Page Contents

loopback-example-database

A tutorial for basic database related features.

Overview
Prerequisites
Running the example
Tutorial - Oracle

Overview

Topics covered

Data sources
- Creating
- Configuring
Models
- Creating
Automigration
Discovery

Database specific tutorials

Database specific tutorials are on separate branches. The master branch contains the 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:

Node
LoopBack CLI tools; see lb

Running the example

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

Tutorial - Oracle

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
... # follow the prompts

2. Install the LoopBack Oracle connector

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

Automatic PATH modification

⚠️ DEPRECATED loopback 1.x feature During installation, you will see:
...
---------------------------------------------------------------------------
The node-oracle module and the Oracle specific libraries have been
installed in /Users/sh/repos/loopback-example-database/node_modules/loopback-connector-oracle/node_modules/loopback-oracle-installer.

The default bashrc (/etc/bashrc) or user's bash_profile (~/.bash_profile)
paths have been modified to use this path. If you use a shell other than
bash, please remember to set the DYLD_LIBRARY_PATH prior to using node.

Example:
  $ export DYLD_LIBRARY_PATH=":/Users/$USER/repos/loopback-example-database/node_modules/loopback-connector-oracle/node_modules/instantclient:/Users/$USER/repos/loopback-example-database/node_modules/loopback-connector-oracle/node_modules/instantclient"
...
This is a DEPRECATED feature from LoopBack 1.x (we will remove this message in a future update. Due to concerns raised in the past regarding the “invasiveness” of automatic PATH modification, we now generate a file in your home directory named strong-oracle.rc instead. This file is meant to be sourced into your startup file (.bashrc, .bash_profile, etc) manually.

Add the following to your startup file (.bashrc, .bash_profile, etc)

source $HOME/strong-oracle.rc

3. Create a data source

Data source info

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

lb datasource accountDS
... # follow the prompts

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

4. Configure the data source

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

{
  ...
  "accountDS": {
    "name": "accountDS",
    "connector": "oracle",
    "host": "demo.strongloop.com",
    "port": 5432,
    "database": "demo",
    "username": "demo",
    "password": "L00pBack"
  }
}

Feel free to use your own local Oracle instance. Simply change the configs above to match your own.

5. Create a new model

Model Info

Model name: Account
Attach Account to: accountDS (oracle)
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

lb model Account
... # follow the prompts

6. Create the collection with sample data - Automigration

With the account model configured, we can generate the corresponding Oracle table 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

WARNING

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

You should see:

Created: { email: 'john.doe@ibm.com',
  createdAt: Mon Oct 26 2015 15:56:30 GMT-0700 (PDT),
  lastModifiedAt: Mon Oct 26 2015 15:56:30 GMT-0700 (PDT),
  id: 1 }
Created: { email: 'jane.doe@ibm.com',
  createdAt: Mon Oct 26 2015 15:56:30 GMT-0700 (PDT),
  lastModifiedAt: Mon Oct 26 2015 15:56:30 GMT-0700 (PDT),
  id: 2 }

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": "john.doe@ibm.com",
    "createdAt": "2015-10-26T23:03:19.000Z",
    "lastModifiedAt": "2015-10-26T23:03:19.000Z",
    "id": 1
  },
  {
    "email": "jane.doe@ibm.com",
    "createdAt": "2015-10-26T23:03:19.000Z",
    "lastModifiedAt": "2015-10-26T23:03:19.000Z",
    "id": 2
  }
]

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

8. Add a script to perform discover the database schema

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

Create a script name discover-schema.js. Then run this script to discover the schema from the existing Account table:

node bin/discover-schema

You should see:

{
  "name": "Account",
  "options": {
    "idInjection": false,
    "oracle": {
      "schema": "DEMO",
      "table": "ACCOUNT"
    }
  },
  "properties": {
    "email": {
      "type": "String",
      "required": false,
      "length": 1024,
      "precision": null,
      "scale": null,
      "oracle": {
        "columnName": "EMAIL",
        "dataType": "VARCHAR2",
        "dataLength": 1024,
        "dataPrecision": null,
        "dataScale": null,
        "nullable": "Y"
      }
    },
    "createdat": {
      "type": "Date",
      "required": false,
      "length": 7,
      "precision": null,
      "scale": null,
      "oracle": {
        "columnName": "CREATEDAT",
        "dataType": "DATE",
        "dataLength": 7,
        "dataPrecision": null,
        "dataScale": null,
        "nullable": "Y"
      }
    },
    "lastmodifiedat": {
      "type": "Date",
      "required": false,
      "length": 7,
      "precision": null,
      "scale": null,
      "oracle": {
        "columnName": "LASTMODIFIEDAT",
        "dataType": "DATE",
        "dataLength": 7,
        "dataPrecision": null,
        "dataScale": null,
        "nullable": "Y"
      }
    },
    "id": {
      "type": "Number",
      "required": true,
      "length": 22,
      "precision": null,
      "scale": null,
      "id": 1,
      "oracle": {
        "columnName": "ID",
        "dataType": "NUMBER",
        "dataLength": 22,
        "dataPrecision": null,
        "dataScale": null,
        "nullable": "N"
      }
    }
  }
}

Notice the string params for discoverSchema are capitalized.

9. Add a script to discover and build models

When retrieving the scheme is not enough, you can discover and build LoopBack models in one step.

Create a sript named discover-and-build-models.js. Then run:

node bin/discover-and-build-models

You should see:

[ { email: 'john.doe@ibm.com',
    createdat: Fri Oct 23 2015 17:39:50 GMT-0700 (PDT),
    lastmodifiedat: Fri Oct 23 2015 17:39:50 GMT-0700 (PDT),
    id: 1 },
  { email: 'jane.doe@ibm.com',
    createdat: Fri Oct 23 2015 17:39:50 GMT-0700 (PDT),
    lastmodifiedat: Fri Oct 23 2015 17:39:50 GMT-0700 (PDT),
    id: 2 } ]

See the official docs for more info.

More LoopBack examples