Ruby-on-rails 如何将时间戳插入到 rails 数据库列中
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How to insert timestamp into rails database-column
提问by zyrup
I just started with RoR and have a question: How can I insert the current timestamp (or any type of time) into the model? Below you see the log function create.
我刚开始使用 RoR 并有一个问题：如何将当前时间戳（或任何类型的时间）插入模型中？下面你会看到日志函数创建。
def create
@log = Log.new(params[:log])
respond_to do |format|
if @log.save
format.html { redirect_to @log, notice: 'Log was successfully created.' }
format.json { render json: @log, status: :created, location: @log }
else
format.html { render action: "new" }
format.json { render json: @log.errors, status: :unprocessable_entity }
end
end
end
回答by Richard Brown
The Rails model generator automatically creates created_atand updated_atdatetimefields in the database for you. These fields are automatically updated when a record is created or updated respectively.
Rails 模型生成器会自动为您在数据库中创建 created_at和updated_atdatetime字段。这些字段分别在创建或更新记录时自动更新。
If you want to manually create a timestamp, add a datetime column (e.g. timestamp_field) to the database and use a before_savecallback in your model.
如果您想手动创建时间戳，请将日期时间列（例如timestamp_field）添加到数据库并before_save在您的模型中使用回调。
class Log < ActiveRecord::Base
before_save :generate_timestamp
def generate_timestamp
self.timestamp_field = DateTime.now
end
end
回答by Leo Correa
Using the rails generator e.g rails generate model Lograils creates two timestamp fields automatically for you.
使用 rails 生成器，例如rails generate model Lograils 会自动为您创建两个时间戳字段。
created_atand updated_atboth of these fields will be filled by Rails when you create a new record doing Log.newthen saveon that record or Log.createThe updated_atfield gets updated only when you update the record's attributes or when you use the method touchon an instance of the model.
created_at而updated_at这两个领域将Rails的，当你创建一个新的记录做填充Log.new，然后save在该记录或Log.create将updated_at只有当你更新记录的属性或当您使用方法字段被更新touch的模型的实例。
Now, if you wanted to create another field with the timestamp type you could make a migration that adds a column to your model like this
现在，如果您想创建另一个具有时间戳类型的字段，您可以进行迁移，将一列添加到您的模型中，如下所示
rails generate migration add_some_timestamp_field_to_logs my_timestamp_field:timestamp
This will generate a migration that will add a column named my_timestamp_fieldwith a timestamptype, just like the created_atand updated_at
这将产生一个迁移，将添加一个名为列my_timestamp_field有timestamp型，就像created_at和updated_at
