Ruby on Rails – 表情符号未保存在MySQL中

我正在开发一个Rails应用程序,用户可以将照片上传到他们的个人资料中.每张照片都有一个标题,应该支持表情符号.尽管将表的编码更改为utf8mb4并修改 database.yml,但当我尝试在其标题中保存带有表情符号的照片时,MySQL会返回错误“错误的字符串值”.

该应用程序正在使用Ruby 2.3.0的Rails 5.0.0.1,MySQL正在使用5.7.16版本.

迁移文件：

class CreateUserPhotos < ActiveRecord::Migration[5.0]
  def change
    create_table :user_photos do |t|
      t.string  :title
      t.string  :filename,null: false
      t.integer :visibility,null: false,default: 0
      t.belongs_to :user,foreign_key: true,index: true

      t.timestamps
    end

    reversible do |dir|
      dir.up do
        execute "ALTER TABLE `user_photos` CHANGE `title` `title` VARCHAR(191) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;"
      end

      dir.down do
        execute "ALTER TABLE `user_photos` CHANGE `title` `title` VARCHAR(255) CHARACTER SET utf8 COLLATE utf8_general_ci;"
      end
    end
  end
end

database.yml文件：

production:
  adapter: mysql2
  encoding: utf8mb4
  reconnect: false
  database: app_db
  pool: 5
  username: app_user
  password: app_password
  host: localhost
  socket: /var/run/mysqld/mysqld.sock
  collation: utf8mb4_unicode_ci

ALTER TABLE user_photos CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_bin