Spring Boot @ConditionalOnProperty Example

Spring Boot provides a powerful and flexible way to configure your application using properties. These properties can be defined in various ways, including in application.properties or application.yml files, environment variables, or even through command-line arguments. In some cases, you may want certain parts of your application to be conditionally enabled or disabled based on these properties. This is where @ConditionalOnProperty comes into play.

In this blog post, we’ll explore the @ConditionalOnProperty annotation in Spring Boot and provide an example of how you can use it to conditionally enable or disable beans in your application.

What is @ConditionalOnProperty?

@ConditionalOnProperty is a conditional annotation in Spring Boot that allows you to control the bean registration based on the presence or absence of specific properties in your configuration. It provides a way to configure your application to behave differently depending on the values of these properties.

The annotation is often used in combination with the spring.boot.autoconfigure.condition package to conditionally enable auto-configuration classes and beans. It provides a concise way to conditionally activate certain parts of your application’s configuration.

Using @ConditionalOnProperty

To use @ConditionalOnProperty, you need to annotate a class or method with it, providing the property name(s) as parameters. The annotation can be used in various ways, depending on your use case. Here’s a basic example:

import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.stereotype.Component;

@Component
@ConditionalOnProperty(name = "myapp.feature.enabled", havingValue = "true")
public class MyFeatureEnabledComponent {
    // Your component code here
}

In this example, we’ve annotated a component with @ConditionalOnProperty. The name attribute specifies the name of the property we want to check, and havingValue specifies the expected value of that property for this component to be enabled. If the property myapp.feature.enabled is set to true in the application’s configuration, this component will be registered as a bean. If the property is missing or has any value other than true, the component will not be registered.

You can also use additional attributes like matchIfMissing to define the behavior when the property is missing entirely. By default, if the property is missing, the bean will not be created. However, you can set matchIfMissing = true to create the bean when the property is missing.

@ConditionalOnProperty(name = "myapp.feature.enabled", havingValue = "true", matchIfMissing = true)

Example: Conditional Database Configuration

Let’s consider a practical example where we want to conditionally enable a specific database configuration based on a property. Assume that we have two different database configurations, one for development and another for production, and we want to select the appropriate configuration based on the spring.profiles.active property.

Create two database configuration classes, one for development and one for production:

@Configuration
@Profile("dev")
public class DevDatabaseConfig {
    // Development database configuration
}

@Configuration
@Profile("prod")
public class ProdDatabaseConfig {
    // Production database configuration
}

Use @ConditionalOnProperty to conditionally enable the appropriate configuration based on the active profile:

@Configuration
@ConditionalOnProperty(name = "spring.profiles.active", havingValue = "dev")
public class ConditionalDatabaseConfig {
    // Empty class used only for conditional bean registration
}

In this example, we have defined two database configuration classes, one for the “dev” profile and another for the “prod” profile. We use the @Profile annotation to specify which configuration should be active for each profile. Then, we create a ConditionalDatabaseConfig class annotated with @ConditionalOnProperty that depends on the spring.profiles.active property. When the active profile is “dev,” the ConditionalDatabaseConfig class will be registered, enabling the development database configuration. Otherwise, it won’t be registered.

By using @ConditionalOnProperty, we can ensure that the appropriate database configuration is automatically selected based on the active profile, making our application more flexible and maintainable.

Conclusion

In this blog post, we’ve explored the @ConditionalOnProperty annotation in Spring Boot and how it can be used to conditionally enable or disable beans and configurations in your application. This feature is particularly useful when you want to control the behavior of your application based on properties defined in your configuration files. By using @ConditionalOnProperty, you can make your application more adaptable and responsive to different deployment scenarios.

As you continue to work with Spring Boot, keep in mind that conditional annotations like @ConditionalOnProperty are powerful tools for managing the behavior of your application, allowing you to customize it based on runtime properties and conditions.