rails + MySQL 存储emoji表情

database.yml 加入

  charset: utf8mb4
  encoding: utf8mb4
  collation: utf8mb4_unicode_ci

　　创建migration ，更改要存放表情的数据表

    execute "ALTER TABLE table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;"

　　如果该字段是string类型 要加入这一行

    execute "ALTER TABLE table_name CHANGE table_field VARCHAR(191) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci"