SAP CAP App

You are a SAP CAP (Cloud Application Programming Model) developer. The user wants to build a full-stack application using SAP CAP with Node.js, including data models, services, and UI.

What to check first

• Run cds --version to verify CAP CLI is installed; if not, install with npm install -g @sap/cds-dk
• Check Node.js version with node --version (CAP requires Node.js 14 or later)
• Verify package.json exists in your project root with CAP dependencies

Steps

1. Initialize a new CAP project with cds init my-app && cd my-app to scaffold the project structure with db/, srv/, and app/ directories
2. Define your data model in db/schema.cds using CDS syntax with entities, elements, and associations
3. Run cds build to compile your schema and generate database artifacts
4. Create a service in srv/cat-service.cds that exposes entities with service keyword and @odata annotations
5. Implement service logic in srv/cat-service.js using handler functions like on('READ', ...) and on('CREATE', ...)
6. Add Fiori Elements UI by placing manifest files in app/ directory or use cds add fiori to scaffold automatically
7. Test locally with cds watch which starts the dev server, rebuilds on file changes, and provides the CAP Fiori preview
8. Deploy using cds deploy --to hana for HANA or cds deploy --to sqlite for local SQLite database

Code

// db/schema.cds - Define your data model
namespace com.example.bookstore;

entity Books {
  key ID : UUID;
  title : String;
  author : String;
  ISBN : String;
  price : Decimal(9,2);
  stock : Integer;
  reviews : array of {
    rating : Integer;
    comment : String;
  };
  author_ID : UUID;
}

entity Authors {
  key ID : UUID;
  name : String;
  email : String;
  books : array of Books on books.author_ID = ID;
}

// srv/cat-service.cds - Expose entities via OData service
using { com.example.bookstore } from '../db/schema';

service BookService {
  entity Books as projection on bookstore.Books;
  entity Authors as projection on bookstore.Authors;
  
  type BookReport {
    title : String;
    totalStock : Integer;
  }
  
  function getBooksByAuthor(authorID : UUID) returns array of Books;
}

// srv/cat-service.js - Implement business logic
const cds = require('@sap/cds');

module.exports = cds.service.impl(async (srv) => {
  const db = await cds.connect.to('db');
  const {

Note: this example was truncated in the source. See the GitHub repo for the latest full version.

Common Pitfalls

• Treating this skill as a one-shot solution — most workflows need iteration and verification
• Skipping the verification steps — you don't know it worked until you measure
• Applying this skill without understanding the underlying problem — read the related docs first

When NOT to Use This Skill

• When a simpler manual approach would take less than 10 minutes
• On critical production systems without testing in staging first
• When you don't have permission or authorization to make these changes

How to Verify It Worked

• Run the verification steps documented above
• Compare the output against your expected baseline
• Check logs for any warnings or errors — silent failures are the worst kind

Production Considerations

• Test in staging before deploying to production
• Have a rollback plan — every change should be reversible
• Monitor the affected systems for at least 24 hours after the change