我想从我的应用程序中的所有用户那里获取 ID 为 37 的品牌的所有标签。以下内容有效,但仅从应用程序中当前的 2 个用户之一获取标签:
<%= BrandUser.last.brand.tags.join(", ") %>
以下是我的尝试,但不起作用:
<%= BrandUser.where(:brand_id => 37).each {|brand| p brand.tags} %>
- 品牌 has_many 标签、has_many brand_users 和 has_many users 通过 brand_users
- 用户 has_many :brand_users 和 has_many :brands, :through => :brand_users
- BrandUser belongs_to :brand 和 belongs_to :user
以下是我的架构:
ActiveRecord::Schema.define(:version => 20110824083919) do
create_table "brand_users", :force => true do |t|
t.integer "brand_id"
t.integer "user_id"
t.datetime "created_at"
t.datetime "updated_at"
end
create_table "brands", :force => true do |t|
t.string "name"
t.datetime "created_at"
t.datetime "updated_at"
t.string "user_id"
end
create_table "taggings", :force => true do |t|
t.integer "tag_id"
t.integer "taggable_id"
t.string "taggable_type"
t.integer "tagger_id"
t.string "tagger_type"
t.string "context"
t.datetime "created_at"
end
add_index "taggings", ["tag_id"], :name => "index_taggings_on_tag_id"
add_index "taggings", ["taggable_id", "taggable_type", "context"], :name => "index_taggings_on_taggable_id_and_taggable_type_and_context"
create_table "tags", :force => true do |t|
t.string "name"
end
create_table "users", :force => true do |t|
t.string "provider"
t.string "uid"
t.string "name"
t.datetime "created_at"
t.datetime "updated_at"
end
end
解决方案:
根据下面的答案,在控制台中运行以下命令给了我正在寻找的标签:
ActsAsTaggableOn::Tagging.where(:taggable_id => 37, :taggable_type => 'Brand', :tagger_type => 'User').includes(:tag)
但是运行以下命令也可以:
Brand.find(37).all_tags_on(:tags)