Handling Optional Configuration Properties in Spring Boot

It sounds like you’re on the right track with your use of @ConfigurationProperties! When it comes to optional configuration properties in Spring Boot, there are a few ways you can handle it without your application crashing during startup.

1. Use Optional

Using Optional is a valid approach. This way, if a property isn’t set, it’ll simply be an empty Optional instead of causing an error. Here’s an example:

import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "app")
public class AppProperties {
    private Optional name = Optional.empty();
    private Optional timeout = Optional.empty();

    // Getters and Setters
}

2. Make Fields Nullable

If using Optional feels too complex, you can also make the fields in your config class nullable:

public class AppProperties {
    private String name;
    private Integer timeout;

    // Getters and Setters
}

This way, if a property isn’t set, it will just be null. Just be cautious to handle null checks in your code!

3. Default Values

Setting sensible defaults directly in your code can be a good practice. It helps ensure your application runs smoothly even if some properties are missing. For example:

@Value("${app.name:DefaultName}")
private String name;

@Value("${app.timeout:3000}")
private int timeout;

This would set name to "DefaultName" and timeout to 3000 if they’re not specified in application.properties.

Another common approach is to use Spring’s @PostConstruct annotation to set defaults after properties are loaded:

@PostConstruct
public void init() {
    if (this.name == null) {
        this.name = "DefaultName";
    }
}

4. Summary

There isn’t a single “best” way—it’s mostly about what fits your application best. Optional properties can help with clarity, while sensible defaults ensure robustness. Just remember to document how your properties are expected to work, as it helps other developers (and your future self) understand what’s happening!

Hope this helps, and happy coding!