Book Image

Mastering PostGIS

By : Dominik Mikiewicz, Michal Mackiewicz , Tomasz Nycz
Book Image

Mastering PostGIS

By: Dominik Mikiewicz, Michal Mackiewicz , Tomasz Nycz

Overview of this book

PostGIS is open source extension onf PostgreSQL object-relational database system that allows GIS objects to be stored and allows querying for information and location services. The aim of this book is to help you master the functionalities offered by PostGIS- from data creation, analysis and output, to ETL and live edits. The book begins with an overview of the key concepts related to spatial database systems and how it applies to Spatial RMDS. You will learn to load different formats into your Postgres instance, investigate the spatial nature of your raster data, and finally export it using built-in functionalities or 3th party tools for backup or representational purposes. Through the course of this book, you will be presented with many examples on how to interact with the database using JavaScript and Node.js. Sample web-based applications interacting with backend PostGIS will also be presented throughout the book, so you can get comfortable with the modern ways of consuming and modifying your spatial data.
Table of Contents (9 chapters)

Implementing a simple CRUD application that demonstrates vector editing via web interfaces


Our final example in this chapter demonstrates some simple spatial CRUD functionality. CRUD stands for Create, Read, Update, Destroy, so to put it simply we'll edit some features on the map. We will do it using ol3.

WebGIS CRUD server in Node.js

In order to expose our crud API, we will need some storage for our features, so let's start with creating a table of the geometries first:

create table webgis.crud (id serial NOT NULL, geom geometry); 

Once this is ready, we will need a simple web server to handle our CRUD operations. Let's take care of that.

First, we need to put some packages in place:

npm install express --save
npm install body-parser --save
npm install pg --save

Once the appropriate packages are installed, let's create our server:

const pg = require("pg"); 
const express = require('express'); 
const app = express(); 

const bodyParser = require('body-parser'); 

// configure app to use bodyParser...