loopback-example-database

⚠️ This LoopBack 3 example project is no longer maintained. Please refer to LoopBack 4 Examples instead. ⚠️

A tutorial for basic database related features.

• Overview
• Prerequisites
• Running the example
• Tutorial - MongoDB

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 contains the tutorial for MongoDB.

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:

• Node
• NPM
• StrongLoop Controller

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 MongoDB connector.

4. Configure the data source

For the purposes of this example, we will use a preconfigured StrongLoop MongoDB server. 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 configs above 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 corresponding MongoDB collection using the info from the Account metadata in common/models/account.json via 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

You should see:

Created: { email: '[email protected]',
  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: '[email protected]',
  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-explorer preconfigured. From the project root, start the server:

node .

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

• GET /Accounts
• Try it out!

You should see:

[
  {
    "email": "[email protected]",
    "createdAt": "2015-10-23T00:58:09.280Z",
    "lastModifiedAt": "2015-10-23T00:58:09.280Z",
    "id": "562986213ea33440575c6587"
  },
  {
    "email": "[email protected]",
    "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)

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

The LoopBack MongoDB connector does not support discovery. However, you can use instance instrospection, which creates a LoopBack model from an existing JavaScript object.

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

node bin/instance-introspection

You should see:

Created: { email: '[email protected]',
  createdAt: Thu Oct 22 2015 19:38:20 GMT-0700 (PDT),
  lastModifiedAt: Thu Oct 22 2015 19:38:20 GMT-0700 (PDT),
  id: 56299d9d71c7f600719ca39f }

See the official docs for more info.

More LoopBack examples