Merge branch 'refactor/db-not-null-constraints-for-users' into 'develop'

Add NOT NULL constraints for users table

See merge request pleroma/pleroma!1910

priv/repo/migrations/20191026191910_set_not_null_for_users.exs

+defmodule Pleroma.Repo.Migrations.SetNotNullForUsers do
+  use Ecto.Migration
+
+  # modify/3 function will require index recreation, so using execute/1 instead
+
+  def up do
+    # irreversible
+    execute("UPDATE users SET follower_count = 0 WHERE follower_count IS NULL")
+
+    execute("ALTER TABLE users
+    ALTER COLUMN following SET NOT NULL,
+    ALTER COLUMN local SET NOT NULL,
+    ALTER COLUMN source_data SET NOT NULL,
+    ALTER COLUMN note_count SET NOT NULL,
+    ALTER COLUMN follower_count SET NOT NULL,
+    ALTER COLUMN blocks SET NOT NULL,
+    ALTER COLUMN domain_blocks SET NOT NULL,
+    ALTER COLUMN mutes SET NOT NULL,
+    ALTER COLUMN muted_reblogs SET NOT NULL,
+    ALTER COLUMN muted_notifications SET NOT NULL,
+    ALTER COLUMN subscribers SET NOT NULL,
+    ALTER COLUMN pinned_activities SET NOT NULL,
+    ALTER COLUMN emoji SET NOT NULL,
+    ALTER COLUMN fields SET NOT NULL,
+    ALTER COLUMN raw_fields SET NOT NULL")
+  end
+
+  def down do
+    execute("ALTER TABLE users
+    ALTER COLUMN following DROP NOT NULL,
+    ALTER COLUMN local DROP NOT NULL,
+    ALTER COLUMN source_data DROP NOT NULL,
+    ALTER COLUMN note_count DROP NOT NULL,
+    ALTER COLUMN follower_count DROP NOT NULL,
+    ALTER COLUMN blocks DROP NOT NULL,
+    ALTER COLUMN domain_blocks DROP NOT NULL,
+    ALTER COLUMN mutes DROP NOT NULL,
+    ALTER COLUMN muted_reblogs DROP NOT NULL,
+    ALTER COLUMN muted_notifications DROP NOT NULL,
+    ALTER COLUMN subscribers DROP NOT NULL,
+    ALTER COLUMN pinned_activities DROP NOT NULL,
+    ALTER COLUMN emoji DROP NOT NULL,
+    ALTER COLUMN fields DROP NOT NULL,
+    ALTER COLUMN raw_fields DROP NOT NULL")
+  end
+end