koa-postgresql-pool-connector

koa-postgresql-pool-connector

The MIT License (MIT)

koa-postgresql-pool-connector is a wrapper on top of koa-pg ready to use.

Table of Contents

Practical information
Files tree
Installation
API documentation
Example
Acknowledgement
Other project

Practical information

You must be familiar with :

• ES6 generator
• Koa framework
• ES promise

Files tree

    ./
    ├── examples                // Contain one working example.
    │   └── index.js
    ├── .gitignore
    ├── index.js                // Current npm module sources
    ├── LICENSE
    ├── package.json
    ├── README.md
    └── __tests__               // Jest Unit Tests
    │   └── index-test.js
    └── .travis.yml

Installation

    $ npm install koa-postgresql-pool-connector

API documentation

This is a simple code overview of how to use koa-postgresql-pool-connector. After you added the module to your nodeJs app, this.sqlQuery will be available from every koa generator scope functions.

this.sqlQuery

Param name	Description	Mandatory
databaseUrl	string which should contain the database connection info	YES
query	string which should contain the query to execute on PG db	YES
Return	promise which you could use as you want for callback	always present

    /**
     * module for db pool connection
     * @param databaseUrl key
     * @param query to execute by client
     * @return promise
     */

code simplification

const app = require( 'koa' )(),
    router = require( 'koa-joi-router' )(),
    dbCo = require( 'koa-postgresql-pool-connector' );

app.use( dbCo );
app.use( router.middleware() );

router.post('/example',function* (next){
const query = 'postegresql query';
    this.sqlQuery("urlDb",query)
    .then(function( respData ){
        //do your stuf after query execution
    })
});

Example

Following example could be found inside /examples directory.

Live test it by doing npm run devExample, which will start nodejs instance with koa/koaPostgres api with 3 working path. Don't forget to set a postgresSql Db on your local computer to make the example server work.

*current db url connection : postgres://postgres:postgres@localhost:5432/postgres

Example overview

• set every const we will need.

// const dbCo is our koa-postgresql-pool-connector
const koa = require( 'koa' ),
    dbCo = require( '../index.js' ),
    dbUrl = '',
    router = require( 'koa-joi-router' )(),
    bodyParser = require( 'koa-bodyparser' ),
    app = koa();

• add middlewares to Nodejs app.

// add our koa-postgresql-pool-connector module to nodeJs app as middleware.
app.use( dbCo );
// use a koa bodyparser to get form data as middleware.
app.use( bodyParser() );
// declare a koa joi router as middleware.
app.use( router.middleware() );

• create specifiques routes via koi-joi-router. We see that i passed callbacks to every routes

router
    .post( '/createFilmTable', function* ( next ) {
        'use strict';
// just call this.sqlQuery and you will get you function to request database with a query and a callback to execute at the end
        this.sqlQuery( 'postgres://postgres:postgres@localhost:5432/postgres',
            "CREATE TABLE films (" +
            "id serial NOT NULL,  CONSTRAINT films_pkey PRIMARY KEY (id)," +
            "title       varchar(40) NOT NULL," +
            "kind        varchar(10)," +
            ");"
        )
    } )
    .get( '/films/', function* ( next ) {
        'use strict';

        let that = this;

        yield this.sqlQuery( 'postgres://postgres:postgres@localhost:5432/postgres',
            "SELECT * FROM films;"
        ).then( function ( data ) {
            if ( data.name === "error" ) {
                that.status = 500;
                that.body = data;
            }
            if ( data.rowCount !== 0 ) {
                that.status = 200;
                that.body = { data: data.rows }
            }
            else {
                that.status = 204
            }
        } );
    } )
    .post( '/films/', function* ( next ) {
        'use strict';
        let data = this.request.body,
            that = this;

        if ( data.title && data.kind ) {
            yield this.sqlQuery( 'postgres://postgres:postgres@localhost:5432/postgres',
                          'INSERT INTO films (title,kind) VALUES (\'' + data.title + '\',\'' + data.kind + '\')' )
                      .then( function ( data ) {
                          console.log( arguments );
                          if ( data.name === "error" ) {
                              that.status = 500;
                              that.body = data;
                          }
                          if ( data && data.rowCount !== 0 ) {
                              that.status = 200;
                              that.body = { data: data.rows };
                          }
                          else {
                              that.status = 204;
                          }
                      } );
        }
        else {
            this.status = 400;
            this.body = { error: 'missing title or kind key with values' };
        }
    } );

• register start nodejs server on port 3000

app.listen( 3000 );

Acknowledgement

Thanks to @Companeo for let me post this module I developped for work under open source license. Thanks to @MathRobin for his help and introduction to Koa.

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