Fix the find filter to return nil when filtering empty arrays

History.md

@@ -2,9 +2,14 @@
 
 ## 5.8.0 (unreleased)
 
+## 5.7.1 2025-01-23
+
+* Fix the `find` filter to return `nil` when filtering empty arrays
+
 ## 5.7.0 2025-01-16
 
 ### Features
+
 * Add `find`, `find_index`, `has`, and `reject` filters to arrays
 * Compatibility with Ruby 3.4
 

lib/liquid/standardfilters.rb

@@ -472,7 +472,7 @@ module Liquid
     # @liquid_syntax array | find: string, string
     # @liquid_return [untyped]
     def find(input, property, target_value = nil)
-      filter_array(input, property, target_value) { |ary, &block| ary.find(&block) }
+      filter_array(input, property, target_value, nil) { |ary, &block| ary.find(&block) }
     end
 
     # @liquid_public_docs
@@ -969,10 +969,10 @@ module Liquid
 
     attr_reader :context
 
-    def filter_array(input, property, target_value, &block)
+    def filter_array(input, property, target_value, default_value = [], &block)
       ary = InputIterator.new(input, context)
 
-      return [] if ary.empty?
+      return default_value if ary.empty?
 
       block.call(ary) do |item|
         if target_value.nil?

lib/liquid/version.rb

@@ -2,5 +2,5 @@
 # frozen_string_literal: true
 
 module Liquid
-  VERSION = "5.7.0"
+  VERSION = "5.7.1"
 end

test/integration/standard_filter_test.rb

@@ -157,6 +157,10 @@ class StandardFiltersTest < Minitest::Test
     assert_equal([], @filters.slice(input, -(1 << 63), 6))
   end
 
+  def test_find_on_empty_array
+    assert_nil(@filters.find([], 'foo', 'bar'))
+  end
+
   def test_truncate
     assert_equal('1234...', @filters.truncate('1234567890', 7))
     assert_equal('1234567890', @filters.truncate('1234567890', 20))
@@ -1042,6 +1046,18 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
   end
 
+  def test_find_with_empty_arrays
+    template = <<~LIQUID
+      {%- assign product = products | find: 'title.content', 'Not found' -%}
+      {%- unless product -%}
+        Product not found.
+      {%- endunless -%}
+    LIQUID
+    expected_output = "Product not found."
+
+    assert_template_result(expected_output, template, { "products" => [] })
+  end
+
   def test_find_index_with_value
     products = [
       { "title" => "Pro goggles",    "price" => 1299 },