PostgreSQL components for Node.js

This module is a part of the Pip.Services polyglot microservices toolkit. It provides a set of components to implement PostgreSQL persistence.

The module contains the following packages:

• Build - Factory to create PostreSQL persistence components.
• Connect - Connection component to configure PostgreSQL connection to database.
• Persistence - abstract persistence components to perform basic CRUD operations.

Quick links:

• Configuration
• API Reference
• Change Log
• Get Help
• Contribute

Use

Install the NPM package as

npm install pip-services3-postgres-node --save

As an example, lets create persistence for the following data object.

import { IIdentifiable } from 'pip-services3-commons-node';

export class MyObject implements IIdentifiable {
  public id: string;
  public key: string;
  public value: number;
}

The persistence component shall implement the following interface with a basic set of CRUD operations.

export interface IMyPersistence {
  getPageByFilter(correlationId: string, filter: FilterParams, paging: PagingParams,
    callback: (err: any, page: DataPage<MyObject>) => void): void;
    
  getOneById(correlationId: string, id: string, callback: (err: any, item: MyObject) => void): void;
    
  getOneByKey(correlationId: string, key: string, callback: (err: any, item: MyObject) => void): void;
    
  create(correlationId: string, item: MyObject, callback?: (err: any, item: MyObject) => void): void;
    
  update(correlationId: string, item: MyObject, callback?: (err: any, item: MyObject) => void): void;
    
  deleteById(correlationId: string, id: string, callback?: (err: any, item: MyObject) => void): void;
}

To implement postgresql persistence component you shall inherit IdentifiablePostgresPersistence. Most CRUD operations will come from the base class. You only need to override getPageByFilter method with a custom filter function. And implement a getOneByKey custom persistence method that doesn't exist in the base class.

import { IdentifiablePostgresPersistence } from 'pip-services3-postgres-node';

export class MyPostgresPersistence extends IdentifablePostgresPersistence {
  public constructor() {
    super("myobjects");
    this.autoCreateObject("CREATE TABLE myobjects (id VARCHAR(32) PRIMARY KEY, key VARCHAR(50), value VARCHAR(255)");
    this.ensureIndex("myobjects_key", { key: 1 }, { unique: true });
  }

  private composeFilter(filter: FilterParams): any {
    filter = filter || new FilterParams();
    
    let criteria = [];

    let id = filter.getAsNullableString('id');
    if (id != null)
        criteria.push("id='" + id + "'");

    let tempIds = filter.getAsNullableString("ids");
    if (tempIds != null) {
        let ids = tempIds.split(",");
        filters.push("id IN ('" + ids.join("','") + "')");
    }

    let key = filter.getAsNullableString("key");
    if (key != null)
        criteria.push("key='" + key + "'");

    return criteria.length > 0 ? criteria.join(" AND ") : null;
  }
  
  public getPageByFilter(correlationId: string, filter: FilterParams, paging: PagingParams,
    callback: (err: any, page: DataPage<MyObject>) => void): void {
    super.getPageByFilter(correlationId, this.composeFilter(filter), paging, "id", null, callback);
  }  
  
  public getOneByKey(correlationId: string, key: string,
    callback: (err: any, item: MyObject) => void): void {
    
    let query = "SELECT * FROM " + this.quoteIdentifier(this._tableName) + " WHERE \"key\"=$1";
    let params = [ key ];

    this._client.query(query, params, (err, result) => {
      err = err || null;

      let item = result && result.rows ? result.rows[0] || null : null; 

      if (item == null)
        this._logger.trace(correlationId, "Nothing found from %s with key = %s", this._tableName, key);
      else
        this._logger.trace(correlationId, "Retrieved from %s with key = %s", this._tableName, key);

      item = this.convertToPublic(item);
      callback(err, item);
    });
  }

}

Alternatively you can store data in non-relational format using IdentificableJsonPostgresPersistence. It stores data in tables with two columns - id with unique object id and data with object data serialized as JSON. To access data fields you shall use data->'field' expression or data->>'field' expression for string values.

import { IdentifiableJsonPostgresPersistence } from 'pip-services3-postgres-node';

export class MyPostgresPersistence extends IdentifableJsonPostgresPersistence {
  public constructor() {
    super("myobjects");
    this.ensureTable("VARCHAR(32)", "JSONB");
    this.ensureIndex("myobjects_key", { "data->>'key'": 1 }, { unique: true });
  }

  private composeFilter(filter: FilterParams): any {
    filter = filter || new FilterParams();
    
    let criteria = [];

    let id = filter.getAsNullableString('id');
    if (id != null)
        criteria.push("data->>'id'='" + id + "'");

    let tempIds = filter.getAsNullableString("ids");
    if (tempIds != null) {
        let ids = tempIds.split(",");
        filters.push("data->>'id' IN ('" + ids.join("','") + "')");
    }

    let key = filter.getAsNullableString("key");
    if (key != null)
        criteria.push("data->>'key'='" + key + "'");

    return criteria.length > 0 ? criteria.join(" AND ") : null;
  }
  
  public getPageByFilter(correlationId: string, filter: FilterParams, paging: PagingParams,
    callback: (err: any, page: DataPage<MyObject>) => void): void {
    super.getPageByFilter(correlationId, this.composeFilter(filter), paging, "id", null, callback);
  }  
  
  public getOneByKey(correlationId: string, key: string,
    callback: (err: any, item: MyObject) => void): void {
    
    let query = "SELECT * FROM " + this.quoteIdentifier(this._tableName) + " WHERE data->>'key'=$1";
    let params = [ key ];

    this._client.query(query, params, (err, result) => {
      err = err || null;

      let item = result && result.rows ? result.rows[0] || null : null; 

      if (item == null)
        this._logger.trace(correlationId, "Nothing found from %s with key = %s", this._tableName, key);
      else
        this._logger.trace(correlationId, "Retrieved from %s with key = %s", this._tableName, key);

      item = this.convertToPublic(item);
      callback(err, item);
    });
  }

}

Configuration for your microservice that includes postgresql persistence may look the following way.

...
{{#if POSTGRES_ENABLED}}
- descriptor: pip-services:connection:postgres:con1:1.0
  connection:
    uri: {{{POSTGRES_SERVICE_URI}}}
    host: {{{POSTGRES_SERVICE_HOST}}}{{#unless POSTGRES_SERVICE_HOST}}localhost{{/unless}}
    port: {{POSTGRES_SERVICE_PORT}}{{#unless POSTGRES_SERVICE_PORT}}5432{{/unless}}
    database: {{POSTGRES_DB}}{{#unless POSTGRES_DB}}app{{/unless}}
  credential:
    username: {{POSTGRES_USER}}
    password: {{POSTGRES_PASS}}
    
- descriptor: myservice:persistence:postgres:default:1.0
  dependencies:
    connection: pip-services:connection:postgres:con1:1.0
  table: {{POSTGRES_TABLE}}{{#unless POSTGRES_TABLE}}myobjects{{/unless}}
{{/if}}
...

Develop

For development you shall install the following prerequisites:

• Node.js 8+
• Visual Studio Code or another IDE of your choice
• Docker
• Typescript

Install dependencies:

npm install

Compile the code:

tsc

Run automated tests:

npm test

Generate API documentation:

./docgen.ps1

Before committing changes run dockerized build and test as:

./build.ps1
./test.ps1
./clear.ps1

Contacts

The library is created and maintained by Sergey Seroukhov.

The documentation is written by Mark Makarychev.