Question

我正在尝试了解boss_db模块以访问我在芝加哥老板设置的mongodb

我找到了一个使用Here

中的boss_db访问该数据的示例

示例：

Puppy = boss_db:find("puppy-1"),
io:format("Puppy's name: ~p~n", [Puppy:name()]).

但是当我用我的代码尝试这一切时

Cl= boss_db:find(clientList, [], [{limit,1}]),
io:format("Puppy's name: ~p~n", [Cl:datablock()]),

我收到此错误消息

[{erlang,apply,
     [[{clientList,"clientList-53e30e8b10af5d1503000287",
           <<"Sheet1">>,<<"Jason@email.com.au\n">>,
           <<131,108,0,0,0,3,104,2,107,0,6,70,105,101,108,100,49,
             107,...>>}],
      datablock,[]],
     []},
 {pigeon_greeting_controller,template,3,
     [{file,
          "/home/jason/pigeon/src/controller/pigeon_greeting_controller.erl"},
      {line,57}]},
 {boss_web_controller,call_controller_action,3,
     [{file,"src/boss/boss_web_controller.erl"},{line,363}]},
 {boss_web_controller,apply_action,4,
     [{file,"src/boss/boss_web_controller.erl"},{line,355}]},
 {boss_web_controller,execute_action_inner,9,
     [{file,"src/boss/boss_web_controller.erl"},{line,334}]},
 {boss_web_controller_handle_request,process_dynamic_request,
     4,
     [{file,"src/boss/boss_web_controller_handle_request.erl"},
      {line,242}]},
 {boss_web_controller_handle_request,process_request,4,
     [{file,"src/boss/boss_web_controller_handle_request.erl"},
      {line,228}]},
 {boss_web_controller_handle_request,set_timer,7,
     [{file,"src/boss/boss_web_controller_handle_request.erl"},
      {line,148}]}]

我知道我得到的返回数据是我可以做的

[{clientList, _,_,_, Datablock}] = boss_db:find(clientList, [], [{limit,1}]),
io:format("data block is : ~p~n", [Datablock]).

它没有问题就回来了

我的偏好是通过字段名称找到它而不是模式匹配，因为模式可能会在某些时候发生变化。

我正在查看旧示例，或者这个示例仅适用于关系数据库。我找不到有关如何执行此操作的简单示例的网站

Answer 1

您引用的代码使用boss_db：find / 1返回记录。您的代码使用Boss_db：find / 3返回记录列表。

上面的示例，使用我的数据库，重现了问题

1> CL = boss_db:find(customer, [], [{limit,1}]).
... snip ...

2> CL:id().
** exception error: bad argument
 in function  apply/3
    called as apply([{customer,"customer-1","TEST1","First Test Customer",
                               "red",
                               {{2014,8,12},{15,7,21}},
                               ["2014",45,
                                ["0",56],
                                45,"12",32,"15",58,
                                ["0",55],
                                58,"21",46,"486989"]}],
                    id,[])

但是认识到boss_db返回一个列表，并且一切正常：

1> [CL]= boss_db:find(customer, [], [{limit,1}]).
... snip ...
2> CL:id().
"customer-1"

希望这有帮助

芝加哥老板boss_db：找到mongodb

1 个答案: