Port of Antwerp from the Opendata challenge perspective – part 3

As stated before HANA does support this format yet with the proper ST_GEOMETRY data type constructor or constructor. So we will need to convert this field to a “Well-Known Text” format.

I found a “Node.js” package to do this (only one), so I decided to build a little program to convert the field from the local CSV file.

First you will need to install Node.js from their website: https://nodejs.org/en/download/

Once installed you can open command line prompt and run the following command:

node --version

This will return the currently installed and make sure it’s properly installed.

Now, run the following commands:
npm install fast-csv
npm install fs
npm install terraformer
npm install terraformer-wkt-parser

This will install the relevant packages to run the package.

You can now create a new file named ‘convert-geojson-to-wkt-csv.js‘ and add the following code:
var csv = require('fast-csv');
var fs = require('fs');
var Terraformer = require('terraformer');
var WKT = require('terraformer-wkt-parser');

var writeOptions = {
headers : true,
quoteHeaders : true,
quoteColumns : true,
rowDelimiter :'\n',
delimiter : ';'
};

var csvWriteStream = csv
.format(writeOptions);

var writableStream = fs.createWriteStream("C:/temp/grondwaterstroming-out.csv")
.on("finish", function(){
console.log("All done");
});

csvWriteStream.pipe(writableStream);

var readOptions = {
objectMode : true,
headers : true,
delimiter : ';',
quote : '"',
escape : '"'
};

var csvReadStream = fs.createReadStream("C:/temp/grondwaterstroming.csv");

var csvStream = csv
 .parse(readOptions)
 .on("data", function(data){
data.geometry = WKT.convert(JSON.parse(data.geometry));
csvWriteStream.write(data);
 })
 .on("end", function(){
csvWriteStream.end();
 });

csvReadStream.pipe(csvStream);

The program will read the ‘C:/temp/grondwaterstroming.csv‘ file and out the result in ‘C:/temp/grondwaterstroming-out.csv‘ where the geoJSON field will be converted in a WKT format.

You can now run the following command:
node convert-geojson-to-wkt-csv.js

And you can now check the output file: ‘C:/temp/grondwaterstroming-out.csv‘

Let’s now import that files in HANA Studio like we did in the last blog, but this set the geometry field to ST_GEOMETRY instead of BLOB.