ruby 方法(2)

exclude和include

exclude：排除特定对象

include ：包含特定对象

 

inject

[1,2,3].inject(0) {|memo, obj| memo + obj}

[1,2,3].inject(0, &:+)

map

a = ['bob', 'bill']

a.map(&:capitalize)

=> ["Bob", "Bill"]

tap and try

tap

%w(x y z).push('a').shift.tap {|x| p x }.upcase.next

[].tap {|i| i << "abc"}
''.tap {|i| i << do_some_thing }

try

@person.try(:name)
@person.try { |p| "#{p.first_name} #{p.last_name}" }

返回调用函数的时候是否有block参数传人：block_given?

查看数组最后一项是不是Hash：extract_options!

def my_method(*args)
  options = args.extract_options!
  puts "Arguments:  #{args.inspect}"
  puts "Options:    #{options.inspect}"
end

my_method(1, 2)
# Arguments:  [1, 2]
# Options:    {}

my_method(1, 2, :a => :b)
# Arguments:  [1, 2]
# Options:    {:a=>:b}

跳过modle更新数据库：

ActiveRecord::Base.connection.execute("update corps set followers_count = #{followers_count} and staffers_count = #{staffers_count} where id = 1")

attributes对象：

c = Corp.last

c.send(:attributes=, {is_company_page: false, alias_id: c1.id })

获取ActiveRecord::Base中的字段值：

ap Corp   

class Corp < ActiveRecord::Base {

                          :id => :integer,

                        :name => :string,

}