Create a Data Model and Expose It as a Service

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Create a Data Model and Expose It as a Service

Details

Create a Data Model and Expose It as a Service

Requires Customer/Partner License

Raz Korn

November 15, 2021

Created by

November 14, 2021

Beginner

15 min.

Create a capital expenditures data model and expose it via a service, using the low-code capabilities of SAP Business Application Studio.

You will learn

How to create a project from scratch from the Application Development Lobby
How to create a data model for your application
How to expose the data using a service so that you’ll be able to use it in your apps
How to add sample data
How to preview the service definition
How to view the data before creating apps

Prerequisites

You have access to your Application Development Lobby.

Step 1: Create a project

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.
Within the Application Development Lobby, click Create and select Business Application.
Provide a Project Name, e.g. CapitalExpenditures, and click Create.
Wait for the homepage of SAP Business Application Studio for low-code development to load.

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).

Done

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Step 2: Model your data: Entities

From the homepage, click the + of the Data Model tile to add a data model to your project.
Provide an Entity Name for the entity e.g. Capex, and choose Create.
Click the + to add a property to the Capex entity.

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)

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.

Access the Home tab.
Click the + of the Data Model tile to add a data model to your project.
Provide an Entity Name for the entity e.g. Contractors.
Change the Property Name of the ID property to contractor, and its Property Type to Integer.

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.

Done

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Step 3: Model your data: Relationship between entities

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

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)

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

Done

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Step 4: Expose your data

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

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.

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.

Select the Capex service (Which gets highlighted with a blue rectangle indication), and check the Draft Editing property.
You can re-arrange the entities on the canvas manually or by clicking the Auto Layout icon to improve the service visualization.
Access the Home tab. You can see that both the services are added to the Service tile.

When the app is running, how does it access the data? Through a service Accessing the database directly using SQL commands Generates a batch file that communicates with the data model A deep learning algorithm that acts as a bridge between the user and the database.

Step 5: Preview your data

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.

Choose the Preview option from the homepage.
A new tab appears with the links which allow you to test the service definition, access data exposed by the service, and more.
Choose the $metadata to view the service’s XML.
Choose the browser’s Back button, and select the Capex or the Contractors links to view the data from the respective service.

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

Done

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Step 6: Add sample data and preview it

View Full Instructions

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.

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

Add the sample data, e.g.

CONTRACTOR;NAME
1;SAP
2;Backer Berlin
3;Pear Computing Services
4;C.R.T.U.

Repeat steps 1 - 3 for the Capex data model. Add the following sample data:

ID;DESCRIPTION;TOTAL_COST;CONTRACTOR_CONTRACTOR
7bef2fdf-9b31-4e24-994a-81bb2c28c828;Solar panel connectors;384;4
3e6ad791-d531-4547-b4ad-f546a3dcfe14;Laptop maintenance;12645;3
7e7e667e-f52b-4aaa-8d8c-823d1d69f5f3;Bicycles;1723;2

Access the Home tab. You can see that the sample data is added to the Sample Data tile.
Go back to the browser tab with the links to the services, 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.