如何使用正则表达式获取架构版本？

Question

我有以下文字：

# encoding: UTF-8
# This file is auto-generated from the current state of the database. Instead
# of editing this file, please use the migrations feature of Active Record to
# incrementally modify your database, and then regenerate this schema definition.
#
# Note that this schema.rb definition is the authoritative source for your
# database schema. If you need to create the application database on another
# system, you should be using db:schema:load, not running all the migrations
# from scratch. The latter is a flawed and unsustainable approach (the more migrations
# you'll amass, the slower it'll run and the greater likelihood for issues).
#
# It's strongly recommended that you check this file into your version control system.

ActiveRecord::Schema.define(version: 20160405090205) do

  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"

我需要 20160405090205 号码。我怎么能得到它？

我已尝试/version.*[0-9]/，但仅捕获版本：20160405090205 。

Answer 1

你可以把它变成一个捕获组

string = "ActiveRecord::Schema.define(version: 20160405090205) do"
version = string.match(/version: (\d+)/m).captures.first

Answer 2

schema = File.read(Rails.root.join('db', 'schema.rb'))
version, *_ = schema.match(/version: (\d+)/m).captures
version # => "20160405090205"

此处需要

version, *_ = ...，因为即使只有一次捕获，captures也会返回一个数组。