Accept hash-like inputs in from_hash (#104)

Normalize hash inputs via to_hash in from_hash/add_from_hash to support
Rails HashWithIndifferentAccess without adding an ActiveSupport dependency.
Includes coverage and documentation updates.

Author: evolve75

API-CHANGES.md

@@ -26,6 +26,10 @@ smooth transition to the new APIs.
   [Tree::TreeNode#print_tree_to_s][print_tree_to_s] returns the formatted
   output as a string.
 
+* Hash conversion now accepts hash-like inputs (objects responding to
+  `to_hash`) to improve interoperability with frameworks such as Rails
+  (see #104).
+
 ## Release 2.2.0 Changes
 
 * [Tree::TreeNode#add][add] now raises `ArgumentError` when attempting to add

History.md

@@ -19,6 +19,9 @@
 * Allow `print_tree` to write to a custom IO and add `print_tree_to_s` for
   string output.
 
+* Accept hash-like inputs (`to_hash`) in hash conversion to support Rails
+  `HashWithIndifferentAccess` data (see #104).
+
 ### 2.2.1pre / 2026-02-07
 
 * Simplified development dependency constraints while maintaining Ruby 2.7+

lib/tree/utils/hash_converter.rb

@@ -54,6 +54,12 @@ def self.included(base)
       # class methods on any class mixing in the {Tree::Utils::HashConverter}
       # module.
       module ClassMethods
+        def normalize_hash_input(value)
+          return value.to_hash if value.respond_to?(:to_hash)
+
+          value
+        end
+
         # Factory method builds a {Tree::TreeNode} from a +Hash+.
         #
         # This method will interpret each key of your +Hash+ as a {Tree::TreeNode}.
@@ -98,11 +104,13 @@ module ClassMethods
         #                        values that are not hashes or nils.
 
         def from_hash(hash)
+          hash = normalize_hash_input(hash)
           raise ArgumentError, 'Argument must be a type of hash' unless hash.is_a?(Hash)
 
           raise ArgumentError, 'Hash must have one top-level element' if hash.size != 1
 
           root, children = hash.first
+          children = normalize_hash_input(children)
 
           case children
           in Hash | nil
@@ -145,6 +153,7 @@ def from_hash(hash)
       # @return [Array] Array of child nodes added
       # @see ClassMethods#from_hash
       def add_from_hash(children)
+        children = self.class.normalize_hash_input(children)
         raise ArgumentError, 'Argument must be a type of hash' unless children.is_a?(Hash)
 
         child_nodes = []

test/test_tree_conversion.rb

@@ -136,6 +136,25 @@ def test_from_hash_with_nils
       assert_equal(2, interior_node.children.count)
     end
 
+    def test_from_hash_accepts_hash_like_inputs
+      hash_like = Class.new do
+        def initialize(payload)
+          @payload = payload
+        end
+
+        def to_hash
+          @payload
+        end
+      end
+
+      input = hash_like.new({ A: hash_like.new({ B: nil }) })
+      tree = Tree::TreeNode.from_hash(input)
+
+      assert_equal(:A, tree.name)
+      assert_equal(true, tree.root?)
+      assert_equal(true, tree[:B].leaf?)
+    end
+
     def test_add_from_hash
       tree = Tree::TreeNode.new(:A)