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Feature Flags

Feature flags are a mechanism that allows you to enable and test experimental features. You can also use this mechanism to switch temporarily back to legacy and deprecated behavior, to give yourself more time to migrate your applications not to use them, before they’re removed.

The following listings contain all experimental and legacy features. They’re also listed in the com.vaadin.experimental.FeatureFlags (Javadoc) class.

Experimental Features

enforceFieldValidation

Enforce client / constraint / binder validation. Learn more

spreadsheetComponent

Spreadsheet component (Pro).

collaborationEngineBackend

Collaboration Kit backend for clustering support. Learn more

mapComponent

Map component (Pro).

Since Vaadin 23.2, the Map component can be used without the feature flag.

Legacy Features

oldLicenseChecker

Old license checker.

webpackForFrontendBuild

Use webpack for front-end builds. Learn more

Managing Feature Flags

Feature flags can be managed in different ways: by using Vaadin Developer Tools; by editing the feature flags properties file; or by setting Java system properties. Each of these methods is described in the sub-sections that follow. However, remember that system properties always have the highest priority. Since they aren’t written into the feature flags properties file, they’re valid only for a single execution.

Using Vaadin Developer Tools

It’s easy to manage feature flags using Vaadin Developer Tools. When running your browser in development mode, click the Vaadin Developer Tools icon button in your application — it’s located at bottom right corner.

Next, open the Experimental Features tab and then click the toggle buttons to enable or disable features.

When you’re finished, restart the application for your changes to take effect.

Editing the Properties File

As mentioned above, you can also manage feature flags by editing the properties file. To do so by this method, edit the src/main/resources/vaadin-featureflags.properties file in your application folder — or create the file if it doesn’t already exist.

When you have that file open, add a line for each feature in the format of com.vaadin.experimental.<FEATURE_NAME>=true. Below is an example of how this might look:

+ .vaadin-featureflags.properties

com.vaadin.experimental.enforceFieldValidation=true

To disable a feature, remove the corresponding line or set its value to false.

When you’re finished enabling or disabling feature flags, save the properties file and restart the application.

Setting Java System Properties

The last method for managing feature flags is to set the Java system properties. From the command-line, you would use the IDE launch configuration or a tool configuration — such as, Spring Boot Maven plugin — to set a system property for each feature flag to be enabled or disabled.

The property name should be in the format vaadin.<FEATURE_NAME>, like so:

-Dvaadin.enforceFieldValidation=true

To temporarily disable a feature, set its property value to false, like this:

-Dvaadin.enforceFieldValidation=false