统计协会

Question

我是RoR新手，我需要一些关联方面的帮助。我使用的是rails 6.0.3.4和ruby2.7.0。

用户可以创建案例，案例属于某一地区。地区属于一个州。必须是这样，因为案件不属于一个国家。

现在我想给出每个州的特定诊断的病例数。我得用地区来为一个州弄到所有的案子。我该如何建造这个地方(.)情况如何？

<!-- State -->
    <div class="card">
      <div class="card-body">
        <h5 class="card-title">State</h5>
        <p><%= State.find(1).titel%> (<%= @diagnosis.cases.where(...).count %>)</p>
      </div>
    </div>

我的模特

case.rb

class Case < ApplicationRecord
  before_create :set_pseud
  belongs_to :user
  belongs_to :diagnosis
  belongs_to :district
  belongs_to :report, optional: true
end

district.rb

class District < ApplicationRecord
  has_many :users
  has_many :cases
  has_many :reports
  belongs_to :state
end

state.rb

class State < ApplicationRecord
  has_many :districts
  has_many :users
end

以更好地理解我的schema.rb

ActiveRecord::Schema.define(version: 2021_02_11_140244) do

  create_table "cases", options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci", force: :cascade do |t|
    t.string "first_name"
    t.string "last_name"
    t.string "gender"
    t.date "birthdate"
    t.string "place_of_residence"
    t.string "diagnosis"
    t.bigint "user_id"
    t.datetime "confirmed_at"
    t.datetime "created_at", precision: 6
    t.datetime "updated_at", precision: 6, null: false
    t.bigint "diagnosis_id"
    t.bigint "district_id"
    t.bigint "report_id"
    t.string "pseud"
    t.index ["diagnosis_id"], name: "index_cases_on_diagnosis_id"
    t.index ["district_id"], name: "index_cases_on_district_id"
    t.index ["pseud"], name: "index_cases_on_pseud"
    t.index ["report_id"], name: "index_cases_on_report_id"
    t.index ["user_id"], name: "index_cases_on_user_id"
  end

  create_table "diagnoses", options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci", force: :cascade do |t|
    t.string "illness"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
  end

  create_table "districts", options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci", force: :cascade do |t|
    t.string "name"
    t.string "place"
    t.integer "postal_code"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.bigint "state_id", null: false
    t.index ["state_id"], name: "index_districts_on_state_id"
  end

  create_table "reports", options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci", force: :cascade do |t|
    t.bigint "district_id"
    t.text "comment"
    t.datetime "date"
    t.bigint "user_id"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.index ["district_id"], name: "index_reports_on_district_id"
    t.index ["user_id"], name: "index_reports_on_user_id"
  end

  create_table "states", options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci", force: :cascade do |t|
    t.string "titel"
    t.string "abbr"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
  end

  create_table "users", options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci", force: :cascade do |t|
    t.string "email", default: "", null: false
    t.string "encrypted_password", default: "", null: false
    t.string "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.integer "role"
    t.string "first_name"
    t.string "last_name"
    t.bigint "district_id"
    t.bigint "state_id"
    t.index ["district_id"], name: "index_users_on_district_id"
    t.index ["email"], name: "index_users_on_email", unique: true
    t.index ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true
    t.index ["state_id"], name: "index_users_on_state_id"
  end

end

Answer 1

您应该在状态中添加一个进一步的关联：

has_many :cases, through: :districts

与其在视图中查找状态，不如在控制器中这样做，并将其传递给实例变量中的视图：

@state = State.find(params[:id])

我假设您在这里使用的是显示操作，而不是出于某种原因手动编写状态ID。

然后你可以这样做：

@state.cases.where(diagnoses: { id: @diagnosis.id }).count

或者，如果您愿意的话，可以跳过@diagnosis上的.id：

@state.cases.where(diagnoses: { id: @diagnosis }).count