Rails使用环境变量
Many applications require configuration of settings such as email account credentials or API keys for external services. You can pass local configuration settings to an application using environment variables.
Gmail Example
Consider an application that uses Gmail to send email messages. Access to Gmail requires a username and password for access to your Gmail account. In your Rails application, you will need to configure these credentials in the file config/environments/production.rb. A portion of the file might look like this:
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config.action_mailer.smtp_settings = {
address: "smtp.gmail.com",
port: 587,
domain: "example.com",
authentication: "plain",
enable_starttls_auto: true,
user_name: ENV["GMAIL_USERNAME"],
password: ENV["GMAIL_PASSWORD"]
}
You could “hardcode” your Gmail username and password into the file but that would expose it to everyone who has access to your git repository. Instead use the Ruby variable ENV["GMAIL_USERNAME"] to obtain an environment variable. The variable can be used anywhere in a Rails application. Ruby will replace ENV[“GMAIL_USERNAME”] with an environment variable.
Let’s consider how to set local environment variables.
Ruby提取切片
You can get the result you want using collect! or map! to modify the array in-place:
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# 1. collect
x = %w(hello there world)
x.collect! { |element|
(element == "hello") ? "hi" : element
}
puts x
# 2. map
x = %w(hello there world)
x.map! { |element|
if(element == "hello")
"hi" # change "hello" to "hi"
else
element
end
}
puts x # output: [hi there world]
At each iteration, the element is replaced into the array by the value returned by the block.