Question

我已经编写了我的reduce阶段，就像HTML页面的分页一样，后端从0获取请求从而计数为10，这样我就必须在reduce阶段显示返回这些值：

reduce_paginate1(L,Arg) ->
  [lists:sublist(lists:sort(L),Arg)].


reduce_paginate2(L,[Frm,Cnt]) ->
  case Frm > length(L) of
    true -> [];
    false -> [lists:sublist(L,Frm,Cnt)]
  end.

我在我的应用程序中从python-riak客户端调用它：

query.map(['conditions', 'mapfields_check'],
          {
            'arg': [['user_email', 'eq', 'xxxxxxx@gmail.com'],
                    ['template_name', 'assigned_camps']]
          });

query.reduce(['pagiante', 'reduce_paginate1'],
             {'arg':frm + count});

query.reduce(['pagiante', 'reduce_paginate2'],
             {'arg' : [frm + 1,count],"reduce_phase_only1" : True});

抛出错误：

 Error running MapReduce operation. 
 Headers:
     {
        'date': 'Tue, 24 Jun 2014 07:56:38 GMT', 
        'content-length': '1388', 
        'content-type': 'text/html', 
        'http_code': 500, 
        'server': 'MochiWeb/1.1 WebMachine/1.10.0 (never breaks eye contact)'
     }
 Body: 
     '<html>
        <head><title>500 Internal Server Error</title></head>
        <body>
        <h1>Internal Server Error</h1>
        The server encountered an error while processing this request:<br>
        <pre>
          {error,
           {
            exit,
            {json_encode, {bad_term,{reduce,1}}},\n
            [{
              mochijson2,json_encode,2,\n
              [{file,"src/mochijson2.erl"},{line,149}]
             },\n
             {
              mochijson2,\'-json_encode_proplist/2-fun-0-\',3,\n
              [{file,"src/mochijson2.erl"},{line,167}]
             },\n
             {
              lists,foldl,3,[{file,"lists.erl"},{line,1197}]
             },\n
             {
              mochijson2,json_encode_proplist,2,\n
              [{file,"src/mochijson2.erl"},{line,170}]
             },\n
             {
              riak_kv_wm_mapred,send_error,2,\n
              [
               {file,"src/riak_kv_wm_mapred.erl"},\n
               {line,70}
              ]
             },\n
             {
              riak_kv_wm_mapred,pipe_mapred,2,\n
              [
               {file,"src/riak_kv_wm_mapred.erl"},\n
               {line,173}
              ]
             },\n
             {
              webmachine_resource,resource_call,3,\n
              [
               {file,"src/webmachine_resource.erl"},\n
               {line,186}
              ]
             },\n
             {
              webmachine_resource,do,3,\n
              [
               {file,"src/webmachine_resource.erl"},\n
               {line,142}
              ]
             }
            ]
           }
          }
        </pre>
        <P><HR><ADDRESS>mochiweb+webmachine web server</ADDRESS>
        </body>
      </html>'

请建议我如何克服这个问题。

在erlang中运行reduce函数时抛出错误以进行分页

0 个答案: