README
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.
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.