See also:

See also:

The LoopBack PostgreSQL connector enables LoopBack applications to connect to PostgreSQL databases.

Installation

shell
$ npm install loopback-connector-postgresql --save

This will install the module from npm and add it as a dependency to the application's package.json file.

Creating a data source

Use the Data source generator to add a PostgreSQL data source to your application. 

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

/server/datasources.json
"mydb": {
    "name": "mydb",
    "connector": "postgresql"
}

Edit datasources.json to add other properties that enable you to connect the data source to a PostgreSQL database.

Properties

PropertyTypeDescription
connectorString

Connector name, either "loopback-connector-postgresql" or "postgresql"

databaseStringDatabase name
debugBooleanIf true, turn on verbose mode to debug database queries and lifecycle.
hostStringDatabase host name
passwordStringPassword to connect to database
portNumberDatabase TCP port
urlStringUse instead of the hostportuserpassword, and database properties.  For example: 'postgres://test:mypassword@localhost:5432/dev'.
usernameStringUsername to connect to database
Icon

By default, the 'public' schema is used for all tables.

Defining models

The model definition consists of the following properties.

PropertyDefaultDescription
nameCamel-case of the database table nameName of the model.
optionsN/AModel level operations and mapping to PostgreSQL schema/table
propertiesN/AProperty definitions, including mapping to PostgreSQL column

For example:

/common/models/model.json
{"name": "Inventory", 
   "options": {
      "idInjection": false,
      "postgresql": {
        "schema": "strongloop",
        "table": "inventory"
      }
   }, 
   "properties": {
      "id": {
        "type": "String",
        "required": false,
        "length": 64,
        "precision": null,
        "scale": null,
        "postgresql": {
          "columnName": "id",
          "dataType": "character varying",
          "dataLength": 64,
          "dataPrecision": null,
          "dataScale": null,
          "nullable": "NO"
        }
      },
      "productId": {
        "type": "String",
        "required": false,
        "length": 20,
        "precision": null,
        "scale": null,
        "id": 1,
        "postgresql": {
          "columnName": "product_id",
          "dataType": "character varying",
          "dataLength": 20,
          "dataPrecision": null,
          "dataScale": null,
          "nullable": "YES"
        }
      },
      "locationId": {
        "type": "String",
        "required": false,
        "length": 20,
        "precision": null,
        "scale": null,
        "id": 1,
        "postgresql": {
          "columnName": "location_id",
          "dataType": "character varying",
          "dataLength": 20,
          "dataPrecision": null,
          "dataScale": null,
          "nullable": "YES"
        }
      },
      "available": {
        "type": "Number",
        "required": false,
        "length": null,
        "precision": 32,
        "scale": 0,
        "postgresql": {
          "columnName": "available",
          "dataType": "integer",
          "dataLength": null,
          "dataPrecision": 32,
          "dataScale": 0,
          "nullable": "YES"
        }
      },
      "total": {
        "type": "Number",
        "required": false,
        "length": null,
        "precision": 32,
        "scale": 0,
        "postgresql": {
          "columnName": "total",
          "dataType": "integer",
          "dataLength": null,
          "dataPrecision": 32,
          "dataScale": 0,
          "nullable": "YES"
        }
      }
    }}

Destroying models

If you destroy models,  you may get errors due to foreign key integrity.  Make sure to delete any related models first before calling delete() on models that have relationships.

Auto-migrate and auto-update

REVIEW COMMENT from Raymond via Rand

Removed temporarily. Is any of this still true?

The PostgreSQL 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.

After making changes to your model properties, you must call Model.automigrate() or Model.autoupdate().  Call Model.automigrate() only on new models since it will drop existing tables.  These methods will

  • Define a primary key for the properties whose id property is true (or a positive number).
  • Create a column with ‘SERIAL’ type if the generated property of the id property is true.

See Creating a database schema from models for more information.

Type mapping

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

LoopBack to PostgreSQL types

LoopBack TypePostgreSQL Type
String
JSON
Text
Default

VARCHAR2

Default length is 1024

NumberINTEGER
DateTIMESTAMP WITH TIME ZONE
BooleanBOOLEAN

PostgreSQL types to LoopBack

PostgreSQL TypeLoopBack Type
BOOLEANBoolean

VARCHAR
CHARACTER VARYING
CHARACTER
CHAR
TEXT

String
BYTEANode.js Buffer object
SMALLINT
INTEGER
BIGINT
DECIMAL
NUMERIC
REAL
DOUBLE
SERIAL
BIGSERIAL
Number
DATE
TIMESTAMP
TIME 
Date
POINTGeoPoint

Discovery methods

LoopBack provides a unified API to create models based on schema and tables in relational databases. The same discovery API is available when using connectors for Oracle, MySQL, PostgreSQL, and SQL Server.  For more information, see Database discovery API.