Moved species from Pokémon to revision

The migration will set all of the revisions of each Pokémon to have the species that that Pokémon was set to. If reversed, the migration sets the Pokémon's species to the first revision's species, which mimics the behavior of the engine from before this change, but do note that running the migration backwards like this can lose data.

This change slightly affects the loading time of the front page. See #2.

refs #3

1 files changed, 39 insertions, 0 deletions

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+class MoveSpeciesToRevision < ActiveRecord::Migration[5.1]
+  def up
+    change_table :pokeviewer_revisions do |t|
+      t.references :species, null: true
+    end
+
+    Pokeviewer::Revision.all.each do |r|
+      r.species_id = r.pokemon.species_id
+      r.save!
+    end
+
+    remove_column :pokeviewer_pokemon, :species_id
+
+    change_column_null :pokeviewer_revisions, :species_id, false
+
+    add_foreign_key :pokeviewer_revisions, :pokeviewer_species,
+      column: :species_id
+  end
+
+  def down
+    def up
+      change_table :pokeviewer_pokemon do |t|
+        t.references :species, null: true
+      end
+
+      Pokeviewer::Pokemon.all.each do |p|
+        p.species_id = p.revisions.first.species_id
+        p.save!
+      end
+
+      remove_column :pokeviewer_revisions, :species_id
+
+      change_column_null :pokeviewer_pokemon, :species_id, false
+
+      add_foreign_key :pokeviewer_pokemon, :pokeviewer_species,
+        column: :species_id
+    end
+  end
+end