Use Enumerable#index_by where possible

app/services/merge_requests/get_urls_service.rb

@@ -23,10 +23,7 @@ module MergeRequests
 
     def opened_merge_requests_from_source_branches(branches)
       merge_requests = MergeRequest.from_project(project).opened.from_source_branches(branches)
-      merge_requests.inject({}) do |hash, mr|
-        hash[mr.source_branch] = mr
-        hash
-      end
+      merge_requests.index_by(&:source_branch)
     end
 
     def get_branches(changes)

app/services/users/refresh_authorized_projects_service.rb

@@ -93,9 +93,7 @@ module Users
     end
 
     def current_authorizations_per_project
-      current_authorizations.each_with_object({}) do |row, hash|
-        hash[row.project_id] = row
-      end
+      current_authorizations.index_by(&:project_id)
     end
 
     def current_authorizations

lib/banzai/filter/abstract_reference_filter.rb

@@ -239,18 +239,13 @@ module Banzai
       # path.
       def projects_per_reference
         @projects_per_reference ||= begin
-          hash = {}
           refs = Set.new
 
           references_per_project.each do |project_ref, _|
             refs << project_ref
           end
 
-          find_projects_for_paths(refs.to_a).each do |project|
-            hash[project.path_with_namespace] = project
-          end
-
-          hash
+          find_projects_for_paths(refs.to_a).index_by(&:full_path)
         end
       end
 

lib/banzai/filter/user_reference_filter.rb

@@ -74,10 +74,7 @@ module Banzai
       # The keys of this Hash are the namespace paths, the values the
       # corresponding Namespace objects.
       def namespaces
-        @namespaces ||=
-          Namespace.where_full_path_in(usernames).each_with_object({}) do |row, hash|
-            hash[row.full_path] = row
-          end
+        @namespaces ||= Namespace.where_full_path_in(usernames).index_by(&:full_path)
       end
 
       # Returns all usernames referenced in the current document.

lib/banzai/reference_parser/base_parser.rb

@@ -134,9 +134,7 @@ module Banzai
         ids = unique_attribute_values(nodes, attribute)
         rows = collection_objects_for_ids(collection, ids)
 
-        rows.each_with_object({}) do |row, hash|
-          hash[row.id] = row
-        end
+        rows.index_by(&:id)
       end
 
       # Returns an Array containing all unique values of an attribute of the