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Configure SAP Build Application to Open Device Camera

Configure the logic flow in your application to enable your device to open your camera on demand, whenever the user clicks the Scan button.
You will learn
  • How to add logic to a button in your mobile application
  • How to connect user interface elements to actions in your mobile application
thecodesterDaniel WroblewskiMarch 5, 2023
Created by
September 20, 2021

Logic flows are used to capture events in an application, such as a page loading or a user tapping on a button, and to execute actions. To create a barcode scanning app, you need to configure a logic flow that tells your application to open the camera device once the user taps the Scan button. To do this, we’ll show you how to add the logic to the button, then how to take advantage of SAP Build Apps’s QR and Barcode component.

  • Step 1

    Open your app, and in the Composer, click the Scan button and then click Add Logic to BUTTON 1 (bottom right).

    Add logic to button
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  • Step 2

    In the logic panel, you can see the Event - Component Tap, which captures when a user taps on the button within the application. We now need to decide what this event triggers.

    1. Using the core logic components, scroll down to the Device – Scan QR / barcode component and drag and drop this into the logic editor. This is a preconfigured QR or barcode scanner component provided by SAP Build Apps, one of many available within your SAP Build Apps account.

      Add Scan QR logic to logic editor
    2. Click the existing Component Tap connection and manually draw a connection to the Device connector. This connector simply indicates the flow direction, which in this case is the button being tapped and then that triggering the camera device opening.

      Manually draw a connector between the elements
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  • Step 3

    To test that the QR/barcode scanner is working, you’ll add an Alert component to the application. This will simply show a pop-up alert once a barcode has been scanned, returning the barcode number to the screen.

    1. To do this, return to the core logic options, scroll to Alert, and drag and drop this alongside the Scan QR/barcode logic.

      Add an alert logic
    2. Add a connector between the top Scan QR/Barcode option and the Alert element, again indicating the flow direction.

      Add connector to the alert element

      There are 3 outputs for the scan element. Connect the top output to the alert logic.

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  • Step 4

    As the alert is currently set to display a static text response only, we want to add a dynamic binding here. This allows us to tell the app what information to provide instead, which in our case is the barcode being scanned.

    1. To do this, select the Alert element and using the properties panel, click Currently bound to: Static text, opening the binding options screen.

      Currently bound to element
    2. Click Output value of another node.

      Output value of another node

      Configure the binding to the following:

      • Select logic node – Scan QR/barcode
      • Select node output – Scan QR/barcode / QR barcode content
    3. Click Save.

      Edit binding and then click Save

    Which type of binding is used in this tutorial for the alert message?

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  • Step 5
    1. Click Save in the upper right, to save all changes to the application.

      Save application
    2. Using your device, open your draft application in the SAP Build Apps preview app and test the feature with a food item barcode.

      Open smart phone app

      Tapping the Scan button will now automatically open your device camera.

      Tap scan button

      And scanning a barcode will return the barcode number only, as no further information has been configured for the event yet.

    As an example:

    View results

    In the example, what is the barcode number of the scanned food item?

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