Mysql 如何查询rails方式？轨道3.2

模型之间的关系列表：

class ErrorScope  < ActiveRecord::Base
  belongs_to :server
  has_many :scope_to_fixflow_map
  attr_accessible :id, :server_id, :error_codes, :scoping_method, :priority, :error_codes_is_wildcard_match
  serialize :error_codes
  .....
end

class ScopeToFixflowMap < ActiveRecord::Base
  belongs_to :error_scope
  attr_accessible :id, :server_id, :error_scope_id, :path, :fixflow_class_name
  ......
end

class Server < ActiveRecord::Base
  has_many :error_scopes 
  ......
end

现在我有了一个sql查询，它为我提供了所需的输出：

SELECT fixflow_class_name 
FROM error_scopes s
join scope_to_fixflow_maps m on s.id=m.error_scope_id
join servers serv on serv.id=s.server_id
where error_codes regexp 'error_scope_test'
and path = 'x'
and assettag = 'y'

到目前为止我都试过了。它起作用了

ErrorScope.where("error_codes like ?", "%error_scope_test\n%").select {|tag| tag.server.assettag == "y"}[0].scope_to_fixflow_map.select {|y| y.path == "x"}[0].fixflow_class_name

使用连接

ErrorScope.joins(:server, :scope_to_fixflow_map).where("error_codes LIKE ?", "%error_scope_test%").select {|tag| tag.server.assettag == "y"}[0].scope_to_fixflow_map.select {|y| y.path == "x"}[0].fixflow_class_name

---

我相信一定有更好的方法来做这个查询

不是轨道，而是又快又脏：

ActiveRecord::Base.execute("SELECT fixflow_class_name 
FROM error_scopes s
join scope_to_fixflow_maps m on s.id=m.error_scope_id
join servers serv on serv.id=s.server_id
where error_codes regexp 'error_scope_test'
and path = 'x'
and assettag = 'y'")

返回可以使用的哈希数组，如下所示：

ErrorScope.joins(:server, :scope_to_fixflow_map)
.where("error_codes LIKE ?", "%error_scope_test%") 
.where("servers.assettag='y'")
.where("scope_to_fixflow_maps.path='x'")
.select("scope_to_fixflow_maps.fixflow_class_name")

---

从SQL中不清楚您引用的各个列在哪些表上。ErrorScope.joins:server，：scope\u to\u fixflow\u map.whereerror\u代码如？，%error\u scope\u test%这很好。当我与此链接时，whereserver.assettag='y'会给我错误信息。ActiveRecord:：StatementInvalid:Mysql2:：Error:where子句中的未知列“server.assettag”：@Kavincat Yeah，应该是服务器和范围到固定流的映射，而不是服务器和范围到固定流的映射。更新了答案。

ErrorScope.joins(:server, :scope_to_fixflow_map)
.where("error_codes LIKE ?", "%error_scope_test%") 
.where("servers.assettag='y'")
.where("scope_to_fixflow_maps.path='x'")
.select("scope_to_fixflow_maps.fixflow_class_name")