new data source named accountDS that uses the MongoDBconnector.

4. Configure the data source

For the purposes of this example, we will use a preconfigured StrongLoop MongoDBserver. Edit server/datasources.json to set the MongoDB configs:

{
  ...
  "accountDS": {
    "name": "accountDS",
    "connector": "mongodb",
    "host": "demo.strongloop.com",
    "port": 27017,
    "database": "demo",
    "username": "demo",
    "password": "L00pBack"
  }
}

Feel free to use your own local MongoDB instance. Simply change the configsabove to match your own.

5. Create a new model

lb model
... # follow the prompts

Model Info

Model name: Account
Attach Account to: accountDS (mongodb)
Base class: PersistedModel
Expose via REST: Yes
Custom plural form: Leave blank
Properties:
- email
  - String
  - Not required
- createdAt
  - Date
  - Not required
- lastModifiedAt
  - Date
  - Not required

slc loopback:model Account
... # follow the prompts

6. Create the collection with sample data - Automigration

With the account model configured, we can generate the correspondingMongoDB collection using the info from the Account metadata in common/models/account.jsonvia auto-migration.

Start by creating a dir to store general-purpose scripts:

mkdir bin

Inside that dir, create a script named automigrate.js.To create the Account collection and create two sample accounts, run:

node bin/automigrate.js

WARNING

The automigrate function creates a new collection if it doesn’t exist. Ifthe collection already exists, it will be destroyed and it’s data will bedeleted. If you want to keep this data, use autoupdate instead.

You should see:

Created: { email: 'baz@qux.com',
  createdAt: Thu Oct 22 2015 17:58:09 GMT-0700 (PDT),
  lastModifiedAt: Thu Oct 22 2015 17:58:09 GMT-0700 (PDT),
  id: 562986213ea33440575c6588 }
Created: { email: 'foo@bar.com',
  createdAt: Thu Oct 22 2015 17:58:09 GMT-0700 (PDT),
  lastModifiedAt: Thu Oct 22 2015 17:58:09 GMT-0700 (PDT),
  id: 562986213ea33440575c6587 }

If you are using Node 4, it is safe to ignore Swagger: skipping unknown type"ObjectId". This warning will be addressed in a future update.

7. View data using the explorer

Projects scaffolded via slc loopback come with loopback-component-explorerpreconfigured. From the project root, start the server:

node .

Then to view the existing account data, browse to localhost:3000/explorer andclick:

GET /Accounts
Try it out!You should see:

[
  {
    "email": "foo@bar.com",
    "createdAt": "2015-10-23T00:58:09.280Z",
    "lastModifiedAt": "2015-10-23T00:58:09.280Z",
    "id": "562986213ea33440575c6587"
  },
  {
    "email": "baz@qux.com",
    "createdAt": "2015-10-23T00:58:09.280Z",
    "lastModifiedAt": "2015-10-23T00:58:09.280Z",
    "id": "562986213ea33440575c6588"
  }
]

Try out some of the other endpoints to get a feel for how explorer works.

8. Add a script to perform instance instrospection (Discovery)

Discoveryis the process of reverse engineering a LoopBack model from an existing database schema.

The LoopBack MongoDB connector does not support discovery. However, you can useinstance instrospection, which creates a LoopBack model from an existingJavaScript object.

To do this, create a script named instance-introspections.jsin the bin dir. Then run:

node bin/instance-introspection

You should see:

Created: { email: 'bob.doe@ibm.com',
  createdAt: Thu Oct 22 2015 19:38:20 GMT-0700 (PDT),
  lastModifiedAt: Thu Oct 22 2015 19:38:20 GMT-0700 (PDT),
  id: 56299d9d71c7f600719ca39f }