wikis: disallow renaming unless tag is empty (fix #2964).

app/models/tag_alias.rb

@@ -254,9 +254,7 @@ class TagAlias < ActiveRecord::Base
     if antecedent_wiki.present? 
       if WikiPage.titled(consequent_name).blank?
         CurrentUser.scoped(creator, creator_ip_addr) do
-          antecedent_wiki.update_attributes(
-            :title => consequent_name
-          )
+          antecedent_wiki.update(title: consequent_name, skip_secondary_validations: true)
         end
       else
         message = "The tag alias [[#{antecedent_name}]] -> [[#{consequent_name}]] (alias ##{id}) has conflicting wiki pages. [[#{consequent_name}]] should be updated to include information from [[#{antecedent_name}]] if necessary."

app/models/wiki_page.rb

@@ -10,9 +10,11 @@ class WikiPage < ActiveRecord::Base
   belongs_to :updater, :class_name => "User"
   validates_uniqueness_of :title, :case_sensitive => false
   validates_presence_of :title
+  validate :validate_rename
   validate :validate_locker_is_builder
   validate :validate_not_locked
-  attr_accessible :title, :body, :is_locked, :is_deleted, :other_names
+  attr_accessor :skip_secondary_validations
+  attr_accessible :title, :body, :is_locked, :is_deleted, :other_names, :skip_secondary_validations
   has_one :tag, :foreign_key => "name", :primary_key => "title"
   has_one :artist, lambda {where(:is_active => true)}, :foreign_key => "name", :primary_key => "title"
   has_many :versions, lambda {order("wiki_page_versions.id ASC")}, :class_name => "WikiPageVersion", :dependent => :destroy
@@ -120,6 +122,15 @@ class WikiPage < ActiveRecord::Base
     end
   end
 
+  def validate_rename
+    return if !title_changed? || skip_secondary_validations
+
+    tag_was = Tag.find_by_name(Tag.normalize_name(title_was))
+    if tag_was.present? && tag_was.post_count > 0
+      errors.add(:title, "cannot be changed: '#{tag_was.name}' still has #{tag_was.post_count} posts. Move the posts and update any wikis linking to this page first.")
+    end
+  end
+
   def revert_to(version)
     if id != version.wiki_page_id
       raise RevertError.new("You cannot revert to a previous version of another wiki page.")
@@ -145,6 +156,10 @@ class WikiPage < ActiveRecord::Base
     self.other_names = normalized_other_names.uniq.join(" ")
   end
 
+  def skip_secondary_validations=(value)
+    @skip_secondary_validations = (value == true || value == "1")
+  end
+
   def creator_name
     User.id_to_name(creator_id).tr("_", " ")
   end

app/views/wiki_pages/_form.html.erb

@@ -2,17 +2,11 @@
   <%= error_messages_for("wiki_page") %>
 
   <%= simple_form_for(@wiki_page) do |f| %>
-    <div class="input">
-      <label for="wiki_page_title">Title</label>
-      <% if @wiki_page.new_record? %>
-        <%= text_field "wiki_page", "title" %>
-      <% elsif CurrentUser.user.is_builder? %>
-        <%= text_field "wiki_page", "title" %>
-        <span class="hint">Change to rename this wiki page</span>
-      <% else %>
-        <p><%= @wiki_page.title %></p>
-      <% end %>
-    </div>
+    <% if @wiki_page.new_record? %>
+      <%= f.input :title, error: false %>
+    <% else %>
+      <%= f.input :title, error: false, hint: "Change to rename this wiki page. Move the tag and update any wikis linking to this page first." %>
+    <% end %>
 
     <%= f.input :other_names, :as => :text, :label => "Other names (<a href='/wiki_pages/help:translated_tags'>view help</a>)".html_safe, :hint => "Names used for this tag on other sites such as Pixiv. Separate with spaces." %>
 
@@ -26,6 +20,10 @@
       <%= f.input :is_locked, :label => "Locked" %>
     <% end %>
 
+    <% if @wiki_page.errors[:title].present?  %>
+      <%= f.input :skip_secondary_validations, as: :boolean, label: "Force rename", hint: "Ignore the renaming requirements" %>
+    <% end %>
+
     <%= f.button :submit, "Submit", :data => { :disable_with => "Submitting..." } %>
     <%= dtext_preview_button "wiki_page", "body" %>
   <% end %>

test/functional/wiki_pages_controller_test.rb

@@ -99,7 +99,8 @@ class WikiPagesControllerTest < ActionController::TestCase
 
     context "update action" do
       setup do
-        @wiki_page = FactoryGirl.create(:wiki_page)
+        @tag = FactoryGirl.create(:tag, name: "foo", post_count: 42)
+        @wiki_page = FactoryGirl.create(:wiki_page, title: "foo")
       end
 
       should "update a wiki_page" do
@@ -107,6 +108,18 @@ class WikiPagesControllerTest < ActionController::TestCase
         @wiki_page.reload
         assert_equal("xyz", @wiki_page.body)
       end
+
+      should "not rename a wiki page with a non-empty tag" do
+        post :update, {:id => @wiki_page.id, :wiki_page => {:title => "bar"}}, {:user_id => @user.id}
+
+        assert_equal("foo", @wiki_page.reload.title)
+      end
+
+      should "rename a wiki page with a non-empty tag if secondary validations are skipped" do
+        post :update, {:id => @wiki_page.id, :wiki_page => {:title => "bar", :skip_secondary_validations => "1"}}, {:user_id => @user.id}
+
+        assert_equal("bar", @wiki_page.reload.title)
+      end
     end
 
     context "destroy action" do