rails-rake-task-使用.md

How to Write a Rake Task

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desc "Print reminder about eating more fruit."

task :apple do
  puts "Eat more apples!"
end

using Rails, you can save this under lib/tasks/apple.rake.

To run this task:

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rake apple
# "Eat more apples!"

rake task 开发

*.rake 中除了可以使用ruby，还可以调用其他ruby、sh。

you can copy files with cp, create directories with mkdir_p, and even change file permissions with chown.

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task :clean_cache do
  rm_r FileList["tmp/cache/*"]
end

注意，rm_r 可以直接不用确认就删除文件。

调用其他 rb 程序

running a Ruby script inside the data folder in my Rails project.

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task :import do
  puts "Importing data..."
  Dir.chdir(Rails.root.join("data")) { ruby "load-data.rb" }
end

给 task 限定 namespace

例如， 在 backup namespace 中定义 create、list

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namespace :backup do
  task :create do
    # ...
  end
  task :list do
    # ...
  end
end

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rake backup:create

task 的调用依赖

In this example, load_database will run before create_examples.

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task create_examples: "load_database" do
  # ...
end

调用其他 task

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task :coverage do
  ENV['COVERAGE'] = 'true'
  Rake::Task["test"].execute
end

Use Rake Rules

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task compress: FileList["/tmp/*.txt"].ext(".txt.gz")
rule '.txt.gz' => '.txt' do |t|
  sh "gzip", "-k", "-f", t.source
end

  1. We use the FileList class, which is part of Rake, to define a list of files we want to work with.

  2. The rule starts with the TARGET extension, to make the rule match we have to use .ext(".txt.gz") on the FileList.

  3. This .txt.gz => .txt doesn’t mean we go from txt.gz to txt, it’s the other way around. The arrow is hash syntax.

Rake 命令

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rake -T (list available tasks)
rake -P (list tasks & their dependencies)
rake -W (list tasks & where they are defined)
rake -V (verbose mode, echo system commands)
rake -t (debugging mode)
rake -f (use a specific Rakefile)

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> rake -T test
rake test         # Runs all tests in test folder except system ones
rake test:db      # Run tests quickly, but also reset db
rake test:system  # Run system tests only