我怎样才能得到整个结果集之前快递res.render

Question

代码全部工作和页面呈现，但我得到一堆错误 和只有第一行的数据集被写入控制台之前 res.render被称为。

Error: Can't set headers after they are sent.  
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:344:11) 
    at ServerResponse.header  (C:\Node\NodeTestTed\nodetestted\node_modules\express\lib\response.js:718:10) 

    at ServerResponse.contentType (C:\Node\NodeTestTed\nodetestted\node_modules\ 
    express\lib\response.js:551:15) 
    at ServerResponse.send (C:\Node\NodeTestTed\nodetestted\node_modules\express 
    \lib\response.js:138:14) 
    at done (C:\Node\NodeTestTed\nodetestted\node_modules\express\lib\response.j 
    s:957:10) 
     at Object.exports.renderFile (C:\Node\NodeTestTed\nodetestted\node_modules\j 
    ade\lib\index.js:374:12) 
     at View.exports.__express [as engine] (C:\Node\NodeTestTed\nodetestted\node_ 
    modules\jade\lib\index.js:417:11) 
     at View.render (C:\Node\NodeTestTed\nodetestted\node_modules\express\lib\vie 
    w.js:126:8) 
     at tryRender (C:\Node\NodeTestTed\nodetestted\node_modules\express\lib\appli 
    cation.js:639:10) 
     at EventEmitter.render (C:\Node\NodeTestTed\nodetestted\node_modules\express 
    \lib\application.js:591:3) 
    GET /stylesheets/style.css 304 1.596 ms - - 

res.render is called immediatly after the first row is returned from Tedious 

下面是代码：

var express = require('express'); 
var Promise = require('promise'); 

var router = express.Router(); 

/* GET home page. */ 
router.get('/', getClients, function(req, res, next) { 
    console.log("one"); 
    res.render('index', { title: 'Hi There. ' }); 
}); 

router.get('/helloworld', function(req, res) { 
    res.render('helloworld', {title: 'Hello World'}); 

}); 



function getClients(req, res, next) { 
    var promise = new Promise(function(fulfill, reject){ 
    var dataset = []; 

    var Connection = require('tedious').Connection; 
    var Request = require('tedious').Request; 
    var config = { 
     server: '****', 
     userName: '*****', 
     password: '****', 
     options: { 
      instanceName: '****' 
     } 
    }; 

    var connection = new Connection(config); 

    connection.on('connect', function (err) { 
     if (err) { 
      console.log(err); 
      //res.statusCode = 500; 
      // return res.json({ errors:[err] }); 
     } else { 
      // If no error, then good to go... 

      executeStatement(); 
      //console.log("hi"); 
     } 
    }); 

    function executeStatement() { 
    //var promise = new Promise(function(resolve, reject){ 


    var sql = "select people.people_id, evolv_cs.dbo.formatname(people.last_name, people.first_name, people.middle_name) as client " + 
      " from evolv_cs.dbo.people join evolv_cs.dbo.event_log " + 
      "on event_log.people_id = people.people_id " + 
      " and event_log.event_definition_id = 'BA7EF74D-142D-4884-981A-6153755DFBE9' " + // program enrollment 
      " and event_log.program_providing_service = '1D955DBF-529C-42D3-A2DA-C77B2036F642' " + // Central Star PHF - Adolescent 
      " where event_log.end_date is null "; 

    var Request = require('tedious').Request; 
    request = new Request(sql, function (err, rowCount) { 
      if (err) { 
       console.log(err); 
       //callback(err); 
       reject(err); 
      } else { 
      if(rowCount < 1) { 
       callback(null, false); 
      } 
      else { 
       //callback (null, newdata); 
      fulfill(dataset); 
      } 
      } 
    }); 


    request.on('row', function (columns) { 

      columns.forEach(function (column) { 
       console.log(column.value); 

       dataset.push({ 
       col: column.metadata.colName, 
        val: column.value 
       }); 
      }); 
      //newdata.push(dataset); 
      //req.Clients = dataset; 
      //req.body = dataset; 
     // console.log(req.body); 



      next(); 


    }); 


    request.on('doneProc', function (rowCount, more, returnStatus, rows) { 
      //console.log('What TF'); 
      /* arlen = values.length; 
      for (i = 0; i < arlen; i++) { 
       console.log(values[i]); 
      } */ 

      connection.close() 
      console.log('zzz'); 


     //arr = values; 
     // console.log(arr[0]); 

    }); 
    connection.execSql(request); 
    // return resolve(dataset); 
    //}); 
    } 
    }); 
    //console.log(dataset); 

    // end of getclients 

} 



module.exports = router; 

Answer 1

它，因为你在呼唤next()内request.on('row', ...。当你下一次调用时，它会返回控制权来表示调用下一个中间件功能。

您传递给request.on('row', ...的函数将针对查询返回的每一行调用一次。一旦你有了所有的结果，你真的只想打电话给next()。

所以，你需要的next()呼叫转移到这样的事情：

request.on('done', function (rowCount, more, rows) { 
    // process rows 
    next(null, rows); 
});