mysql - Ruby 模型将 Controller 值存储在 MYSQL 中并添加字符

Question

我有一个如下所示的 Controller 方法。但是，schedule = params[:message][:schedule] 接受这样的输入 ["","2"] 并作为字符串存储在数据库中那就是MySQL。

当Schedule.create(execution_time:scheduled_time，lists:“lists”，message_id:@message.id，user_id:current_user.id)时，存储的值为数据库是“- --\n-\"58\"\n-\"\"\n" 以及当 Schedule.create(execution_time: Scheduled_time,lists: "#{lists}", message_id: @message .id, user_id: current_user.id) 那么存储的值是这样的 "[\"34\",\"\"]" 但所需的值是 [ “34”，“”]。

Controller 方法如下；

def create
  @lists = current_user.lists.all
  @message = Message.new(params[:message])
  lists = params[:message][:lists]
  schedule = params[:message][:schedule]

  if @message.save
    if schedule.blank?
      MessageWorker.perform_async(@message.id, lists, current_user.id)
    else
      scheduled_time = DateTime.strptime(schedule,"%m/%d/%Y %H:%M %p %z").to_datetime.utc.strftime("%Y-%m-%d %H:%M:%S")
      Schedule.create(execution_time: scheduled_time, lists: "#{lists}", message_id: @message.id, user_id: current_user.id)
    end
    redirect_to new_message_path, notice: 'Message was successfully added to the queue.'

  else
    render action: "new"
    flash[:notice] = "Messages Not Sent"
end

为什么存储的值中要加斜杠？ 预先感谢您。

Answer 1

添加斜杠是为了转义引号字符。当获取数组并将其设为字符串时，这是正常的，这是幕后发生的事情。请参阅this Wikipedia article有关转义字符的更多信息。

如果您确实想在一个字段中存储多个值(考虑存储在单独的表中，然后可以进行JOIN连接)，那么可以将它们存储为 JSON 格式，或者存储为逗号分隔值。这两种方法都要求您在从数据库中读取存储的值时对其进行解析。

JSON:

lists = JSON.generate(params[:message][:lists]) # an array such as ["1", "2"], converted to JSON format
=> "[\"1\",\"2\"]" # it's a string, with quotes escapted. Store this in the database.

# then you can parse it to make it an array again
JSON.parse(lists)
=> ["1", "2"]

逗号分隔值:

lists = params[:message][:lists].join(",") # assuming params[:message][:lists] is an array
=> "1,2" # A string with each value from the array separated by a comma. Store this in database

# then when you read that value from database
lists.split(",")
=> ["1", "2"] # back in array format

您正在获取一个数组，然后将其存储为字符串。转换为此格式时，需要斜杠。要将字符串恢复为数组格式，您需要解析字符串 - 这将“删除”斜杠。确保您了解 ["1", "2"] 和 "[\"1\",\"2\"]"

之间的区别