Ruby on rails Mongoid:：Criteria.only（：name）返回除name以外的所有字段nil

当我运行

User.only（：name）.all

或该查询的任何变体时，我得到：

[#<User _id: 52003fb8487874985b
000003, created_at: nil, updated_at: nil, role_ids: nil, name: "Tom Amfeagfhbdge Bowersman", usernam
e: nil, fb_id: nil, fb_token: nil, email: nil, encrypted_password: nil, reset_password_token: nil, r
eset_password_sent_at: nil, remember_created_at: nil, sign_in_count: nil, current_sign_in_at: nil, l
ast_sign_in_at: nil, current_sign_in_ip: nil, last_sign_in_ip: nil>,  
 #<User _id: 5200405a487874fb550
00004, created_at: nil, updated_at: nil, role_ids: nil, name: "Carol Amfdheibbjbf Sadanwitz", userna
me: nil, fb_id: nil, fb_token: nil, email: nil, encrypted_password: nil, reset_password_token: nil,
reset_password_sent_at: nil, remember_created_at: nil, sign_in_count: nil, current_sign_in_at: nil,
last_sign_in_at: nil, current_sign_in_ip: nil, last_sign_in_ip: nil>,  
 #<User _id: 520040d14878746fe5
000005, created_at: nil, updated_at: nil, role_ids: nil, name: "Tom Amfdidheeidd Yangson", username:
 nil, fb_id: nil, fb_token: nil, email: nil, encrypted_password: nil, reset_password_token: nil, res
et_password_sent_at: nil, remember_created_at: nil, sign_in_count: nil, current_sign_in_at: nil, las
t_sign_in_at: nil, current_sign_in_ip: nil, last_sign_in_ip: nil>]

---

您可以这样做，而不是“id”、“name”

---

{data:User.only（：name）.all.map（&:attributes）}

到目前为止，我找到的唯一方法是直接使用Mongo驱动程序

Mongo:：MongoClient.new（ENV['MONGOID\u HOST']，ENV['MONGOID\u PORT']）.db（ENV['MONGOID\u DATABASE']）。collection（'friends'）。find（{}，{fb\u id:1}）

"data": [
  {
    "id": "5008484"
  },
  {
    "id": "47402727"
  },
  {
    "id": "500154435"
  },
  {
    "id": "500598450"
  },
  {
    "id": "500655911"
  },
  {
    "id": "500666528"
  },
  {
    "id": "500700148"
  },
  {
    "id": "500973616"
  },
  {
    "id": "501130485"
  },
  {
    "id": "501254060"
  }]