您好我在模型中使用has_and_belongs_to_many。 我想设置各种存在的价值。 并将每个核心的最大种类数设置为3
class Core < ActiveRecord::Base
has_and_belongs_to_many :kinds, :foreign_key => 'core_id', :association_foreign_key => 'kind_id'
end
我该怎么办?
感谢
答案 0 :(得分:6)
validate :require_at_least_one_kind
validate :limit_to_three_kinds
private
def require_at_least_one_kind
if kinds.count == 0
errors.add_to_base "Please select at least one kind"
end
end
def limit_to_three_kinds
if kinds.count > 3
errors.add_to_base "No more than 3 kinds, please"
end
end
答案 1 :(得分:2)
你可以尝试这样的东西(在Rails 2.3.4上测试):
class Core < ActiveRecord::Base
has_and_belongs_to_many :kinds, :foreign_key => 'core_id', :association_foreign_key => 'kind_id'
validate :maximum_three_kinds
validate :minimum_one_kind
def minimum_one_kind
errors.add(:kinds, "must total at least one") if (kinds.length < 1)
end
def maximum_three_kinds
errors.add(:kinds, "must not total more than three") if (kinds.length > 3)
end
end
...以下列方式运作:
require 'test_helper'
class CoreTest < ActiveSupport::TestCase
test "a Core may have kinds" do
core = Core.new
3.times { core.kinds << Kind.new }
assert(core.save)
end
test "a Core may have no more than 3 kinds" do
core = Core.new
4.times { core.kinds << Kind.new }
core.save
assert_equal(1, core.errors.length)
assert_not_nil(core.errors['kinds'])
end
test "a Core must have at least one kind" do
core = Core.new
core.save
assert_equal(1, core.errors.length)
assert_not_nil(core.errors['kinds'])
end
end
显然上面的内容并不是特别干燥或生产就绪,但你明白了。