how-to-use-rake-tasks-to-generate-migration-sql

Rakefile文件里有load_tasks的方法

http://api.rubyonrails.org/

Load Rake, railties tasks and invoke the registered hooks. Check Rails::Railtie.rake_tasks for more info.Source: hide | on GitHub# File railties/lib/rails/engine.rb, line 451 def load_tasks(app=self)require "rake"run_tasks_blocks(app)self end

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rake_tasks(&block) If you try to define a set of rake tasks on the instance,
these will get passed up to the rake tasks defined on the application's class. Source: hide | on GitHub# File railties/lib/rails/application.rb, line 270 def rake_tasks(&block)self.class.rake_tasks(&block) end

相關文檔

http://guides.rubyonrails.org/command_line.html

https://github.com/ruby/rake

http://eewang.github.io/blog/2013/07/29/how-to-use-rake-tasks-to-generate-migration-sql/

開始寫代碼了。

在lib/tasks/文件夾新建migrate.rake

# 根據下面的博客做了一點點修改 # http://eewang.github.io/blog/2013/07/29/how-to-use-rake-tasks-to-generate-migration-sql/ namespace :db do [ :migrate, :rollback ].each do |n|namespace n do |migration_task| # original_task = migration_task.instance_variable_get("@scope").join ":" [:with_sql, :to_sql ].each do |t|desc "Run migration, and generated SQL" if t == :with_sqldesc "Generate migration SQL" if t == :to_sqltask t => :environment do |sql_task| original_task = sql_task.name.sub(":#{t}", '')case original_task when 'db:migrate' filename = 'upgrade.sql' when 'db:rollback' filename = 'rollback.sql' else raise "unkown migration type #{original_task}"end ActiveRecord::Base.connection.class.class_eval do# alias the adapter's execute for later usealias :old_execute :execute

SQL_FILENAME = filename RUN_SQL = sql_task.name.ends_with?("with_sql")# define our own execute def execute(sql, name = nil) # check for some DDL and DML statementsif /^(create|alter|drop|insert|delete|update)/i.match sqlFile.open(SQL_FILENAME, 'a') { |f| f.puts "#{sql};\n" } old_execute sql, name if RUN_SQLelse# pass everything else to the aliased execute old_execute sql, nameendendend# create or delete content of migration.sqlFile.open(SQL_FILENAME, 'w') { |f| f.puts "-- Script created @ #{Time.now}" }# invoke the normal migration procedure now Rake::Task[original_task].invokeputs "Ran #{original_task} and wrote sql to #{filename}"endendendend end

這時候來執行$ rake -T db

可以看到新增的功能

rake db:create # Creates the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:create:all t... rake db:drop # Drops the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:drop:all to dr... rake db:fixtures:load # Load fixtures into the current environment's database rake db:migrate # Migrate the database (options: VERSION=x, VERBOSE=false, SCOPE=blog) rake db:migrate:status # Display status of migrations rake db:migrate:to_sql # Generate migration SQL rake db:migrate:with_sql # Run migration, and generated SQL rake db:rollback # Rolls the schema back to the previous version (specify steps w/ STEP=n) rake db:rollback:to_sql # Generate migration SQL rake db:rollback:with_sql # Run migration, and generated SQL

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$ mysqldump -uroot -p ott_remote_cms_development > back.sql

$ rake db:drop

$ rake db:create

$ rake db:migrate:with_sql

$ mysql -uroot -p ott_remote_cms_development < back.sql

$ cat upgrade.sql

把sql發給dba就可以了，確實太麻煩了。

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轉載于:https://www.cnblogs.com/iwangzheng/p/5333474.html

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