在相关模型上使用RubyonRails 4中的命名作用域

Question

我的应用程序由3种型号组成：

FashionModel
Measurement
ModelProfile

class FashionModel < ActiveRecord::Base
  has_secure_password
  has_one :model_profile
  has_one :measurement
  accepts_nested_attributes_for :model_profile
  accepts_nested_attributes_for :measurement
end

class ModelProfile < ActiveRecord::Base
  belongs_to :fashion_model
end

class Measurement < ActiveRecord::Base
  belongs_to :fashion_model
end

模式大致如下：

create_table "fashion_models", force: :cascade do |t|
    t.string   "first_name",             limit: 25
    t.string   "last_name",              limit: 25
    t.string   "email",                  limit: 255, null: false
    t.datetime "created_at",                         null: false
    t.datetime "updated_at",                         null: false
    t.string   "password_digest",        limit: 255
    t.string   "password_reset_token",   limit: 255
    t.datetime "password_reset_sent_at"
  end
  create_table "measurements", force: :cascade do |t|
    t.integer  "fashion_model_id", limit: 4
    t.decimal  "feet",                         precision: 10
    t.decimal  "inches",                       precision: 10
    t.decimal  "bust",                         precision: 10, default: 36
    t.decimal  "waist",                        precision: 10, default: 28
    t.decimal  "hips",                         precision: 10, default: 36
    t.decimal  "shoes",                        precision: 10
    t.integer  "dress",            limit: 4
    t.string   "eyes",             limit: 255
    t.string   "hair",             limit: 255
    t.datetime "created_at",                                               null: false
    t.datetime "updated_at",                                               null: false
  end
  create_table "model_profiles", force: :cascade do |t|
    t.integer  "fashion_model_id", limit: 4
    t.string   "phone_number",     limit: 255
    t.date     "birthdate"
    t.text     "bio",              limit: 65535
    t.string   "location",         limit: 255,                  default: "Venice"
    t.string   "gender",           limit: 255
    t.decimal  "rate",                           precision: 10, default: 100
    t.string   "profile_picture",  limit: 255
    t.datetime "created_at",                                                       null: false
    t.datetime "updated_at",                                                       null: false
  end
  add_index "model_profiles", ["fashion_model_id"], name: "index_model_profiles_on_fashion_model_id", using: :btree
  add_foreign_key "bookings", "fashion_models"
  add_foreign_key "fashion_model_photos", "fashion_models"
end

我正试图根据输入筛选出数据。例如，有人搜索身高5英尺8英寸、黑眼睛和棕色头发的模特，我应该通过查询数据库只显示这些模特

因此，我尝试在模型中使用命名作用域。我不确定如何通过在FashionModel模型中写入范围来确定measurement表的属性的范围。

我在网上阅读了一些资源，根据我的理解，我写了一些类似的东西

scope :eye_color, includes(:measurement).where(measurement: { eyes: "Amber" })

虽然我不想将Amber硬编码到eyes字段中，但在尝试访问此作用域时，我在控制台中遇到了一个错误。我做一些类似的事情

a = FashionModel.all
a.eye_color

这给了我一个和ArgumentError: wrong number of arguments (given 0, expected 1)。

我也试过做这个

scope :eye_color, -> (eye_color) { where eyes: eye_color }

然后用a.eye_color("Amber")调用它，这反过来又给了我一个NoMethodError: undefined method 'measurement' for Class。

因此，基本上我想从父模型扩展到子模型。非常感谢您的帮助！感谢

Answer 1

将您的范围定义为：

scope :eye_color, ->(eye_color) {
  includes(:measurements).where(measurements: {eyes: eye_color}) 
}

然后使用以下参数进行查询：

FashionModel.eye_color("Amber")