如何将 @ConfigProperties 与 Converter 类一起使用

Question

I tried to implement a custom config type and it worked. However, when I use the custom type with a group of config using the @ConfigProperties it fails to automatically recognize the property by its name and instead treats the property as an object with a nested property.

How can I implement such a behavior correctly? (I am new to Quarkus, so please correct me if I am doing something wrong here)

Here is a code snippet that converts a custom type:

public class Percentage {
    private double percentage;

    public Percentage() {}

    public Percentage(double percentage) {
        this.percentage = percentage;
    }

    public void setPercentage(double percentage) {
        this.percentage = percentage;
    }

    public double getPercentage() {
        return this.percentage;
    }
}

@Priority(300)
public class PercentageConverter implements Converter<Percentage> {

    @Override
    public Percentage convert(String value) {
        int percentIndex = value.indexOf("%");
        return new Percentage(Double.parseDouble(value.substring(0, percentIndex - 1)));
    }

}

/// this works ------

public class Hello {

    @ConfigProperty(name = "custom.vat")
    Percentage vat;

    public Hello () {
    }

   // ..... 

}


/// however, this fails

@ConfigProperties(prefix = "custom")
public class CustomConfig {

    public Percentage vat;

    public Percentage profit;

}

javax.enterprise.inject.spi.DeploymentException: No config value of type [double] exists for: custom.vat.percentage
    at io.quarkus.arc.runtime.ConfigRecorder.validateConfigProperties(ConfigRecorder.java:39)

Answer 1

Unfortunately, I believe this does not work because Quarkus @ConfigProperties, handles these cases as if they were subgroups and try to map nested properties with the configuration (and not use the Converter).

Feel free to open up an issue in Quarkus GH if you feel this should change: https://github.com/quarkusio/quarkus/issues

Alternately, you can use SR Config @ConfigMapping: https://smallrye.io/docs/smallrye-config/mapping/mapping.html . It covers a few more cases, including direct Conversion and in the future it may replace Quarkus @ConfigProperties.