bookshop

Bookshop Sample - Attachments Plugin

This sample demonstrates how to use the cds-feature-attachments plugin in a CAP Java application. It extends the classic CAP bookshop sample to include file attachments for books.

What This Sample Demonstrates

• Integration of the latest attachments plugin with CAP Java
• Extending existing entities with attachment capabilities
• UI integration with Fiori elements applications
• Basic attachment operations (upload, download, delete)

Prerequisites

• Java 17 or higher
• Maven 3.6 or higher
• Node.js 18 or higher
• npm

Getting Started

1. Clone and navigate to the sample:

   cd samples/bookshop

2. Install dependencies:

   mvn clean compile

3. Run the application:

   mvn spring-boot:run

4. Access the application:

   • Browse Books: http://localhost:8080/browse/index.html
   • Admin Books: http://localhost:8080/admin-books/index.html

Using Attachments

Once the application is running:

1. Navigate to the Books app (browse or admin)
2. Select any book to open its details
3. Scroll down to find the "Attachments" section
4. Use the attachment controls to:
   • Upload files by clicking the upload button
   • View uploaded files in the attachment list
   • Download files by clicking on them
   • Delete files using the delete button

Implementation Details

Maven Configuration

The attachments plugin is added to srv/pom.xml:

<dependency>
    <groupId>com.sap.cds</groupId>
    <artifactId>cds-feature-attachments</artifactId>
</dependency>

The cds-maven-plugin includes the resolve goal to make CDS models from dependencies available:

<plugin>
    <groupId>com.sap.cds</groupId>
    <artifactId>cds-maven-plugin</artifactId>
    <executions>
        <execution>
            <id>cds.resolve</id>
            <goals>
                <goal>resolve</goal>
            </goals>
        </execution>
        <!-- other executions -->
    </executions>
</plugin>

CDS Model Extension

The srv/attachments.cds file extends the Books entity with attachments:

using { sap.capire.bookshop as my } from '../db/schema';
using { sap.attachments.Attachments } from 'com.sap.cds/cds-feature-attachments';

extend my.Books with {
  attachments: Composition of many Attachments;
}

UI Integration

The same file adds UI facets for both services to display attachments in the Fiori apps:

using { CatalogService as service } from '../app/services';
annotate service.Books with @(
  UI.Facets: [
    {
      $Type  : 'UI.ReferenceFacet',
      ID     : 'AttachmentsFacet',
      Label  : '{i18n>attachments}',
      Target : 'attachments/@UI.LineItem'
    }
  ]
);

Storage Configuration

This sample uses the default in-memory storage, which stores attachments directly in the H2 database. For production scenarios, consider using object store backends.

Advanced Configuration

For advanced topics like object store integration, malware scanning, and security configuration, see the main project documentation.

Troubleshooting

• Port conflicts: If port 8080 is in use, specify a different port: mvn spring-boot:run -Dspring-boot.run.arguments="--server.port=8081"
• Memory issues: Increase JVM heap size: export MAVEN_OPTS="-Xmx2g"
• File upload issues: Check browser developer console for error messages
• View loading issues: If your view doesn’t load, try clearing the cache and local storage for localhost (and the relevant port) in your browser settings or try a private/incognito tab.