Added a prop transformer method to the configuration

Author: kieraneglin

lib/inertia_rails/configuration.rb

@@ -12,6 +12,9 @@ class Configuration
       # Allows the user to hook into the default rendering behavior and change it to fit their needs
       component_path_resolver: ->(path:, action:) { "#{path}/#{action}" },
 
+      # A function that transforms the props before they are sent to the client.
+      prop_transformer: ->(props:) { props },
+
       # DEPRECATED: Let Rails decide which layout should be used based on the
       # controller configuration.
       layout: true,
@@ -89,6 +92,10 @@ def component_path_resolver(path:, action:)
       @options[:component_path_resolver].call(path: path, action: action)
     end
 
+    def prop_transformer(props:)
+      @options[:prop_transformer].call(props: props)
+    end
+
     OPTION_NAMES.each do |option|
       unless method_defined?(option)
         define_method(option) do

lib/inertia_rails/renderer.rb

@@ -90,10 +90,13 @@ def merge_props(shared_props, props)
     end
 
     def computed_props
-      merged_props = merge_props(shared_data, props)
-      deep_transform_props(merged_props).tap do |transformed_props|
-        transformed_props[:_inertia_meta] = meta_tags if meta_tags.present?
-      end
+      merge_props(shared_data, props)
+        # This performs the internal work of hydrating/filtering props
+        .then { |props| deep_transform_props(props) }
+        # Then we apply the user-defined prop transformer
+        .then { |props| configuration.prop_transformer(props: props) }
+        # Then we add meta tags after everything since they must not be transformed
+        .tap { |props| props[:_inertia_meta] = meta_tags if meta_tags.present? }
     end
 
     def page