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Add Custom Logic to Your Service

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Add Custom Logic to Your Service

Add Custom Logic to Your Service

Add custom handlers with the SAP Cloud Application Programming Model for specific situations that are not covered by the generic service provider.

You will learn

  • How to add custom handlers in your service model to adapt to situations that are not covered by the generic service provider

Step 1: Add a new Java class
  1. In the srv module, go to src/main/java/my/bookshop and open the context menu.

  2. Choose New | Java Class.

    Add Java Class
  3. Enter OrdersService as the name and choose Next.

    Enter name for Java class
  4. Choose Finish.

    The file is created.

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Step 2: Add custom code
  1. Open the new file and replace the template with the following code:

    package my.bookshop;
    import java.util.ArrayList;
    import java.util.List;
    import org.slf4j.*;
    public class OrdersService {
      private static final Logger LOG = LoggerFactory.getLogger (OrdersService.class.getName());
      @BeforeRead (entity="Orders", serviceName="CatalogService")
      public BeforeReadResponse beforeReadOrders (ReadRequest req, ExtensionHelper h){
        LOG.error ("##### Orders - beforeReadOrders ########");
        return BeforeReadResponse.setSuccess().response();
      @AfterRead (entity = "Orders", serviceName="CatalogService")
      public ReadResponse afterReadOrders (ReadRequest req, ReadResponseAccessor res, ExtensionHelper h) {
        EntityData ed = res.getEntityData();
        EntityData ex = EntityData.getBuilder(ed).addElement("amount", 1000).buildEntityData("Orders");
        return ReadResponse.setSuccess().setData(ex).response();
      @AfterQuery (entity = "Orders", serviceName="CatalogService")
      public QueryResponse afterQueryOrders (QueryRequest req, QueryResponseAccessor res, ExtensionHelper h) {
        List<EntityData> dataList = res.getEntityDataList(); //original list
        List<EntityData> modifiedList = new ArrayList<EntityData>(dataList.size()); //modified list
        for(EntityData ed : dataList){
    		  EntityData ex = EntityData.getBuilder(ed).addElement("amount", 1000).buildEntityData("Orders");
        return QueryResponse.setSuccess().setData(modifiedList).response();
  2. Save your changes.

    In this sample code, we set a value of 1000 for the property amount of each returned entity in reading operations.

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Step 3: Run the application
  1. Right-click the srv module and choose Run | Java Application.

  2. Go to the Run Console and click on the URL.

  3. Add CatalogService/Orders to the URL.

    Look for amount and enter the value in the text area below.


Next Steps

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