Add mass conversion task

lib/mix/tasks/convert_to_markdown.ex

@@ -0,0 +1,54 @@
+defmodule Mix.Tasks.ConvertToMarkdown do
+  use Mix.Task
+
+  import Ecto.Query
+  alias Philomena.Repo
+  alias Philomena.Batch
+  alias PhilomenaWeb.TextileMarkdownRenderer
+
+  @modules [
+    {Philomena.Badges.Badge, [:description]},
+    {Philomena.Channels.Channel, [:description]},
+    {Philomena.Comments.Comment, [:body]},
+    {Philomena.Commissions.Commission, [:contact, :information, :will_create, :will_not_create]},
+    {Philomena.Commissions.Item, [:description, :add_ons]},
+    {Philomena.Conversations.Message, [:body]},
+    {Philomena.DnpEntries.DnpEntry, [:conditions, :reason, :instructions]},
+    {Philomena.Filters.Filter, [:description]},
+    {Philomena.Galleries.Gallery, [:description]},
+    {Philomena.Images.Image, [:description]},
+    {Philomena.ModNotes.ModNote, [:body]},
+    {Philomena.Posts.Post, [:body]},
+    {Philomena.Reports.Report, [:report]},
+    {Philomena.Tags.Tag, [:description]},
+    {Philomena.Users.User, [:description, :scratchpad]},
+  ]
+
+  @shortdoc "Rewrites all database rows from Textile to Markdown."
+  @requirements ["app.start"]
+  @impl Mix.Task
+  def run(args) do
+    if Mix.env() == :prod and not Enum.member?(args, "--i-know-what-im-doing") do
+      raise "do not run this task in production unless you know what you're doing"
+    end
+
+    Enum.map(@modules, fn {mod, fields} ->
+      Batch.record_batches(mod, fn batch ->
+        Enum.map(batch, fn item ->
+          updates = Enum.reduce(fields, [], fn field, kwlist ->
+            fval = Map.fetch!(item, field)
+            [{:"#{field}_md", TextileMarkdownRenderer.render_one(%{body: fval})} | kwlist]
+          end)
+
+          (mod
+          |> where(id: ^item.id)
+          |> Repo.update_all(set: updates))
+
+          IO.write("\r#{mod}\t#{item.id}\t")
+        end)
+      end)
+
+      IO.puts("")
+    end)
+  end
+end