Ruby on Rails：空值的訂單記錄

User.where(id: users_ids) 
    .joins('LEFT JOIN names ON names.user_id = users.id AND names.primary = 1') 
    .joins('LEFT JOIN emails ON emails.user_id = users.id AND emails.primary = 1') 
    .select('users.*, names.first_name AS f_name , emails.email AS primary_email')

我需要訂購記錄f_name。當f_name爲nil時，記錄將移至最後並通過電子郵件進行排序。Ruby on Rails：空值的訂單記錄

下面是查詢，

User.where(id: users_ids) 
    .joins('LEFT JOIN names ON names.user_id = users.id AND names.primary = 1') 
    .joins('LEFT JOIN emails ON emails.user_id = users.id AND emails.primary = 1') 
    .select('users.*, names.first_name AS f_name , emails.email AS primary_email') 
    .where('names.first_name IS NOT NULL') 
    .order('f_name asc').union(
User.where(id: users_ids) 
    .joins('LEFT JOIN names ON names.user_id = users.id AND names.primary = 1') 
    .joins('LEFT JOIN emails ON emails.user_id = users.id AND emails.primary = 1') 
    .select('users.*, names.first_name AS f_name , emails.email AS primary_email') 
    .where('names.first_name IS NULL') 
    .order('primary_email asc'))

上面的查詢不起作用。

數據庫 - MySQL的

來源

2016-11-27 Sergii Naumenko

它是如何不工作？ –

對不起，我忘了添加我正在使用分頁'.paginate（page：params [：page]）。per_page（10）'並且錯誤'undefined method'paginate'for＃' –

不知道Arel :: Nodes :: Union或paginate方法來自何處。可能不是'.union'，請嘗試使用'||'或'.or'（如果您使用的是Rails 5） –

我解決不良方式這個問題，但解決

users_with_names = User.where(id: users_ids) 
         .joins('LEFT JOIN names ON names.user_id = users.id AND names.primary = 1') 
         .joins('LEFT JOIN emails ON emails.user_id = users.id AND emails.primary = 1') 
         .select('users.*, names.first_name AS f_name , emails.email AS user_email') 
         .where('names.first_name IS NOT NULL') 
         .order('f_name asc') 

users_without_names = User.where(id: users_ids) 
          .joins('LEFT JOIN names ON names.user_id = users.id AND names.primary = 1') 
          .joins('LEFT JOIN emails ON emails.user_id = users.id AND emails.primary = 1') 
          .select('users.*, names.first_name AS f_name , emails.email AS user_email') 
          .where('names.first_name IS NULL') 
          .order('user_email asc') 

@contacts = [users_with_names, users_without_names].flatten.paginate(page: params[:page], per_page: 10)

來源

2016-11-27 11:35:08

這個問題是這樣解決的

joins('LEFT JOIN names ON names.user_id = users.id AND names.primary = 1') 
.joins('LEFT JOIN emails ON emails.user_id = users.id AND emails.primary = 1') 
.select('users.*, names.first_name AS f_name , emails.email AS user_email, 
      names.last_name AS l_name, names.middle_name AS m_name, ISNULL(names.first_name) AS name_present') 
.order('name_present, f_name ASC, emails.email ASC') 
.group('users.id')

來源

2016-11-28 20:43:24

Ruby on Rails：空值的訂單記錄

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