method

none

v5.0.0.1 - Show latest stable - 0 notes - Class: ActiveRecord::QueryMethods

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What's this?

none() public

Returns a chainable relation with zero records.

The returned relation implements the Null Object pattern. It is an object with defined null behavior and always returns an empty array of records without querying the database.

Any subsequent condition chained to the returned relation will continue generating an empty relation and will not fire any query to the database.

Used in cases where a method or scope could return zero records but the result needs to be chainable.

For example:

@posts = current_user.visible_posts.where(name: params[:name])
# the visible_posts method is expected to return a chainable Relation

def visible_posts
  case role
  when 'Country Manager'
    Post.where(country: country)
  when 'Reviewer'
    Post.published
  when 'Bad User'
    Post.none # It can't be chained if [] is returned.
  end
end

Show source

# File activerecord/lib/active_record/relation/query_methods.rb, line 782
    def none
      where("1=0").extending!(NullRelation)
    end

none

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