SAP HANA XS Advanced, Creating a Node.js Module

Creating a Node.js Module and implementing XSJS and XSODATA

🎓beginner ⏱15 min SAP HANA Beginner Odata Express Edition 0/6

Overview

🎓 beginner ⏱ 15 min. SAP HANABeginnerOdataExpress Edition

T Thomas Jung November 1, 2022

Created by September 5, 2016

Contributors

Prerequisites

This tutorial is designed for SAP HANA on premise and SAP HANA, express edition. It is not designed for SAP HANA Cloud.
Proficiency: beginner
Tutorials: SAP HANA XS Advanced, Creating an HDI Module

Steps

Open all Close all

Next Steps

Create a simple OData service

Time to Complete

15 Min.

Step 1 Create a Node.js module

—

Like the previous exercises, you will start by creating a new module. New->Node.js Module

Name the module core_xsjs and press Next.

Be sure to check the box Enable XSJS support. Then press Next. Then press Finish.

Once again the mta.yaml file has been extended to add the core_xsjs module.

This XSJS module will also need the UAA service for authentication. Additionally, it will need data from the database module and the HDI container behind it. Add those dependencies to the node module

Now you need to add the dependency from the web module to this new Node.js module and a destination route to it as well.

In the Requires section of the web module, add core_xsjs_api

If you are editing this manually, this should match the name of the value under Provides in the new node module

Add destinations in the field group and the following key-value pairs as the properties for the core_xsjs_api module:

Code

name: core-xsjs-backend
url: ~{url}
forwardAuthToken: true

The complete section for the web module should now look like this:

What is this configuration for?
The approuter is a module that serves as a single point of entry to a Multi-Target Application. In this case, the web module contains the call to this module in the package.json file. The approuter will use routes to determine the destination for a request coming from, for example, a web browser. The configuration you have just entered is naming the Node.js destination as core-xsjs-backend, URL is picking up the value from the provides URL, which is in turn taking it from the reserved environment variable, default-url.
Later at deploy, the destination routing builds a dependency and navigation ability between the two services without ever having to hard code the URLs or ports. They are assigned at deploy time and all references are automatically updated.

Save the yaml file and go into the code editor. Copy the definition of the node module in the validation below:

Step 2 Configure Routes

You can now add rules for redirecting certain requests to the web module into other modules in this project.

Open the file xs-app.json in the web module and fill in the routes with the following configuration

JSON
"routes": [{
  "source": "(.*)(.xsjs)",
  "destination": "core-xsjs-backend",
  "csrfProtection": false,
  "authenticationType": "xsuaa"
}, {
  "source": "(.*)(.xsodata)",
  "destination": "core-xsjs-backend",
  "authenticationType": "xsuaa"

}]

This is where you are configuring that any file request with the extension .xsjs or .xsodata should be rerouted internally to the Node.js destination that you defined in the mta.yaml file.

This is what the section should like:

Step 3 Enable authentication in your service

Step 4 Create an OData service

In the lib folder, create a sub-folder called xsodata.

Create a file named purchaseOrder.xsodata. In the latest versions of Web IDE, you can create both objects at the same time using New->File as follows:

Here you expose both the Header and Item tables from your HDI container as separate entities and build a navigation association between the two.

SQL
service {
    "PurchaseOrder.Header"
	  as "POHeader" navigates ("Items" as "POItem");

	"PurchaseOrder.Item"
	  as "POItem";

	association "Items" principal  "POHeader"("PURCHASEORDERID")
	multiplicity "1" dependent "POItem"("POHeader.PURCHASEORDERID") multiplicity "*";
}

You can ignore the warning from XSODataValidator this time

Step 5 Create an XSJS service

In the lib folder, create a sub-folder called xsjs and a file named hdb.xsjs.

Here is the source code for this file.

JavaScript
/*eslint no-console: 0, no-unused-vars: 0, no-shadow: 0, new-cap: 0*/
/*eslint-env node, es6 */
"use strict";

let conn = $.hdb.getConnection();
let query =
	`SELECT  "POHeader.PURCHASEORDERID" as "PurchaseOrderItemId",
             PRODUCT as "ProductID",
             GROSSAMOUNT as "Amount"
             FROM "PurchaseOrder.Item" `;
let rs = conn.executeQuery(query);

let body = "";
for(let item of rs){
   if(item.Amount >= 500){
	body += item.PurchaseOrderItemId + "\t" +
			item.ProductID + "\t" + item.Amount + "\n";
   }
}
$.response.setBody(body);
$.response.contentType = "application/vnd.ms-excel; charset=utf-16le";
$.response.headers.set("Content-Disposition",
		"attachment; filename=Excel.xls");
$.response.status = $.net.http.OK;