Class MetadataParameterResolver

java.lang.Object
io.fluxzero.common.handling.TypedParameterResolver<Object>
io.fluxzero.sdk.tracking.handling.MetadataParameterResolver
All Implemented Interfaces:
ParameterResolver<Object>
public class MetadataParameterResolver extends TypedParameterResolver<Object>
Resolves handler method parameters of type Metadata.

This resolver can inject metadata into handler methods in two ways:

  • If the message being handled implements HasMetadata, its metadata is directly returned.
  • Otherwise, the metadata is extracted from the current DeserializingMessage (if available).

Example handler: 

@HandleCommand
public void handle(MyCommand command, Metadata metadata) {
    String user = metadata.get("userId");
}

  • Constructor Details

    • MetadataParameterResolver

      public MetadataParameterResolver()

  • Method Details

    • resolve

      public Function<Object,Object> resolve(Parameter p, Annotation methodAnnotation)
      Description copied from interface: ParameterResolver
      Resolves a Parameter of a handler method into a value function based on the given message.

      If the parameter cannot be resolved by this resolver and ParameterResolver.matches(Parameter, Annotation, M) is not implemented, this method must return null.

      Parameters:
      p - the parameter to resolve
      methodAnnotation - the annotation present on the handler method (e.g., @HandleEvent)
      Returns:
      a function that takes a message and returns a value to be injected into the method parameter, or null if the parameter cannot be resolved and ParameterResolver.matches(Parameter, Annotation, M) is not implemented.

    • prepare

      public Function<Object,Object> prepare(Parameter parameter, Annotation methodAnnotation)
      Description copied from interface: ParameterResolver
      Prepares a resolver function when this resolver can determine compatibility from the parameter and method annotation alone.

      The default returns null, which keeps resolution message-dependent. Implementations should override this only when ParameterResolver.matches(Parameter, Annotation, Object) would always be true for the supplied parameter, regardless of the message instance. Dynamic resolvers such as payload, trigger, or entity resolvers should keep the default behavior.

      Parameters:
      parameter - the parameter to resolve
      methodAnnotation - the annotation present on the handler method
      Returns:
      a prepared resolver, or null when resolution must remain message-dependent