add is_only_child? instance method

README.md

@@ -1,5 +1,5 @@
 #ActsAsCategory
-[![Build Status](https://secure.travis-ci.org/mbrookes/acts_as_category.svg?branch=master)](http://travis-ci.org/mbrookes/acts_as_tree)
+[![Build Status](https://secure.travis-ci.org/mbrookes/acts_as_category.svg?branch=master)](http://travis-ci.org/mbrookes/acts_as_category)
 [![Gem Version](https://badge.fury.io/rb/acts_as_category.svg)](http://badge.fury.io/rb/acts_as_category)
 
       acts_as_category (Version 2.0 beta)
@@ -228,8 +228,9 @@ RDoc.
   root1.parent         # Returns nil, because root has no parent
 
   child1.children      # Returns an array with [subchild1, subchild2]
-  child1.children_ids  # Returns the same array, but ids instead of categories [3, 4]
-  child1.children?     # Returns true as child1 has children
+  child1.child_ids     # Returns the same array, but ids instead of categories [3, 4]
+  child1.has_children? # Returns true as child1 has children
+  child1.is_childless? # Returns false as child1 has children
 
   subchild1.ancestors      # Returns an array with [child1, root1]
   subchild1.ancestors_ids  # Returns the same array, but ids instead of categories [2, 1]
@@ -241,6 +242,7 @@ RDoc.
 
   root1.siblings           # Returns an array with all siblings [root2]
   root1.has_siblings?      # Returns true
+  child1.is_only_child?    # Returns true (alias .only_child?)
   root1.siblings_ids       # Returns an array with all siblings ids [5]
   child1.siblings          # Returns an empty array [], because it has no siblings
 

lib/acts_as_category/acts_as_category.rb

@@ -295,11 +295,16 @@ def children_ids
       self.children.each { |child| children_ids << child.id if child.permitted? } unless self.children.empty?
       children_ids
     end
+    alias_method :child_ids, :children_ids
 
     def has_children?
         !self.children.empty?
     end
 
+    def is_childless?
+      !has_children?
+    end
+
     # Returns list of ancestors, disregarding any permissions
     def ancestors
       node, nodes = self, []
@@ -353,10 +358,7 @@ def root
     def root?
       self.parent ? false : true
     end
-
-    def is_root?
-      root?
-    end
+    alias_method :is_root?, :root?
 
     # Returns all siblings of the current node, respecting permitted/hidden categories
     def siblings
@@ -369,6 +371,11 @@ def has_siblings?
       !siblings.empty?
     end
 
+    def is_only_child?
+      !has_siblings?
+    end
+    alias_method :only_child?, :is_only_child?
+
     # Returns ids of all siblings of the current node, respecting permitted/hidden categories
     def siblings_ids
       self_and_siblings_ids - [self.id]

test/category_test.rb

@@ -222,6 +222,11 @@ def test_has_children?
     refute @n221.has_children?
   end
 
+  def test_is_childless?
+    refute @n22.is_childless?
+    assert @n221.is_childless?
+  end
+
   def test_has_siblings_permissions
     assert @n221.update_attribute('my_hidden', true)
     refute @n22.has_children?
@@ -254,6 +259,18 @@ def test_children_ids
     assert_equal [], @n221.children_ids
   end
 
+  def test_child_ids
+    assert_equal [@n11.id], @n1.child_ids
+    assert_equal [@n21.id, @n22.id], @n2.child_ids
+    assert_equal [], @n3.child_ids
+    assert_equal [@n111.id], @n11.child_ids
+    assert_equal [], @n111.children_ids
+    assert_equal [@n211.id], @n21.child_ids
+    assert_equal [@n221.id], @n22.child_ids
+    assert_equal [], @n211.child_ids
+    assert_equal [], @n221.child_ids
+  end
+
   def test_children_ids_with_permissions
     assert @n22.update_attribute('my_hidden', true)
     assert_equal [@n11.id], @n1.children_ids
@@ -464,6 +481,11 @@ def test_has_siblings?
     assert @n21.has_siblings?
   end
 
+  def test_only_child?
+    assert @n11.only_child?
+    refute @n21.only_child?
+  end
+
   def test_has_siblings_permissions
     assert @n2.update_attribute('my_hidden', true)
     refute @n21.has_siblings?