Don't have Markdown preview fail for long content by using POST rather than GET.

See https://github.com/gitlabhq/gitlabhq/issues/8611.

CHANGELOG

@@ -61,6 +61,7 @@ v 7.8.0
   - 
   - API: Add support for editing an existing project (Mika Mäenpää and Hannes Rosenögger) 
   - 
+  - Don't have Markdown preview fail for long comments/wiki pages.
   - 
   - When test web hook - show error message instead of 500 error page if connection to hook url was reset
   - Added support for firing system hooks on group create/destroy and adding/removing users to group (Boyan Tabakov)

app/assets/javascripts/dropzone_input.js.coffee

@@ -50,7 +50,7 @@ class @DropzoneInput
         preview.text "Nothing to preview."
       else
         preview.text "Loading..."
-        $.get($(this).data("url"),
+        $.post($(this).data("url"),
           md_text: mdText
         ).success (previewData) ->
           preview.html previewData

config/routes.rb

@@ -209,7 +209,7 @@ Gitlab::Application.routes.draw do
       post :unarchive
       post :upload_image
       post :toggle_star
-      get :markdown_preview
+      post :markdown_preview
       get :autocomplete_sources
     end
 

spec/routing/project_routing_spec.rb

@@ -60,7 +60,7 @@ end
 #                  project GET    /:id(.:format)          projects#show
 #                          PUT    /:id(.:format)          projects#update
 #                          DELETE /:id(.:format)          projects#destroy
-# markdown_preview_project GET    /:id/markdown_preview(.:format) projects#markdown_preview
+# markdown_preview_project POST   /:id/markdown_preview(.:format) projects#markdown_preview
 describe ProjectsController, 'routing' do
   it 'to #create' do
     post('/projects').should route_to('projects#create')
@@ -91,7 +91,7 @@ describe ProjectsController, 'routing' do
   end
 
   it 'to #markdown_preview' do
-    get('/gitlab/gitlabhq/markdown_preview').should(
+    post('/gitlab/gitlabhq/markdown_preview').should(
       route_to('projects#markdown_preview', id: 'gitlab/gitlabhq')
     )
   end