From e286ce515c6552f63f199410ea3f849775d797e2 Mon Sep 17 00:00:00 2001
From: Anton Khorev <tony29@yandex.ru>
Date: Tue, 14 Feb 2023 20:54:40 +0300
Subject: [PATCH] Add limit parameter to api changesets query

---
 app/controllers/api/changesets_controller.rb  | 19 +++++++++++++-
 .../api/changesets_controller_test.rb         | 25 +++++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/app/controllers/api/changesets_controller.rb b/app/controllers/api/changesets_controller.rb
index 56070951a..a08edff53 100644
--- a/app/controllers/api/changesets_controller.rb
+++ b/app/controllers/api/changesets_controller.rb
@@ -19,6 +19,9 @@ module Api
     # Helper methods for checking consistency
     include ConsistencyValidations
 
+    DEFAULT_QUERY_LIMIT = 100
+    MAX_QUERY_LIMIT = 100
+
     ##
     # Return XML giving the basic info about the changeset. Does not
     # return anything about the nodes, ways and relations in the changeset.
@@ -171,7 +174,7 @@ module Api
       changesets = conditions_ids(changesets, params["changesets"])
 
       # sort and limit the changesets
-      changesets = changesets.order("created_at DESC").limit(100)
+      changesets = changesets.order("created_at DESC").limit(result_limit)
 
       # preload users, tags and comments, and render result
       @changesets = changesets.preload(:user, :changeset_tags, :comments)
@@ -383,5 +386,19 @@ module Api
         changesets.where(:id => ids)
       end
     end
+
+    ##
+    # Get the maximum number of results to return
+    def result_limit
+      if params[:limit]
+        if params[:limit].to_i.positive? && params[:limit].to_i <= MAX_QUERY_LIMIT
+          params[:limit].to_i
+        else
+          raise OSM::APIBadUserInput, "Changeset limit must be between 1 and #{MAX_QUERY_LIMIT}"
+        end
+      else
+        DEFAULT_QUERY_LIMIT
+      end
+    end
   end
 end
diff --git a/test/controllers/api/changesets_controller_test.rb b/test/controllers/api/changesets_controller_test.rb
index 979b5d8af..fc24bb8b6 100644
--- a/test/controllers/api/changesets_controller_test.rb
+++ b/test/controllers/api/changesets_controller_test.rb
@@ -1938,6 +1938,31 @@ module Api
       assert_response :bad_request, "should be a bad request since changesets is empty"
     end
 
+    ##
+    # test the query functionality of changesets with the limit parameter
+    def test_query_limit
+      user = create(:user)
+      changeset1 = create(:changeset, :closed, :user => user, :created_at => Time.utc(2008, 1, 1, 0, 0, 0), :closed_at => Time.utc(2008, 1, 2, 0, 0, 0))
+      changeset2 = create(:changeset, :closed, :user => user, :created_at => Time.utc(2008, 2, 1, 0, 0, 0), :closed_at => Time.utc(2008, 2, 2, 0, 0, 0))
+      changeset3 = create(:changeset, :closed, :user => user, :created_at => Time.utc(2008, 3, 1, 0, 0, 0), :closed_at => Time.utc(2008, 3, 2, 0, 0, 0))
+      changeset4 = create(:changeset, :closed, :user => user, :created_at => Time.utc(2008, 4, 1, 0, 0, 0), :closed_at => Time.utc(2008, 4, 2, 0, 0, 0))
+      changeset5 = create(:changeset, :closed, :user => user, :created_at => Time.utc(2008, 5, 1, 0, 0, 0), :closed_at => Time.utc(2008, 5, 2, 0, 0, 0))
+
+      get changesets_path
+      assert_response :success
+      assert_changesets [changeset5, changeset4, changeset3, changeset2, changeset1]
+
+      get changesets_path(:limit => "3")
+      assert_response :success
+      assert_changesets [changeset5, changeset4, changeset3]
+
+      get changesets_path(:limit => "0")
+      assert_response :bad_request
+
+      get changesets_path(:limit => "101")
+      assert_response :bad_request
+    end
+
     ##
     # check that errors are returned if garbage is inserted
     # into query strings
-- 
2.39.5