add option to model

db/migrate/20210706020256_create_users.rb

@@ -2,17 +2,19 @@ class CreateUsers < ActiveRecord::Migration[6.1]
   def change
     create_table :users do |t|
       t.string :name
-      t.string :email
+      t.string :email, null: false
       t.string :password_digest
       t.string :remember_digest
-      t.boolean :admin
+      t.boolean :admin, default: false
       t.string :activation_digest
-      t.boolean :activated
+      t.boolean :activated, default: false
       t.datetime :activated_at
       t.string :password_reset_digest
       t.datetime :password_reset_sent_at
 
       t.timestamps
     end
+    add_index :users, :email, unique: true
+    add_index :user, :password_reset_digest, unique: true
   end
 end