Question

我在我的Raspberry Pi上使用Postgresql 9.1运行了一个应用程序。

我的第一次迭代是将天气记录添加到名为＆＃34; Weathers＆＃34;的表中。那是成功的。

我的下一次迭代是使用psychopg2将来自Python的记录写入另一个名为＆＃34; weather＆＃34;的表中。这也是成功的。

应该成功的是将我的应用中的Weather类更改为新字段。但DataMapper返回映射错误：

@records = Weather.all(:order => :timestamp.desc)
ArgumentError at /
+options [:order]+ entry :timestamp does not map to a property in Weather

重新阅读datamapper.org文档表明它与我的表名有关，所以我迁移过旧的＆＃34;天气＆＃34;把桌子变成了另一个名为“＃34; old＆＃34;并且放弃了＃34;天气＆＃34;表。但是DataMapper仍然无法找到这个表。

我的Postgres环境以及目标表的截断视图是：

            List of relations
 Schema |   Name    | Type  | Owner 
--------+-----------+-------+-------
 public | customers | table | pi
 public | older     | table | pi
 public | systemlog | table | pi
 public | weather   | table | pi
(4 rows)

                                                         Table "public.weather"
           Column            |            Type             |                      Modifiers                       | Storage  | Description 
-----------------------------+-----------------------------+------------------------------------------------------+----------+-------------
 id                          | integer                     | not null default nextval('weather_id_seq'::regclass) | plain    | 
 timestamp                   | timestamp without time zone | default now()                                        | plain    | 
 currentwindspeed            | real                        |                                                      | plain    | 
 bmp180temperature           | integer                     |                                                      | plain    | 
Indexes:
    "weather_pkey" PRIMARY KEY, btree (id)
Has OIDs: no

我的Datamapper类是：

class Weather
  include DataMapper::Resource
  property :id,  Serial
  property :bmp180temperature, String
  property :insidehumidity, String
  property :totalrain, String
  property :currentwinddirection, String
  property :currentWindSpeed, String
  property :timestamp, DateTime
end
DataMapper.finalize
Weather.auto_upgrade!

由于这是Ruby我激发了IRb，需要Datamapper gem并得到：

records = Weather.all
DataObjects::SyntaxError: ERROR:  column "bmp180temperature" does not exist
LINE 1: SELECT "id", "bmp180temperature", "insidehumidity", "totalra...
                     ^
 (code: 50360452, sql state: 42703, query: SELECT "id", "bmp180temperature", "insidehumidity", "totalrain", "currentwinddirection", "current_wind_speed", "timestamp" FROM "weathers" ORDER BY "id", uri: postgres:pi@localhost/postgres?scheme=postgres&user=pi&password=pw&host=localhost&port=&path=/postgres&query=&fragment=&adapter=postgres)
        from /var/lib/gems/1.9.1/gems/dm-do-adapter-1.2.0/lib/dm-do-adapter/adapter.rb:147:in `execute_reader'
        from /var/lib/gems/1.9.1/gems/dm-do-adapter-1.2.0/lib/dm-do-adapter/adapter.rb:147:in `block in read'
        from /var/lib/gems/1.9.1/gems/dm-do-adapter-1.2.0/lib/dm-do-adapter/adapter.rb:276:in `with_connection'

这让我觉得它找不到合适的桌子。或许可以使用id列。

我在CodeIgniter框架中看到似乎是用于PHP的DataMapper，但我不确定它是否与我在Ruby中使用的DataMapper相同。

为了让DataMapper找到这张表，我忽略了什么？

Datamapper无法找到表

0 个答案: