What is enum?
enum is data structure more simpley and readable also is a useful method can help us do more things than you thinks.
enum :status {open: 0, close: 1, unknow: -1}
We can see status maybe open, close,unknow more readable for 0,1,-1 isn't it?
Use enum elegantly
On Rails use enum to defined select tag options is more simpley
# activity.rb
class Activity < ActiveRecordBase
enum :status {open: 0, close: 1, unknow: -1}
end
# zh-CN.yml
zh-CN:
active_records:
enums:
activity:
open: 开启
close: 关闭
unknow: 未知
# en.yml
zh-CN:
active_records:
enums:
activity:
open: Opened
close: Closed
unknow: Unknown
# activities/_form.html.erb
<= f.select :status, Activity.status_options, {}, class:'form-control' %>
All is done you just defined i18n for activity form add select tag to dom with options [open,close,unknow] The output
# The result
<select class='form-control'>
<option value='open'>开启</option>
<option value='close'>关闭</option>
<option value='unknow'>未知</option>
</select>
It's too simple and elegantly
More useful API
# get enum value 0,1,-1, here status is open, close or unknow
Activity.statuses[status] #=> 0,1,-1
# opend?, close?, unknow?
activity = Activity.find(1)
activity.opend? #=> true | false
activity.close? #=> true | false
# open!
activity = Activity.find(1)
activity.open! #=> activity.update!(status: 0)
activity.close! #=> activity.update!(status: 1)
# with scopes
class Activity < ActiveRecordBase
scope :open, ->{where(status: 0)}
scope :close, ->{where(status: 1)}
scope :unknow, ->{where(status: -1)}
end
Activity.open # where status = 0
# with not scope
class Activity < ActiveRecordBase
scope :not_open, ->{where.not(status: 0)}
scope :not_close, ->{where.not(status: 1)}
scope :not_unknow, ->{where.not(status: -1)}
end
Activity.not_open # where status != 0
Hope it can help you :)
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