Use Rails' index_by where it makes sense (#15542)

* Use Rails' index_by where it makes sense

* Fix tests

Co-authored-by: Claire <claire.github-309c@sitedethib.com>

app/models/account.rb

@@ -273,7 +273,7 @@ class Account < ApplicationRecord
   end
 
   def tags_as_strings=(tag_names)
-    hashtags_map = Tag.find_or_create_by_names(tag_names).each_with_object({}) { |tag, h| h[tag.name] = tag }
+    hashtags_map = Tag.find_or_create_by_names(tag_names).index_by(&:name)
 
     # Remove hashtags that are to be deleted
     tags.each do |tag|

app/models/notification.rb

@@ -96,7 +96,7 @@ class Notification < ApplicationRecord
 
       return if account_ids.empty?
 
-      accounts = Account.where(id: account_ids).includes(:account_stat).each_with_object({}) { |a, h| h[a.id] = a }
+      accounts = Account.where(id: account_ids).includes(:account_stat).index_by(&:id)
 
       cached_items.each do |item|
         item.from_account = accounts[item.from_account_id]

app/models/setting.rb

@@ -40,7 +40,7 @@ class Setting < RailsSettings::Base
 
     def all_as_records
       vars    = thing_scoped
-      records = vars.each_with_object({}) { |r, h| h[r.var] = r }
+      records = vars.index_by(&:var)
 
       default_settings.each do |key, default_value|
         next if records.key?(key) || default_value.is_a?(Hash)

app/models/status.rb

@@ -301,7 +301,7 @@ class Status < ApplicationRecord
 
       return if account_ids.empty?
 
-      accounts = Account.where(id: account_ids).includes(:account_stat).each_with_object({}) { |a, h| h[a.id] = a }
+      accounts = Account.where(id: account_ids).includes(:account_stat).index_by(&:id)
 
       cached_items.each do |item|
         item.account = accounts[item.account_id]

app/models/trending_tags.rb

@@ -91,7 +91,7 @@ class TrendingTags
 
       tags = Tag.where(id: tag_ids)
       tags = tags.trendable if filtered
-      tags = tags.each_with_object({}) { |tag, h| h[tag.id] = tag }
+      tags = tags.index_by(&:id)
 
       tag_ids.map { |tag_id| tags[tag_id] }.compact.take(limit)
     end