Snippet

Domain-Specific Value Objects using Records with Spring Converter

Using immutable Java record types as strong domain primitives prevents primitive obsession. By registering a Spring Converter, HTTP parameters and path variables are automatically parsed into robust, type-safe domain objects.

snippet.java

java

public record IsoCurrencyCode(String code) {
    public IsoCurrencyCode {
        if (code == null || !code.matches("^[A-Z]{3}$")) {
            throw new IllegalArgumentException("Invalid ISO currency: " + code);
        }
    }
}
 
@Component
public class StringToIsoCurrencyConverter implements Converter<String, IsoCurrencyCode> {
    @Override
    public IsoCurrencyCode convert(String source) {
        return new IsoCurrencyCode(source.trim().toUpperCase());
    }
}

spring

Breakdown

public record IsoCurrencyCode(String code) {

Declares an immutable domain value object datatype with a single component field.

if (code == null || !code.matches("^[A-Z]{3}$")) {

Enforces strict domain validation directly within the record's compact constructor.

public class StringToIsoCurrencyConverter implements Converter<String, IsoCurrencyCode> {

Integrates the custom datatype with Spring's ConversionService for seamless binding.

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Domain-Specific Value Objects using Records with Spring Converter

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