模型保存方法导致异常“没有这样的列”列名为空

Question

我使用find_by_id检索Post实例，在其上设置分数并调用保存。我看到的是一个非常奇怪的错误，其中SQL缺少WHERE子句中的字段。这里是我的铁轨控制台输出：

me> rails c 
Loading development environment (Rails 3.2.22.2) 
2.1.5 :001 > post = Post.find_by_id 123456 
    Post Load (0.1ms) SELECT "posts".* FROM "posts" WHERE "posts"."id" = 123456 LIMIT 1 
=> #<Post id: 123456, url: "http://www.example.com", title: "Test Title", score: nil> 
2.1.5 :002 > post.score = 1 
=> 1 
2.1.5 :003 > post.save 
    (0.1ms) begin transaction 
    (0.2ms) UPDATE "posts" SET "score" = 1 WHERE "posts"."" = 123456 
    (0.0ms) rollback transaction 
ActiveRecord::StatementInvalid: SQLite3::SQLException: no such column: posts.: UPDATE "posts" SET "score" = 1 WHERE "posts"."" = 123456 

Answer 1

的问题是，我的架构定义posts为

create_table "posts", :id => false, :force => true do |t| 
    t.integer "id",  :limit => 8 
    ... 

这意味着Rails的奉命没有主键列。我所要做的只是添加

set_primary_key :id 

到我的模型。