Exercise: Querying SAP APIs in a TypeScript NestJS application

In this exercise, you will learn how to query the Business Partner API of SAP S/4HANA Cloud. We will use the Mock Server instead of the actual SAP S/4HANA Cloud.

1. Clone the SAP Cloud SDK Samples repository and checkout the branch tsnestjs_v1.0_query in SAP Business Application Studio

   1. Open SAP Business Application Studio.

   2. Run the following commands in the terminal

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      cd ~/projects
      git clone https://github.com/SAP-samples/cloud-sdk-learning-journey.git
      cd cloud-sdk-learning-journey
      git checkout tsnestjs_v1.0_query

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2. Build and run the project

   1. Open the cloud-sdk-learning-journey folder in the workspace

      

   2. Run the application by executing the following commands in the terminal

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      cd cloudsdk_bp_ts
      npm i -g @nestjs/cli
      npm i
      npm run start:dev

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3. Query the Business Partner API of SAP S/4HANA Cloud

   1. Open the requests.http file

   2. Click on Send Request in the requests.http file to submit the GET request for business partners

   3. Verify that the list of business partners are returned from the Mock Server. Note: If the Mock Server is not running, make sure to run the Mock Server on port 8081 by following the prerequisites at the top

   4. Optional: Open .env file in the root folder. Replace the URL property with https://sandbox.api.sap.com/s4hanacloud to retrieve business partners from SAP API Business Hub. Note that you also have to provide the APIKEY

      

4. Optional: Review code in the following source files

   1. Note

      Check out the SAP Cloud SDK documentation on Executing an OData GET request using SAP Cloud SDK for JavaScript. https://sap.github.io/cloud-sdk/docs/js/tutorials/getting-started/execute-an-odata-request

      Code walk-through

      File name	Comments on code changes
      business-partner.controller.ts	Code logic is as follows... Annotate the method getBusinessPartners with @Get() to handle the GET method Call the getAllBusinessPartners method of the BusinessPartnerService instance asynchronously
      business-partner.service.ts	Code logic is as follows... Annotate the class BusinessPartnerService with @Injectable() to enable dependency injection Call the getAll method to retrieve the business partners Use the SAP Cloud SDK fluent API method chaining to provide additional parameters Return the list of business partners
      requests.http	Provides various HTTP requests that can be submitted to query the Business Partner API
      commands.txt	Provides various commands that can be run on the terminal

5. Optional: Manually create the project

   1. Create a new project by running the following command in the terminal and install dependencies. Select npm when prompted for the package manager

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      cd ~/projects
      npm i -g @nestjs/cli
      nest new cloudsdk_bp_ts
      cd cloudsdk_bp_ts
      npm install -D @sap-cloud-sdk/generator
      npm install @nestjs/config @sap-cloud-sdk/http-client @sap-cloud-sdk/resilience @sap-cloud-sdk/odata-v2

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   2. Open the cloudsdk_bp_ts folder in the workspace. Edit the main.ts file to listen on port 8080

      

      

   3. Create a new controller and service by executing the following command

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      cd ~/projects/cloudsdk_bp_ts
      nest g controller business-partner
      nest g service business-partner

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   4. Create a folder named service-specifications at the root of the project

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      mkdir service-specifications

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   5. Browse to the SAP API Business Hub in a separate tab, then login.

   6. Click on API Specification button and click on the download EDMX button. This will download the API_BUSINESS_PARTNER.edmx file

      

   7. Copy the API_BUSINESS_PARTNER.edmx file into the service-specifications folder

      

   8. Create a file named options-per-service.json in the service-specifications folder. Copy contents from here...

   9. Generate the BusinessPartner service by running the following command

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      npx generate-odata-client --input service-specifications --outputDir services --optionsPerService service-specifications/options-per-service.json

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   10. Create or update the following files in the table below

       File name	Type	Contents
       business-partner.controller.ts Path: ~/projects/cloudsdk_bp_ts/src/business-partner	Modified	Copy contents from here...
       business-partner.service.ts Path: ~/projects/cloudsdk_bp_ts/src/business-partner	Modified	Copy contents from here...
       app.module.ts Path: ~/projects/cloudsdk_bp_ts/src	Modified	Copy contents from here...
       .env Path: ~/projects/cloudsdk_bp_ts	New	Copy the following contents APIKEY=YOUR_API_KEY URL=http://localhost:8081/
       requests.http Path: ~/projects/cloudsdk_bp_ts	New	Copy contents from here...