在关联模型上使用 Ruby on Rails 4 中的命名范围

Question

我的应用由 3 个模型组成：

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

架构大致如下：

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

我正在尝试根据输入过滤掉数据。例如，有人搜索身高 5'8"、黑色眼睛和棕色头发的模型，我应该通过查询数据库只显示这些模型。

因此，我尝试在模型中使用命名范围。我不确定如何通过在FashionModel 模型中编写范围来确定measurement 表的属性范围。

我在网上阅读了一些资源，据我了解，我写了类似

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

虽然我不想将Amber 硬编码到 eye 字段中，但在尝试访问此范围时，我的控制台中出现错误。我做类似的事情

a = FashionModel.all
a.eye_color

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

我也试过这样做

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

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

所以基本上我想从父模型扩展到子模型。 任何帮助深表感谢！谢谢

Answer 1

将您的范围定义为：

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

然后使用如下参数查询：

FashionModel.eye_color("Amber")