@ConditionalOnProperty for branch of values not match

[lowcasz]

A have sample yaml property file:

prefix:
  branch1:
    branch2conditioned:
      branch3a:
        value: true
      barnch3b:
        value: false

I want use @ConditionalOnProperty and create bean when branch2conditioned is defined in application.
It does not work actually.

I tried:
'''
@ConditionalOnProperty("prefix.branch1.branch2conditioned")
@ConditionalOnProperty(prefix ="prefix.branch1", name="branch2conditioned")
@ConditionalOnProperty(prefix ="prefix.branch1.branch2conditioned")
'''
Neither condition match.

[wilkinsona]

Your YAML file above has defined two properties:

• prefix.branch1.branch2conditioned.branch3a.value
• prefix.branch1.branch2conditioned.branch3b.value

prefix.branch1.branch2conditioned doesn't exist as a property so it isn't matched.

If you want a condition that matches when any property whose name begins with prefix.branch1.branch2conditioned has been defined, you'll have to write your own Conditional implementation. It would have to examine all of the properties in the environment to see if any of them begin with prefix.branch1.branch2conditioned. Note that this will be imperfect as some PropertySources in the environment do not extend EnumerablePropertySource which means that they cannot list all of their properties. As such, your condition may not match when it should have done. This might not be a problem in your specific case as it will depend on the property sources that your application uses. JNDI is perhaps the most commonly used non-enumerable source.

[lowcasz]

Actually @ConditionalOnProperty(prefix ="prefix.branch1.branch2conditioned") generates exception due to missing name/value. I think it is great and intuitive place to add extra logic for the case when we have Map<String, ?> in property.
I would like to add this, because it is a common case and at first I thought it was a bug when I am able to map a property to a map.

Mapping to map can be usefull.
For simple example I have done it in this way:

public class PropertiesMapCondition implements Condition {

    private static final String property = "prefix.branch1.branch2conditioned";

    @Override
    public boolean matches(ConditionContext context, @Nullable AnnotatedTypeMetadata metadata) {
        return Binder.get(context.getEnvironment()).bind(property, HashMap.class).isBound();
    }

}

[wilkinsona]

Actually @ConditionalOnProperty(prefix ="prefix.branch1.branch2conditioned") generates exception due to missing name/value

Yes, that's to be expected. I didn't say otherwise above.

When you bind properties to a map, the "property" that you're binding is actually the prefix. It's the keys that are added to the map that are the properties.

I still don't think this is generally useful and has a number of limitations as explained above. As such, it's better suited to a custom condition in your application where you can accommodate any limitations more easily. We can reconsider in the future if things change or there's significant demand for it.