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Define a Validation Rule in an MDK App

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Define a Validation Rule in an MDK App
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Define a Validation Rule in an MDK App

October 29, 2020
Created by
April 23, 2019
Write a JavaScript logic to validate an email address format in an MDK app.

You will learn

  • How to write a rule to validate an UI field


MDK
Step 1: Create a validation message

When allowing end-users to make updates to data, it is important to add validation rules to verify that they are entering valid information.
If the Update action fails due to the validation rule, the application will display a validation failure message to the end-user. You can customize this message by creating a Message action and adding the action to the validation Failure Message field in the Update action.

  1. Right-click the Actions folder | MDK: New Action | choose MDK Message Actions in Category | click Message Action | Next.

    MDK
  2. Provide the below information:

    Field Value
    Action Name ValidationFailure
    Type Select Message from the dropdown
    Message Email address is not in the correct format recipient @ domain . domaintype
    Title Validate Email
    OKCaption OK
    OnOK --None--
    CancelCaption leave it blank
    OnCancel --None--
    MDK
  3. Click Next and then Finish on the Confirmation step.

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Step 2: Create a new rule

In the MDK editor, you will create a new JavaScript file called EmailValidation.js to handle validation if a @ symbol exists in the email address. In the validation rule, you will grab the data entered by the end-user, validate it and check for the @ symbol then return true if the email address is of a valid format or false if it is not. The returning result of the validation rule can be used in the Update action to determine whether the action succeeds or fails.

You can find more details about writing a Rule.

  1. Right-click the Rules folder | click MDK: New Rule.

    MDK
  2. Enter the Rule name EmailValidation.js, press Enter.

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  3. Replace the generated snippet with below code.

    export default function EmailValidation(context) {
        //The following evaluateTargetPath will retrieve the current value of the email control
        if ((context.evaluateTargetPath('#Control:FCEmail/#Value').indexOf('@')) === -1) {
            //If email value does not contain @ display a validation failure message to the end-user
            context.executeAction('/DemoSampleApp/Actions/ValidationFailure.action');
        } else {
            //If @ is present in the email value, return true to indicate validation is successful
            return true;
        }
    }
    
  4. Save the changes.

    The indexOf() method returns the index within the calling String object of the first occurrence of the specified value and -1, if no occurrence is found.

    In above code there is a reference to ValidationFailure.action , you can navigate directly from here to the MDK file by right clicking on it.
    MDK

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Step 3: Add the validtion rule to the Update entity

Now, that you have created the validation rule, you will add it to the Update action. This will tell the Update action to run the validation rule before saving any data. If the validation rule is successful, the Update action will save the changes as expected. If the validation rule fails, the end-user receives the validation failure message telling them useful information so they can fix the problem before continuing.

  1. Open Customers_UpdateEntity.action by double clicking on the action in the project explorer pane.

  2. Expand the Common Action Properties and select EmailValidation.js rule for Validation Rule field.

    MDK
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Step 4: Deploy and activate the application

Deploy the updated application to your MDK client.

  1. Right-click Application.app and select MDK: Deploy.

    MDK
  2. Select deploy target as Mobile Services.

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    You should see Deploy succeeded message.

    MDK
Which feature of SAP Cloud Platform Mobile Services manages the Mobile Development Kit metadata?
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Step 5: Test the application

Make sure you are choosing the right device platform tab above.

  1. Re-launch the app on your device, you may asked to authenticate with passcode or Biometric authentication. You will see a Confirmation pop-up, click OK.

  2. Update a record with no contain of @ in Email property throws a validation failure message.

    MDKMDK
  1. Re-launch the app on your device, you may asked to authenticate with passcode or Biometric authentication. You will see a Confirmation pop-up, click OK.

  2. Update a record with no contain of @ in Email property throws a validation failure message.

    MDKMDK

Congratulations! You have successfully completed Create Your First Mobile App with the Mobile Development Kit (MDK) mission and you are now all set to Enhance Your First MDK App with Additional Functionalities mission.

For which example, validation rule returns false?
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