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    loopback-connector-oracle

    4.5.2 • Public • Published

    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.

    For more information, see the LoopBack documentation.

    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:

    $ 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" %}

    "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.

    Easy Connect

    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.

    Property Type Default Description
    host or hostname String localhost Host name or IP address of the Oracle database server
    port Number 1521 Port number of the Oracle database server
    username or user String   User name to connect to the Oracle database server
    password String   Password to connect to the Oracle database server
    database String XE Oracle database listener name

    For example:

    {% include code-caption.html content="/server/datasources.json" %}

    {
      "demoDB": {
        "connector": "oracle",
        "host": "oracle-demo.strongloop.com",
        "port": 1521,
        "database": "XE",
        "username": "demo",
        "password": "L00pBack"
      }
    }

    Local and directory naming

    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=<directory containing .ora files>
    

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

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

    Connection pooling options

    Property name Description Default value
    minConn Minimum number of connections in the connection pool 1
    maxConn Maxmimum number of connections in the connection pool 10
    incrConn

    Incremental number of connections for the connection pool.

    1
    timeout Time-out period in seconds for a connection in the connection pool. The Oracle connector will terminate connections in this connection pool that are idle longer than the time-out period. 10

    For example,

    {% include code-caption.html content="/server/datasources.json" %}

    {
      "demoDB": {
        "connector": "oracle",
        "minConn":1,
        "maxConn":5,
        "incrConn":1,
        "timeout": 10,
        ...
      }
    }

    Connection troubleshooting

    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" %}

    {
        "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.

    JSON to Oracle Types

    LoopBack Type Oracle Type
    String
    JSON
    Text
    default
    VARCHAR2
    Default length is 1024
    Number NUMBER
    Date DATE
    Timestamp TIMESTAMP(3)
    Boolean CHAR(1)

    Oracle Types to JSON

    Oracle Type LoopBack Type
    CHAR(1) Boolean
    CHAR(n)
    VARCHAR
    VARCHAR2,
    LONG VARCHAR
    NCHAR
    NVARCHAR2
    String
    LONG, BLOB, CLOB, NCLOB Node.js Buffer object
    NUMBER
    INTEGER
    DECIMAL
    DOUBLE
    FLOAT
    BIGINT
    SMALLINT
    REAL
    NUMERIC
    BINARY_FLOAT
    BINARY_DOUBLE
    UROWID
    ROWID
    Number
    DATE
    TIMESTAMP
    Date

    Discovery and auto-migration

    Model discovery

    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.

    Auto-migratiion

    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

    Own instance

    If you have a local or remote Oracle instance and would like to use that to run the test suite, use the following command:

    • Linux
    ORACLE_HOST=<HOST> ORACLE_PORT=<PORT> ORACLE_USER=<USER> ORACLE_PASSWORD=<PASSWORD> ORACLE_DATABASE=<DATABASE> npm test
    • Windows
    SET ORACLE_HOST=<HOST>
    SET ORACLE_PORT=<PORT>
    SET ORACLE_USER=<USER>
    SET ORACLE_PASSWORD=<PASSWORD>
    SET ORACLE_DATABASE=<DATABASE>
    npm test

    Docker

    If you do not have a local Oracle instance, you can also run the test suite with very minimal requirements.

    • Assuming you have Docker installed, run the following script which would spawn an Oracle instance on your local machine:
    source setup.sh <HOST> <PORT>

    where <HOST>, <PORT>, <USER>, and PASSWORD are optional parameters. The default values are localhost, 1521, admin, and 0raclep4ss respectively. The DATABASE setting is always XE.

    • Run the test:
    npm test

    Install

    npm i loopback-connector-oracle

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    Version

    4.5.2

    License

    MIT

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