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Merge pull request #13198 from chancancode/enum_docs

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Make clear that the enum array should not be changed once defined. [ci skip]
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Godfrey Chan 2013-12-05 18:01:29 -08:00
commit c69ea79994
1 changed files with 12 additions and 1 deletions
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13
activerecord/lib/active_record/enum.rb
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@ -26,12 +26,23 @@ module ActiveRecord
#
# Good practice is to let the first declared status be the default.
#
# Finally, it's also possible to explicitly map the relation between attribute and database integer:
# Finally, it's also possible to explicitly map the relation between attribute and
# database integer with a +Hash+:
#
# class Conversation < ActiveRecord::Base
# enum status: { active: 0, archived: 1 }
# end
#
# Note that when an +Array+ is used, the implicit mapping from the values to database
# integers is derived from the order the values appear in the array. In the example,
# <tt>:active</tt> is mapped to +0+ as it's the first elemet, and <tt>:archived</tt>
# is mapped to +1+. In general, the +i+-th element is mapped to <tt>i-1</tt> in the
# database.
#
# Therefore, once a value is added to the enum array, its position in the array must
# be maintained, and new values should only be added to the end of the array. To
# remove unused values, the explicit +Hash+ syntax should be used.
#
# In rare circumstances you might need to access the mapping directly.
# The mappings are exposed through a constant with the attributes name:
#