Spring Boot bind @Value to Enum case insensitive

@Value and @ConfigurationProperties features do not match. I couldn't stress enough how @ConfigurationProperties is superior.

First, you get to design your configuration in a simple POJO that you can inject wherever you want (rather than having expressions in annotation that you can easily break with a typo). Second, the meta-data support means that you can very easily get auto-completion in your IDE for your own keys.

And finally, the relaxed binding described in the doc only applies to @ConfigurationProperties. @Value is a Spring Framework feature and is unaware of relaxed binding. We intend to make that more clear in the doc.

TL;DR abc works with @ConfigurationProperties but won't with @Value.

A problem with ConfigurationPropertis (afaik) is that you cannot use constructor injection, and your class has to be mutable.

A workaround (or hack if you like) would be to use SpEL to uppercase the property before looking it up, like this:

@Value("#{'${custom.property}'.toUpperCase()}") Property property

This should work since enums instances are constants, and should always be defined in uppercase: https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html

In a practical world, this works....

public enum Property {    A, a    AB, ab,    ABC, abc,    ABCD, abcd,    ABCDE, abcde;     public boolean isA() {        return this.equals(A) || this.equals(a);    }    public boolean isAB() {        return this.equals(AB) || this.equals(ab);    }    ...etc...}

..although this does break the principle of the enum!