pre-render blog::post content

app/models/blog/post.rb

@@ -12,6 +12,8 @@ class Blog::Post < ApplicationRecord
 
   scope :published, -> { active.where.not(published_at: nil) }
 
+  before_save :render_markdown,
+    if: -> {content_changed? || content.present? != content_rendered.present?}
 
   # Not using a scope here because of 'first'
   def self.last_within days: 7.days
@@ -30,4 +32,11 @@ def next
     Blog::Post.published.where("created_at > ?", created_at)
       .order(created_at: :asc).where.not(id: id).first
   end
+
+  def render_markdown
+    renderer = Redcarpet::Render::HTML.new(with_toc_data: true)
+    assign_attributes({
+      content_rendered: Redcarpet::Markdown.new(renderer).render(content)
+    })
+  end
 end

app/views/blog/posts/show.html.haml

@@ -13,10 +13,7 @@
     = l(@post.published_at, format: :worded)
 
 .container.content
-  -# TODO do not render markdown in the view
-  -#= @post.content
-  - renderer = Redcarpet::Render::HTML.new(with_toc_data: true)
-  != Redcarpet::Markdown.new(renderer).render(@post.content)
+  != @post.content_rendered
 
 %hr
 

db/migrate/20201009052202_add_content_rendered_to_blog_post.rb

@@ -0,0 +1,10 @@
+# SPDX-FileCopyrightText: 2020 Felix Wolfsteller
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+class AddContentRenderedToBlogPost < ActiveRecord::Migration[6.0]
+  def change
+    add_column :blog_posts, :content_rendered, :text
+    Blog::Post.find_each {|p| p.save!}
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_10_07_174709) do
+ActiveRecord::Schema.define(version: 2020_10_09_052202) do
 
   create_table "active_storage_attachments", force: :cascade do |t|
     t.string "name", null: false
@@ -53,6 +53,7 @@
     t.datetime "updated_at", precision: 6, null: false
     t.text "summary"
     t.datetime "published_at"
+    t.text "content_rendered"
     t.index ["slug"], name: "index_blog_posts_on_slug", unique: true
   end