Fix #5267: order[custom] no longer works when only a single ID is being searched

app/logical/concerns/searchable.rb

@@ -249,8 +249,9 @@ module Searchable
   # Post.order_custom("1,2,3") => [post #1, post #2, post #3]
   def order_custom(string)
     operator, ids = RangeParser.parse(string, :integer)
-    return none unless operator == :in
+    return none unless operator in :in | :eq
 
+    ids = Array.wrap(ids)
     in_order_of(:id, ids)
   rescue RangeParser::ParseError
     none

test/functional/application_controller_test.rb

@@ -334,6 +334,14 @@ class ApplicationControllerTest < ActionDispatch::IntegrationTest
       assert_equal(0, response.parsed_body.size)
     end
 
+    should "work if the search[order]=custom param is used with a single id" do
+      tags = create_list(:tag, 2, post_count: 42)
+      get tags_path, params: { search: { id: tags[0].id, order: "custom" } }, as: :json
+
+      assert_response :success
+      assert_equal([tags[0].id], response.parsed_body.pluck("id"))
+    end
+
     should "support the expiry parameter" do
       get posts_path, as: :json, params: { expiry: "1" }
 

test/unit/post_query_builder_test.rb

@@ -1359,7 +1359,7 @@ class PostQueryBuilderTest < ActiveSupport::TestCase
 
       as(create(:gold_user)) do
         assert_tag_match([p2, p1, p3], "id:#{p2.id},#{p1.id},#{p3.id} order:custom")
-        assert_tag_match([], "id:#{p1.id} order:custom")
+        assert_tag_match([p1], "id:#{p1.id} order:custom")
         assert_tag_match([], "id:>0 order:custom")
         assert_tag_match([], "id:1,2 id:2,3 order:custom")
         assert_tag_match([], "order:custom")