[FIXED] Nested Spring configuration (ConfigurationProperties) in records

Issue

How can one map an application.yaml configuration with nested properties to a similar record structure in Java?

E.g., if we have the following yaml:

foo:
    bar:
        something: 42

    baz:
        otherThing: true

    color: blue

The desired record structure would be something along the lines of:

@ConfigurationProperties(prefix = "foo")
@ConstructorBinding
public record Foo(
    Bar bar,
    Baz baz,
    String color
) {}

// ---

@ConfigurationProperties(prefix = "foo.bar")
@ConstructorBinding
public record Bar(
    int something
) {}

// ---

@ConfigurationProperties(prefix = "foo.baz")
@ConstructorBinding
public record Baz(
    boolean otherThing
) {}

Solution

You don't need @ConfigurationProperties for each nested class. It only for the root class (Foo.class). Then make the Foo as Spring Bean by inserting @Component above the class or put @ConfigurationPropertiesScan on the Application class.

Answered By - Ferry
Answer Checked By - David Marino (JavaFixing Volunteer)