Create a Data Model and Expose It as a Service

1. Projects are created from the Application Development Lobby. You can access the Lobby using its bookmark (if you saved it) or from the SAP BTP cockpit: Select the subaccount you created using the Set Up SAP Business Application Studio for Low-Code Development tutorial, expand Services, click Instances and Subscriptions, and choose SAP AppGyver.

2. Within the Application Development Lobby, click Create and select Business Application.

   

3. Provide a Project Name, e.g. CapitalExpenditures, and click Create.

   

4. Wait for the homepage of SAP Business Application Studio for low-code development to load.

   Wait for the “We have finished installing all tools and templates for you, enjoy your work!” notification.

   Loading SAP Business Application Studio for low-code development may take some time, especially if it’s the first time in a day.

   

   Close the notification icon at the bottom of the screen (optional).

1. From the homepage, click the + of the Data Model tile to add a data model to your project.

   

2. Provide an Entity Name for the entity e.g. Capex, and choose Create.

   

3. Click the + to add a property to the Capex entity.

   

4. Select the following:

   Step	Parameter	Value
   A	Property Name	description
   B	Property Type	String (default)
   C	Key Property	Leave unchecked (default)
   D	Null Value	Yes (default)
   E	Many	Leave unchecked (default)
   F	Other Facets (Max Length)	Leave empty (default)

   

5. Add the following property (click +), and choose Create.

   Step	Parameter	Value
   A	Property Name	total_cost
   B	Property Type	Integer
   C	Key Property	Leave unchecked (default)
   D	Max Length	Leave empty (default)
   E	Null Value	Yes (default)
   F	Many	Leave unchecked (default)

   

   The Capex entity appears in the Data Model Editor tab with a default ID property.

   To edit an entity, click the entity’s header and choose the Edit Entity icon.

   

6. Access the Home tab.

   

7. Click the + of the Data Model tile to add a data model to your project.

   

8. Provide an Entity Name for the entity e.g. Contractors.

   

9. Change the Property Name of the ID property to contractor, and its Property Type to Integer.

   

10. Add the following property to the Contractors entity, and choose Create.

    Step	Parameter	Value
    A	Property Name	name
    B	Property Type	String (default)
    C	Key Property	Leave unchecked (default)
    D	Null Value	Yes (default)
    E	Many	Leave unchecked (default)
    F	Other Facets (Max Length)	Leave empty (default)

    

    The Contractors entity appears in the Data Model Editor.

1. Select the Capex entity, choose the Add Relationship icon, and select the Contractors entity to add a relationship to the Contractors entity.

   
   

2. Select the following, and choose Create.

   Step	Parameter	Value
   A	Relationship	Association (default)
   B	Relationship Type	To-One (default)
   C	Property Name	contractor
   D	Target Entity Type	CapitaExpenditures.Contractors (default)
   E	Backlink Property	Leave empty (default)

   

3. You can re-arrange the entities on the canvas manually or by clicking the Auto Layout icon to improve the data model visualization.

   

1. Access the Home tab.

   

2. Click the + of the Service tile to add a service through which data from the data model can be accessed.

   

3. Define the following for your new service, and choose Create.

   Step	Parameter	Value
   A	Name	Capex
   B	Namespace	CapitalExpendituresService (default)
   C	Type	CapitalExpenditures.Capex
   D	<all properties>	Leave checked (default)
   E	ID	Leave checked (default)
   F	description	Leave checked (default)
   G	total_cost	Leave checked (default)
   H	contractor	Leave checked (default)

   

   The Capex service appears in the Service Editor tab.

4. Access the Home tab, and define the following new service.

   Step	Parameter	Value
   A	Name	Contractors
   B	Namespace	CapitalExpendituresService (default)
   C	Type	CapitalExpenditures.Contracotrs
   D	<all properties>	Leave checked (default)
   E	contractor	Leave checked (default)
   F	name	Leave checked (default)

   

   The Contractors service is added to the Service Editor, with association to the Capex service.

   

5. Select the Capex service (Which gets highlighted with a blue rectangle indication), and check the Draft Editing property.

   A draft is an interim version of a business entity that has not yet been explicitly saved as an active version. This allows users to be e.g. interrupted, and continue later on. For more information visit SAP Fiori Design Guidelines - Draft Handling.

   

6. You can re-arrange the entities on the canvas manually or by clicking the Auto Layout icon to improve the service visualization.

   

7. Access the Home tab. You can see that both the services are added to the Service tile.

   

It is a common practice in software development to test run any change to an app as soon as possible. Prior to having the services defined, you were not able to test the app. Since now you have defined the services, you can test them.

1. Choose the Preview option from the homepage, and select either With Sample Data or With Live Data option.

   

2. The project preview page appears in a new tab with the links which allow you to test the service definition, access data exposed by the service, and more.

   

3. Choose the metadata to view the service’s XML.

   

4. Select the Capex or the Contractors view as code to view the data from the respective service.

   

   Here, the value appears as an empty list since the data model is empty.

To test that the service works well, i.e. returns data when it is available in the data model, let’s add sample data to your project. Sample data is a powerful tool as it allows you to (1) develop an app with no connectivity to a data source; (2) Debug your app.

1. Go back to the browser tab with SAP Business Application Studio for low-code development, and click the + of the Sample Data tile.

   

2. Choose Create, select Contractors, and choose Create.

   

3. In the sample data editor add 4 rows.

   

4. Update the sample data as follows:

   

5. Access the Home tab, and click the + of the Sample Data tile.

   

6. Choose Create, select Capex, and choose Create.

   

7. In the sample data editor add 3 rows, and update the DESCRIPTION and CONTRACTOR columns as follows:

   

8. Access the Home tab. You can see that the sample data is added to the Sample Data tile.

   

9. Go back to the project preview browser tab, and click either the link of the Contractors service or the link of the Capex service. You can view the sample data you have added.