loopback-connector-oracle

Oracle is an object-relational database management system produced by Oracle Corporation. The loopback-connector-oracle module is the Oracle connector for the LoopBack framework based on the node-oracledb module.

Prerequisites

Node.js: The Oracle connector requires Node.js version 6.x and up.

Windows: On 32-bit Windows systems, you must use the 32-bit version of Node.js. On 64-bit Windows systems, you must use the 64-bit version of Node.js. For more information, see Node-oracledb Installation on Windows.

Oracle: The Oracle connector requires Oracle client libraries 11.2+ and can connect to Oracle Database Server 9.2+.

Installation

Before installing this module, please follow instructions at https://oracle.github.io/node-oracledb/INSTALL.html
to make sure all the prerequisites are satisfied.

In your application root directory, enter this command to install the connector:

``shell
$ npm install loopback-connector-oracle --save
`

If you create a Oracle data source using the data source generator as described below, you don’t have to do this, since the generator will run npm install for you.

The libaio library is required on Linux systems:

On Ubuntu/Debian, get it with this command:

`
sudo apt-get install libaio1
`

On Fedora/CentOS/RHEL, get it with this command:

`
sudo yum install libaio
`

Creating an Oracle data source

Use the Data source generator to add a Oracle data source to your application.
The generator will prompt for the database server hostname, port, and other settings
required to connect to a Oracle database. It will also run the npm install command above for you.

The entry in the application's /server/datasources.json will look like this:

{% include code-caption.html content="/server/datasources.json" %}
`javascript
"mydb": {
"name": "mydb",
"connector": "oracle",
"tns": "demo",
"host": "myserver",
"port": 3306,
"database": "mydb",
"password": "mypassword",
"user": "admin"
}
`

Edit datasources.json to add any other additional properties that you require.

Connector properties

The connector properties depend on naming methods you use for the Oracle database.
LoopBack supports three naming methods:

* Easy connect: host/port/database.
* Local naming (TNS): alias to a full connection string that can specify all the attributes that Oracle supports.
* Directory naming (LDAP): directory for looking up the full connection string that can specify all the attributes that Oracle supports.

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Easy Connect is the simplest form that provides out-of-the-box TCP/IP connectivity to databases.
The data source then has the following settings.

For example:

{% include code-caption.html content="/server/datasources.json" %}
`javascript
{
"demoDB": {
"connector": "oracle",
"host": "oracle-demo.strongloop.com",
"port": 1521,
"database": "XE",
"username": "demo",
"password": "L00pBack"
}
}
`

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Both local and directory naming require that you place configuration files in a TNS admin directory, such as /oracle/admin.

sqlnet.ora

This specifies the supported naming methods; for example:

`
NAMES.DIRECTORY_PATH=(LDAP,TNSNAMES,EZCONNECT)
`

nsnames.ora

This maps aliases to connection stringsl for example:

`
demo1=(DESCRIPTION=(CONNECT_DATA=(SERVICE_NAME=))(ADDRESS=(PROTOCOL=TCP)(HOST=demo.strongloop.com)(PORT=1521)))
`

ldap.ora

This configures the LDAP server.

`
DIRECTORY_SERVERS=(localhost:1389)
DEFAULT_ADMIN_CONTEXT="dc=strongloop,dc=com"
DIRECTORY_SERVER_TYPE=OID
`

#### Set up TNS_ADMIN environment variable

For the Oracle connector to pick up the configurations, you must set the environment variable 'TNS_ADMIN' to the directory containing the .ora files.

`
export TNS_ADMIN=
`

Now you can use either the TNS alias or LDAP service name to configure a data source:

`javascript
var ds = loopback.createDataSource({
"tns": "demo", // The tns property can be a tns name or LDAP service name
"username": "demo",
"password": "L00pBack"
});
`

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For example,

{% include code-caption.html content="/server/datasources.json" %}
`javascript
{
"demoDB": {
"connector": "oracle",
"minConn":1,
"maxConn":5,
"incrConn":1,
"timeout": 10,
...
}
}
`

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If you encounter this error:

`
Error: ORA-24408: could not generate unique server group name
`

Then the Oracle 11g client requires an entry with your hostname pointing to
127.0.0.1.

To resolve:

Get your hostname. Check your hostname by running this command (for example, if your machine's name is "earth"):

`
$ hostname
earth
`

Update /etc/hosts and map 127.0.0.1 to your hostname "earth":

`
...
127.0.0.1 localhost earth
...
`

Verify the fix. Run the example in examples/app.js:

`
$ node examples/app.js
`

For more information, see StackOverflow question.

Model properties

An Oracle model definition consists of the following properties:

* name: Name of the model, by default, it's the camel case of the table.
* options: Model-level operations and mapping to Oracle schema/table.
* properties: Property definitions, including mapping to Oracle column.

{% include code-caption.html content="/common/models/model.json" %}
`javascript
{
"name":"Inventory",
"options":{
"idInjection":false,
"oracle":{
"schema":"STRONGLOOP",
"table":"INVENTORY"
}
},
"properties":{
"productId":{
"type":"String",
"required":true,
"length":20,
"id":1,
"oracle":{
"columnName":"PRODUCT_ID",
"dataType":"VARCHAR2",
"dataLength":20,
"nullable":"N"
}
},
"locationId":{
"type":"String",
"required":true,
"length":20,
"id":2,
"oracle":{
"columnName":"LOCATION_ID",
"dataType":"VARCHAR2",
"dataLength":20,
"nullable":"N"
}
},
"available":{
"type":"Number",
"required":false,
"length":22,
"oracle":{
"columnName":"AVAILABLE",
"dataType":"NUMBER",
"dataLength":22,
"nullable":"Y"
}
},
"total":{
"type":"Number",
"required":false,
"length":22,
"oracle":{
"columnName":"TOTAL",
"dataType":"NUMBER",
"dataLength":22,
"nullable":"Y"
}
}
}
}
`

Type mapping

See LoopBack types for details on LoopBack's data types.

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Discovery and auto-migration

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The Oracle connector supports _model discovery_ that enables you to create LoopBack models
based on an existing database schema using the unified database discovery API. For more information on discovery, see Discovering models from relational databases.

For an example of model discover, see example/app.js.

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The Oracle connector also supports _auto-migration_ that enables you to create a database schema
from LoopBack models using the LoopBack automigrate method.

For more information on auto-migration, see Creating a database schema from models for more information.

LoopBack Oracle connector creates the following schema objects for a given model:

* A table, for example, PRODUCT
* A sequence for the primary key, for example, PRODUCT_ID_SEQUENCE
* A trigger to generate the primary key from the sequnce, for example, PRODUCT_ID_TRIGGER

Destroying models may result in errors due to foreign key integrity. First delete any related models by calling delete on models with relationships.

Running tests

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